June science mags

Chemistry

Physical changes

Physical change: a change in matter when a new substance is formed

• The appearance of the substance may change, but no chemical bonds are broken, and no new bonds are formed.

• During a physical change, the properties of the substance do not change

• During a physical change, there is a change in energy

  • Example: heat energy is added to solid water (ice) for it to change to liquid water

• Examples of physical changes:

  • Ripping

  • cutting

  • grinding

  • dissolving

  • changes of state

Chemical changes

Chemical change: a change in matter when substances combine or separate to form new substances

• These substances have different properties as a result of the formation of new chemical bonds and / or the breaking of other chemical bonds.

• During a chemical change, there is a change in energy

• Cannot be reversed

• Evidence that a chemical change has occurred:

  • Colour change

  • Change in heat, light, sound

  • bubbles produced

  • Precipitate (An insoluble solid that emerges from a liquid solution) was produced

• Examples:

  • cooking an egg

  • explosions

  • metal rusting

Chemical and Physical Changes and Energy

Both chemical and physical changes are accompanied by changes in energy

Two types of energy changes:

Exothermic: “exo“ means leaving

• release of energy in the form of heat and / or light

Endothermic: “endo“ means entering

• Energy is absorbed

Chemical reactions

Chemical reaction: a process that involves chemical change

• In a chemical reaction, one or more pure substances are changed into one or more new pure substances (reminder: chemical bonds are broken or formed between atoms)

  • Example: Iron + Oxygen → rust

Chemical equation: uses chemical formula to describe the atoms / molecules that react and those that are produced / formed.

• Example: 2(H2) + O2 →2(H2O)

  • “+“ means “react with“

  • “→“ means “produces“
    

Reactants: atoms / molecules present before the chemical reaction takes place and are on the left side of the arrow in a chemical reaction.

Products: Atoms / molecules present after the chemical reaction takes place and are on the right side of the arrow in the chemical equation

Conservation of Mass and Atoms

Law of Conservation of Mass: “What goes in must come out.“

• The total mass of products equals the total mass of reactants

• The number of atoms of elements that are reactants must equal the number of atoms that are products.

• Atoms of elements are conserved in a chemical reaction.

Writing and balancing chemical equations

Word equation: hydrogen + oxygen → water             (uses words)

Skeleton equation: a chemical formula is correct, but the number of atoms of the elements that are reactants does not equal the number of atoms of the elements that are products.

Ex:        H₂ + O₂ → H₂O

        H = 2                        H = 2

        O = 2                        O = 1

Notice that the number of oxygen atoms is not equal on both sides.

Balanced equation: Shows the number of each atom / molecule in the chemical reaction

How to balance a chemical equation

1. Begin with the skeleton equation.
   

            H₂ + O₂ → H₂O

2. Make a “grocery list“: list the atoms present on the reactants’ side and the products’ sid.e
   

                    H₂ + O₂ → H₂O

            H = 2                        H = 2

            O = 2                        O = 1

3. Count the number of each atom present and write this number beside the symbol.

• Coefficient: A large number in front og the atom or molecule that tells you how many atoms or molecules there are.

• Subscript: A small number to the bottom right of an element symbol that tells you how many atoms of an element there are.

4. Change the coefficients so that the number of atoms on the products side and reactants side equal (note: you can never change the subscript number, only the coefficients)

                                        2H₂ + O₂ → 2H₂O

            H = 2 × 2 = 4                                        H = 2 × 2 = 4

            O = 2                                                     O = 2

Balancing Tips:

• leave the lone elements last

• tackle elements with the largest number of atoms first

• If polyatomic atoms are on both sides, then leave as a unit

• don’t count individual atoms

Electricity

Electrical Energy

Electrical energy: the energy of charged particles

A) Electrical energy has many applications

    What uses electrical energy?

• The human body

  • eg, Moving your eyes to read relies on electrical signals in your muscles

  • eg, Electrical signals help maintain breathing and heartbeat

• Technology

  • eg. touch sensitive screens and robots

B) Many different types of energy can be transformed into electrical energy

• Energy is neither created nor destroyed

• It is transformed from 1 kind of energy to another kind of energy

Types of Energy

1. Mechanical energy: The sum of kinetic energy and potential energy

2. Kinetic energy: Energy of motion.

3. Potential energy: Stored energy that a system has due to its position or condition

            - eg, water at the top of a waterfall, just before it falls, has potential energy because of its               position and kinetic energy because it is moving.

4. Chemical energy: Energy stored in chemical bonds and released when a chemical reaction occurs.

            -eg. Batteries store chemical energy

            -eg. Chemical energy stored in animals and plants is called biomass

            -eg. Fossil fuels (coal, oil, natural gas) store chemical energy.

5. Energy carried by electromagnetic radiation given off by the sun    

            -Fossil fuels and biomass result from energy from the sun being captured by plants and              plant-like organisms.

6. Nuclear energy: Energy generated by forming new atoms

            a) Nuclear fusion: New atoms are made as smaller atoms collide and fuse (occurs in the Sun and                 stars)

            b) Nuclear fission: New atoms are made by splitting larger atoms (carried out in reactors on                   Earth). Most of the energy is thermal, used to boil water into steam. Pressure from the moving                   steam turns turbines connected to generators.

7. Thermal energy: Energy due to the rapid motion of particles that make up an object; detected as heat.

             - Sources include nuclear reactions or from Earth’s interior (geothermal energy), where steam                 and hot water form naturally

             - eg Geysees, volcanoes, hot springs

C) Electrical energy is generated in different ways from different sources.

• Most of the electrical energy in Canada is generated by transforming kinetic energy into electrical energy.

• The source of kinetic energy may be moving water, wind, or moving steam, produced by nuclear reactions or burning fossil fuels.

Kinetic energy to Electrical energy: Generator system

Generator system: A system that transforms kinetic energy into electrical energy

Turbine: Steam, water, or wind causes the turbine to spin

Shaft: As the turbine spins, the shaft spins.

Generator: Kinetic energy is transformed into electrical energy inside the generator

Most of the electrical energy in Canada comes from river flow, fossil fuels, and nuclear reactions.

British Columbia uses river flow and fossil fuels

• River flow is the main source of hydroelectric energy)

  • Water flowing freely in a river turns a turbine

• Thermal energy from burning coal is used to boil water into steam

Other energy sources include:

Wind:

• Kinetic energy of wind is transformed into electrical energy as the moving air turns the turbine of a generator system.

Sunlight:

• Photovoltaic cells transform the energy of visible light into electrical energy.

• When the visible light strikes electrons in the photovoltaic cells, the electrons absorb enough energy to flow freely and generate electrical energy.

Geothermal sources:

• Where the Earth’s crust is thin and molten rock comes through the surface, hot steam can be used to turn turbines to generate electrical energy.

Waves and tides:

• Tides and the rise and fall of waves can turn turbines to generate electrical energy

Static Charge

Static Charge (Static Electricity): an electric charge that stays in one place until it is discharged (lost) to other objects or to the air.

• Measured in coulombs: the unit of electric charge

• It takes the addition or removal of 6.25 × 10 (to the power of 18) electrons to produce 1C of charge.

Positive and Negative Charges in the Atom

• Atoms contain protons (positive) and neutrons (neutral) in their nucleus and electrons (negative) outside the nucleu.s

  • If the number of positive charges equals the number of negative charges, the object is neutr.al

Uncharged Materials:

• Before two materials are rubbed together, they have equal numbers of positively charged protons and negatively charged electrons.

• If the number of positive charges equals the number of negative charges, the object is neutral.

• In a solid material, the positive nucleus stays in the centre of the atom, but the electrons can be rubbed off a material.0

• • All solid materials are charged by the transfer of electron.s

Charged Materials:

• If electrons are rubbed off one material, the protons stay behind, and the material becomes electrically charg.ed

• The material that gains the electrons also becomes electrically charged.

• Electrically charged materials have an unequal number of positive and negative charges.

• When a neutral atom loses electrons (now more protons), it becomes positiv.e

• When a neutral atom gains electrons (now more electrons), it becomes negative

Friction and Electron Transfer

Friction: occurs when objects rub against each other

• Results in one object losing electrons and the other gaining electrons

• Electrons will either stay on the surface of the new material or travel through it

Insulators and Conductors

Insulators: Materials that do not allow electrons to move easily

• Can retain a static charge

  • Examples: glass, plastics, ceramics, and dry wood

Conductors: Materials that allow electrons to flow easily

• Will allow a charge to flow

  • Examples: metals.

Conductivity:

• An indication of how easily charges travel through a material

• Electrons can move through almost all metals (conductors); they can move through some metals more easily than others.

• The higher the conductivity of a material, the more easily electrons can move through it.

Generating Static Charge

Van de Graaf Generator: uses friction to produce a large static charge on a metal dome.

• A moving belt produces a static charge at the base of the generator

• The belt carries the charge to the metal dome, where it is collected.

• Grounding-connecting a conductor so that electrical charge flows into Earth’s surface, makes everything neutral again.

Electrical Force

A force is a push or pull

1. Contact forces: forces that can affect only objects when they touch

2. Action-at-a-distance: forces that can affect an object without touching

• Electric force: push or pull between charged objects

  • An electric force is an example of an action-at-a-distance force

The Laws of Static Charge

1. Like charges repel

   1. Positive - Positive charges repel

   2. Negative - Negative charges repel

2. Opposite charges attract

   1. Positive - Negative attract

3. Neutral objects are attracted to charged objects

   1. Positive - Neutral attract

   2. Negative - Neutral attract

Coulomb’s Law

• If the amount of charge increases, the electric force increases

• If the distance between charged objects increases, the electric force decreases.

Charging by Conduction

Charging by Conduction: objects become charged through contact

• When objects touch, electrons move from one object to the other,

  • ex walking across a carpet and touching a metal doorknob

Charging by Induction

Charging by Induction: when objects are charged without touching or making direct contact

• Electrons do not move from one object to another

• Electrons reposition themselves in the object that becomes charged

• Because no electrons are transferred, the charge is only temporary

  • ex. dust onthe TV screen

  • When the screen is on, it builds up charge and attracts dust particles

The Attraction of Neutral Objects

• Induction explains why neutral objects are attracted to charged objects

  • Neutral objects are attracted to charged objects because the neutral objects are temporarily charged by induction.

• Example: a balloon that is rubbed on by a sweater (charged by conduction) and becomes negatively charged will stick to a neutral wall

  • The balloon’s negative charges repel the wall’s negative charges

  • The wall becomes positively charged by induction

Electrical Potential Energy & Voltage

Electrochemical cells: convert chemical energy into electrical energy

Battery: a single electrochemical cell or a combination of electrochemical cells connected

Terminals: end points of an electrochemical cell/battery where connections are made

• Negative Terminal: end where electrons accumulate

• Positive Terminal: end that as lost electrons

Producing Voltage

The two terminals in an electrochemical cell/battery are called electrodes

• The electrodes are in an electrolyte, which is a substance that conducts electricity

There are two groups of cells:

• Dry cells: electrolyte is a moist paste (used in flashlights and watches)

• Wet cells: electrolyte is a liquid (used in cars and motorcycles)

The amount of voltage that is produced in an electrochemical cell/battery depends on the types of metal (electrodes) and electrolyte used.

• Most electrochemical cells produce 1.5V or 2V

Electric Potential Energy

• Energy is the ability to do work

• Electric energy can do work

  • When unlike charges are moved farther apart, they gain electric potential energy.

• Electric potential energy: the electrical energy stored in an electrochemical cell

• Electric energy that is moving is kinetic energy

Electric Potential Difference

Voltage: the amount of electric potential energy per coulomb of charge

Volt (V): unit of measure of voltage

Voltmeter: measures voltage between two locations of charge separation

The actual electric potential energy is the product of both the voltage and the amount of charge

Energy = Voltage x Charge

Electric Current

Electric current: a complete pathway that allows electrons to flow

Energy around a circuit

In a circuit:

1. Chemical energy in the battery separates positive and negative charges and gives electrons on the negative terminal electric potential energy

2. Electrons move across the wire as they are repelled by the negative terminal and attracted to the positive terminal

3. Potential energy is transformed into other forms of energy when it passes through a load. (ex. in buzzers, it is transformed into sound energy)

Ciruit components

Main components of a circuit:

1. Source: where the electrical energy comes from (electrochemical cell or battery)

2. Conductor: the wire through which electric current flows

3. Load: a device that converts electrical energy into other forms of energy

• examples: light bulbs, heaters, radios

• As electrons pass through a load, they lose energy as electrical energy is converted to another type of energy

• A load resists (hinders) the flow of current

  • Electrons in the current collide with atoms that make up the load, or with each other

  • Collisions interfere with the flow of current

4. Switch: a device that can turn the circuit on or off by closing or opening the circuit

• Controls the flow of current

Circuit diagram: a diagram that uses symbols to represent different components

Electrons are so Pushy

• All electrons have a negative charge

  • This means electrons repel/push each other

• Electrons in every part of a circuit are “pushing“ each other, so when a circuit is closed, the load works immediately

Current Electricity

• When a battery is connected to a complete circuit, it causes electrons to move

• Moving electrical charge from an electric current.

Current Electricity: the continuous flow of charge in a complete circuit.

• Chemical energy from a source (cell or battery) causes charges to move through a conductor (wires), carrying energy to an electrical device (cellphone)

• The moving charges are called an electric current

Current: The measure of Flow

Electric current: the amount of charge passing a point in a conductor every second

Symbol for current: I

• Measured in amperes (A)

  • One coulomb of charge passing a given point per second

Ammeter: a device used to measure the current in a circuit

Modelling the Flow of Current

A) Negative terminal repels the negative charges already in the conductor. A positive terminal attracts the negative charges already in the conductor. Electrons move along the conducting wires; electrons from the electrochemical cell move into the conductor.

B) As the electrons pass through the load, they transfer some of their energy to the load. The electrons then leave the load and return to the electrochemical cell.

C) Electrons enter the electrochemical cell; they combine with positive ions to become neutral. Over time, fewer electrons at the negative terminal and fewer positive ions at the positive terminal. The worker (chemical energy) can carry more electrons up the ladder, keeping the number of separated charges equal.

Safety

• never touch exposed wire

• Keep water away from electricity

• Do not overload outlets

• Use circuit breakers and fuses to stop excessive current by interrupting power flow when current exceeds safe limits

Circuit breakers

• A reusable, resettable switch works mechanically to stop power

Fuses

• consists of a metal filament that melts and breaks the circuit

• requires replacement

Resistance and Ohm’s Law

Resistance and the flow of electrons

Resistance: the property of a material that slows down the flow of electrons and converts electrical energy into other forms of energy.

• measured in Ohms (Ω)

Resistor: an electrical component that has a specific resistance

Factors that affect the amount of resistance in a material

• Length of the material the current passes through (longer = more resistance)

• The cross-sectional area is inversely proportional to the resistance (thinner = more resistance)

• type of material the current passes through (material’s resistivity)

Resistance and Current

Voltage is directly proportional to current:

• If you increase the voltage connected to a circuit, the current will also increase

Resistance and current are inversely proportional:

• If you increase the resistance in a circuit, the current will decrease.

Short Circuit

Short circuit: A circuit with a resistance that is too low, making the current so high that it is dangerous

Example:

• If there weren’t a load (light bulb) to resist the flow of current, the current would be so large that the conductor would get very hot and start a fire.

Ohm’s law

• Electrical Resistance: ratio of the voltage to the current

• Ohms (Ω): unit of measurement for resistance

Ohm’s Law:

Voltage (V) = Current (I) x Resistance (R)

To use Ohm’s law, you need the following units of measurement

1. Voltage: Volts (V)

2. Resistance: Ohms (Ω)

3. Current: amps (A)

Examples:

1. A starter motor of a car is connected to a 12V battery. If the starter motor has 75A of current going through it to start the car, what is the resistance of the starter motor?

    Voltage = Current x Resistance

    Resistance = Voltage ÷ Current

    Resistance = 12/75

                         = 0.16Ω

Converting Prefixes

Milli (m) represents 1/1000

Kilo (k) represents 1000

Mega (M) represents 1 000 000

2. A 92Ω resistor has a current of 78mA flowing through it. What is the voltage in the resistor?

        Voltage = Current x Resistance

        78mA = 78 ÷ 1000 = 0.078A

        0.078A x 92Ω = voltage = 7.176 V

Determining the Resistance

Methods of determining resistance:

1. Experimentally measure the voltage and the current through the load

2. Use an ohmeter to measure resistance directly

Series and Parallel Circuits

Circuits can be connected in two ways

1. Series: a circuit that has only one path for current to travel (ex. Christmas Lights)

2. Parallel: a circuit that has more than one path for current to travel (ex. House Lights)

Charges with one path to follow (Series Circuit)

• Electrons must travel through all components of the circuit

  • If one part of a circuit is not connected (ex. a switch is open), all electrons are blocked and the current stops

Voltage and Current in a Series Circuit

• In an electric circuit, the charge that leaves a battery “loses“ all its voltage before it returns to the battery.

• Each load in a series circuit loses a portion of the total voltage supplied by the battery

• In a series circuit, the total voltage of the circuit equals the sum of the voltages lost on loads

• The current in each part of a series circuit is equal.

In a series circuit:

Current: I₁ = I₂ = I₃ (same throughout)

Voltage: V_total = V₁ + V₂ + V₃

Resistors in Series

• Resistors placed in series increase the total resistance of the circuit

• If you increase the total resistance of the circuit, the total current through the circuit decreases.

More than one way to go (Parallel Circuit)

• a closed pathway that has several different paths for electrons to travel in order to return to the battery

Voltage and Current in a Parallel Circuit

• In an electric circuit, the charge that leaves a battery “loses“ all its voltage before it returns o the battery

• Since all pathways of a parallel circuit connect at the same location, the voltage lost on each of these pathways is identical

• Loads that are parallel have the same voltage

Junction point: where a circuit divides into multiple paths, or where multiple paths join

• No current is created or destroyed; it’s only split into different pathways

• Currently entering much divide amoung the possible paths

• The amount of current through each of these pathways is dependent on the resistance of the path

• The total current entering a junction point must equal the sum of the current leaving the junction point

In a Parallel Circuit

Current:     I_total = I₁ + I₂ + I₃

Voltage:     V₁ = V₂ = V₃

Resistors in parallel

• When you place a resistor in parallel with another resistor, you create another pathway, so the total resistance must decrease (There are more paths for the electrons to flow, so less backup)

• More current will travel through a path of lower resistance than a path of higher resistance

The Power of Electricity

A Matter of Time and Energy

Power: The rate of change in energy

• The rate at which work is done, or energy is transformed

• Watt (W) is the unit for measuring power

A device that can transform one form of energy into another form in a short period of time has more power

Electrical power: The rate at which electrical energy is used by a load

• Load: an appliance (washing machine, TV)

• Phantom Load: Electrical energy a device uses when it is turned off (stand-by mode on TVs)

Calculating Electrical Power

Power (P) = Voltage (V) x Current (I)

To calculate the power in watts, use the following units of measurement

1. Voltage - Volts (V)

2. Current - Amps (A)

Examples:

1. A lightbulb has a current of 0.625 when it’s plugged into a 120V outlet. What is the power of the lightbulb?
   
   0.625A × 120V = 74 Watts
   

2. A PS is rated 380W. When a student plugs the system into a 120V outlet, what is the current in the system?
   380W ÷ 120V = 3.2 Amps

A Larger Unit for Energy

Kilowatt-Hour (kW$\cdot$ h): a larger unit of energy

1.0 Kilowatt-hour = 1.0 kilowatt × 1.0 hour

Power = kilowatt (kW)

1kW = 1000 W

Time = hour (h)

1h = 3600

Paying for Electricity

• Smart meter: An electrical energy meter that measures how energy use changes in a building over the course of the day

• The power company charges a fixed amount of money for every kilowatt-hour of electrical energy used

Example:

If a household uses 12000kW$\cdot$h in a month at a rate of 7.38 cents for every kW$\cdot$h of energy, how much is that month’s electric bill?

12000 × 0.0738 = $885.6

Renewable Energy Sources

• Renewable energy sources: An energy source that is available continuously

  • Ex: Sunlight, wind, river flow, tides and waves, geothermal sources, biomass

• Renewable energy sources provide alternative options for generating electrical energy

  • Examples in BC: Bennett dam, Bear Mountain Wind Park, The Klemtu Small-scale Hydro and Solar Project

• Nonrenewable energy source: An energy source that s non-replaceable in a human lifetime

  • Ex: Coal, natural gas, uranium (nuclear reactions)

Sustainable Energy System: A sustainable way of perceiving, producing, and using energy

• Ensuring that the extraction, production, and use of energy have limited impact on environmental and human health

• Less reliance on nonrenewable sources

• Ensuring the availability of renewable and reliable energy sources for current and future generations

• Providing access to affordable energy for earth’s entire population

First Peoples Ecosystem based Management (EBM)

Respect and Responsibility:

• making decisions that respect the natural world.

• responsible use of resources
  

Inter-generational Knowledge:

• Listening to Elders and sharing knowledge between generations

Balance and Interconnectedness

• balance makes sure future generations are considered

• Interconnectedness takes many relationships with an ecosystem into consideration

Giving and Receiving

• Giving thanks for natural resources recognizes their value

• Benefits of resources are shared in a community

Earth’s Systems

Earth’s 4 Spheres

1. Geosphere (Land)

2. Hydrosphere (Water)

3. Biosphere (Living things)

4. Atmosphere (Air)

The Hydrosphere

• All forms of water in Earth’s environment

  • Includes oceans, all water found on Earth’s surface, snow / ice / glaciers, water found under Earth’s surface, water vapour in the atmosphere

• Water cycles through evaporation, condensation, and precipitation

The Geosphere / Lithosphere

• All of the solid, rocky land on Earth’s Surface (Crust)

• Semi-solid land under the Earth’s surface (Mantle)

• Liquid near the centre of the planet (Core)

• Mountains, valleys, rocks, minerals, soil

• Constantly being shaped by outside forces

  • Sun, wind, ice, water, chemical changes

The Atmosphere

• The gaseous part of the Earth

• The upper portion of the atmosphere protects the organisms of the biosphere from the sun’s ultraviolet radiation

  • Also absorbs and emits heat

Solar energy

• Solar energy that reaches Earth is reflected and absorbed by Earth’s atmosphere / surface

• Solar energy heats Earth’s surface unevenly, and global winds / ocean currents help redistribute thermal energy around Earth

• Solar energy enters the biosphere through photosynthesis and cellular respiration

• The amount of solar energy that reaches different regions of Earth varies, so it heats Earth’s surface unevenly

  • The Earth is spherical

  • Solar energy strikes the Earth at different angles

  • Receives more direct solar energy at lower latitudes (Mexico)

  • Therefore, the atmosphere heats up unevenly

Greenhouse Effect: Solar energy is either:

• Reflected of Atmosphere

• Reflected off the surface of the Earth

• Absorbed by / warms the surface

Global Winds

Earth’s major wind systems redistribute thermal energy around the Earth

• Convention Currents

  • Warm air near Earth’s surface rises and cools

  • Cool air is denser and sinks, creating wind that moves warm and cool air around Earth

Coriolis Effect:

• A change in the direction of moving air, water, or other objects due to Earth’s rotation

• When the air temperature changes, weather occurs

• Ocean currents also move thermal energy around the Earth

  • Surface currents are created

  • 5 major sets of surface currents (1 in each ocean basin)

• Warm currents move warm water to the poles.

• Cold currents bring cold water to tropical regions

Biosphere

• Biotic elements:

  • All microorganisms, plants, and animals on, above, or under the earth. (Found throughout all other spheres)

• All life exists in the Biosphere

• Biodiversity:

  • A large variety of organisms is often an indicator of the health of the ecosystem

• The biosphere cannot survive without elements from all the other spheres

  • Plants and animals need water from the Hydrosphere

  • Minerals from the Lithosphere

  • Gases from the Atmosphere

  • Air, water, and land provide homes for all forms of life

• All living things depend on non-living things for energy, water, and space

  • Living things need nutrients

  • Decomposers recycle nutrients into inorganic material that can form part of the soil

• The environment contains all the factors that surround and influence the biotic and abiotic components within it.

• The environment is our surroundings

  • each living thing within the biosphere habitats nd interacts with the things that surround them

• Ecosystem:

  • A smaller function within the environment

  • The unique interaction between the living and non-living elements

    • A community functioning together as one unit

• Abiotic components of an ecosystem support the life functions of the biotic components of an ecosystem

• Biotic Parts:

  • Living parts of an environment

• Abiotic Parts:

  • Non-living parts of an environment

• Biotic and Abiotic parts of the environment are connected through how they interact with each other

Biotic and Abiotic Interactions

• Organisms within communities constantly interact to obtain resources such as food, water, sunlight, or habitats.

• Every organism has a special role within an ecosystem

• Natural processes move matter in cycles from the biotic and abiotic parts of the environment

• An ecosystem has abiotic components, such as oxygen, water, nutrients, light, and soil, that interact with biotic components, such as plants, animals, and microorganisms

  • Oxygen for cellular respiration

  • Water for survival

  • Nutrients are chemicals that are required for plant and animal growth (Nitrogen / Phosphorus)

  • Light is required for photosynthesis

  • Soil anchors plants and supports many small species of organisms

• Interactions are needed to provide a constant flow of energy to sustain the biosphere

• Food Chain:

  • A model that describes how food energy is passed from one living thing to another

    • Energy flows from producers (Plants) to primary consumers (herbivores) to secondary and tertiary consumers (carnivores)

    • Each step in a food chain is called a trophic level

• Energy Pyramids:

  • Model how energy is lost at each trophic level of a food chain

    • Food energy is lost to obtain / digest food, repair tissues, move, heat, etc.

    • Only 10% of food energy can be passed from consumer to consumer

• Producers:

  • Living things that make their own food to get the energy they need to live (become an energy source)

    • Usually, through photosynthesis by plants and single-celled organisms

• Decomposition:

  • Breaking down of dead organic material

    • By decomposers (ex. Bacteria and fungi)

Food Webs

• Food web: A model of feeding relationships shows a network of interacting and overlapping

  • The change in the number of 1 organism could affect several food chains in the food web

  • All organisms in an ecosystem are connected and depend on each other for survival

Why are there limits to the length of a food chain?

• Most of the energy transferred from one organism to another is lost to the environment as unusable heat

• Some energy has already been used to support life functions (growth, cellular respiration)

• Some energy is stored in wastes that are excreted

• Less and less energy is available to each organism in the food chain

• Consumers:

  • Living things that eat producers or other consumers to get the energy they need

• Herbivores:

  • Primary consumers that eat plants

• Carnivores:

  • Secondary consumers that eat primary consumers

• Omnivores

  • Eats both plants and animals

  • Interconnected food chains form a food web

• Detrivores:

  • Eats the bodies of small dead organisms / plant matter, and animal wastes

Photosynthesis and Cellular Respiration

• Photosynthesis and cellular respiration balance each other out

• Each process makes the raw materials that other processes need to store or release energy

  • Photosynthesis stores energy, while Cellular respiration releases energy

  • Photosynthesis uses carbon dioxide and water and produces glucose and oxygen, while Cellular Respiration uses glucose and oxygen and produces carbon dioxide and water
    

• Photosynthesis: Light energy into chemical energy

• Cellular respiration: Chemical energy is converted into other forms, like kinetic energy and heat.

Hydrosphere

The water cycle

• All water on Earth continuously cycles through ecosystems through the interaction of 3 main processes in the water cycle
  

  • Evaporation:

    • Heat from the sun causes water at Earth’s surface to evaporate

  • Condensation:

    • As warm air rises, it cools and condenses, forming clouds

  • Precipitation:

    • Water falls back to Earth’s surface when it rains or snows

• Water moves over earths surface (“run-off“) and moves downhill back into the ocean water due to gravity

• Water moves through the biosphere by transpiration

• Transpiration: Process by which water is abosrbed by the roots of the plants, carried through the plant, and lost as water vapour through small pores in the leaves

• A small portion of the water in the hydrosphere is fresh

  • ex. Precipitation, rivers, streams, groundwater, frozen glacier

• 97% of Earth’s water is salty (oceans)

• Ocean currents also redistrubute thermal energy and nutrients around earth

• Surface currents are created by wind

Surface Currents

• Warm currents:

  • move heat (warm water from the equator) towards the poles (Higher, colder latitudes)

• Cold Currents:

  • Bring cold water from colder higher latitides to tropic regoins

Great Ocean Conveyer Belt

• Great Ocean Conveyer Belt:

  • A massive system of deep-water currents that move deep water, thermal energy, and nutrients around Earth

• Movement of these currents is based on the differences between the temperature and salt content of water

  • Cold water is more dense than warm water

    • Cold water sinks and displaces the warm water

  • Saltier water is more dense than less salt water

    • Saltier water sinks and displaces less salty water

• It also moves nutrients such as nitrogen and phosphorus around the ocean

  • Surface water that sinks does not have many nutrients

  • After the water sinks, bacteria in deep water break down organic material and returns nutrients to the water

  • When the deep water returns to the surface, it has high concentration of nutrients

Water Pollution

• Water Pollution:

  • Any physical, biological, or chemical change in water quality that harms organisms or that makes water unsuitable for desired uses

• Synthetic (human-made) chemicals and pollutants enter the environment in air, water, or soil

• Decomposers cannot break down through the biodegradation process so they stay in the environment for a long time

• Sources of Pollution Include:

  • Point Sources

  • Non-Point Sources

• Point Sources:

  • Easy to monitor and regulate

    • ex. Factories, power plants, sewage treatment plants, oil wells

• Non-Point Sources:

  • Difficult to monitor, regulate, and treat because the pollution is periodic

    • ex. Run-off from farms / lawns, construction sites, logging areas, roads, and parking lots.

Bioaccumulation

• Bioaccumulation:

  • The gradual build-up of these chemicals / pollutants in cells and tissues

• These chemicals can harm organisms

  • Birth defects and can affect body systems

    • ex. Red Tide (Algae toxins taken in by clams, human shellfish PCBs and orcas, raptors)

Biomagnification VS. Bioremediation

• Biomagnification:

  • The increase in concentration of pollutants in tissues of organisms that are at successively higher levels in a food chain / web

• Bioremediation:

  • A method that uses living organisms to help clean up chemical pollution naturally

    • Some microorganisms naturally feed on chemicals and reduce them to non-toxic compounds

    • Plants can act as stabilizers, reducing wind and water erosion that could spread the containments

Carbon Cycle

Nutrient Cycles

• Nutrients are chemicals required for growth and other life processes

  • carbon, oxygen, hydrogen, nitrogen, and phosphorus

• There are sources, stores, and sinks for each nutrient

• Nutrients flow in and out of stores in nutrient cycles

• Without interference, generally, the amount of nutrients flowing into a store equals the amount of nutrients flowing out (Balanced)

Carbon Stores

• Carbon atoms are a fundamental unit in the cells of all living things

• Carbon can be stored in many different locations

  • Short Term Storage:

    • Aquatic and terrrestrial organisms

    • CO₂ in the atmosphere

    • Top layers of the ocean

  • Long Term Storage

    • Middle and lower ocean layers

    • Coal, oil, and gas deposits in land and ocean sediments (Carbon stored in the decomposing remains of organisms buried deep in the ground transforms into these carbon-rich fossil fuels [Coal, oil, natural gas])

• Caron is cycled through interactions between living and non-living things
  

• The carbon cycle:

  • Carbon dioxide gas moves from the atmosphere into the biosphere through cellular respiration and photosynthesis

  • Carbon Dioxide also moves back into the atmosphere when organisms die and decompose

  • Carbon enters the geosphere when the remains of organisms are trapped under sediment layers

• Human activities can upset the natural balance of nutrient cycles

  • Land clearing, agriculture, urban expansion, mining industry, motorized transportation and burning fossil fuels can all increase he levels of nutrients by reintroducing carbon from stores and from reducing plants that absorb and convert CO₂

Global warming and global climate change

• Carbon Dioxide is a greenhouse gas (Absorbs solar energy in the Earth’s atmosphere)

  • Extra carbon dioxide in the air traps heat in the atmosphere, leading to global warming and global climate change

• Global Warming:

  • An increase in the average temperature of Earth’s Surface

• Global Climate Change:

  • A long-term change in Earth’s climate

    • Causes:

      • Natural:

        • Natural greenhouse gases, changes in ocean and atmospheric circulation, and changes in Earth’s orbit

      • Human Activity:

        • Increase in greenhouse gases due to the burning of fossil fuels.

The effects of excess Carbon in the Carbon Cycle

• Earth’s surface temperature jas increased by between 0.56 °C and 0.92 °C in the past 100 years

• This small change can affect conditions in all of:

• Warmer Temperature:

  • Land and sea ice melt

    • sea level rises  

      • Coastal flooding occurs

  • Warmer seawater absorbs more CO₂

    • Seawater becomes more acidic

      • Coral reefs and other ecosystems are harmed

  • Extreme weather events increase

    • More frequent heat waves

      • Human illness and fatalities occur

• Melting sea and Land ice:

  • Has led to the destruction of habitats for polar organisms, increased local flooding, and the release of methane gas (A greenhouse gas) from melting permafrost.

• Rising Sea Level:

  • Some islands have gone underwater

  • Salt water gets into the drinking water supply

  • Coastal flooding and destruction of wetlands

• Changing Ocean Chemistry:

  • The ocean becomes more acidic because it absorbs more carbon dioxide from the air.

  • An acidic and warming ocean can destroy coral reefs and corals themselves (acidity dissolves the organisms’ shells)

Naturally Occurring Greenhouse Gases

Water Vapour:

• Sources:

  • Evaporation from water

  • Given off by plants, animals, and other organisms

• Other Details:

  • Most abundant greenhouse gas

  • Produced during cellular respiration and certain plant processes

Carbon Dioxide:

• Sources:

  • Living organisms

  • Volcanoes, forest fires, decaying organisms, and the release from oceans

• Other Details:

  • The second most abundant greenhouse gas

  • Produced in and by the cells of most living organisms through cellular respiration

Methane:

• Sources:

  • Certain species of bacteria and other microorganisms that live in and around bogs, wetlands, and melting permafrost

  • Certain species of bacteria that live in the guts of animals, such as cows and termites

  • Vents and other openings in Earth’s crust on the ocean floor

• Other Details:

  • A by-product of cellular processes used by some microorganisms to extract energy from food in the absence of oxygen

Nitrous Oxide:

• Sources:

  • Bacteria that live in oceans and wet, warm soils, such as those in the tropics

• Other Details:

  • Produced when certain species of bacteria break down nitrogen-rich compounds for food

Greenhouse gases can also be released into the atmosphere from human activities

• Carbon Dioxide:

  • Released when fossil fuels (oil, natural gas, coal) are burned

• Nitrous oxide:

  • Enters the atmosphere when fertilizer is applied to crops

• Methane:

  • Released in large amounts by herds of cattle

Nitrogen Cycle

Nitrogen

• Nitrogen is very important in the structure of DNA and proteins

• Nitrogen is stored in oceans, lakes, marshes, and soil

• The largest store of nitrogen is in the atmosphere in the form of N₂ (unusable form)

  • Nitrogen fixation:

    • Processes that make this nitrogen available to plants (Part of the Nitrogen Cycle)

• Nitrogen is cycled through interactions between living and non-living things

Nitrogen Fixation

• Nitrogen is a nutrient that cells need to build proteins

• Nitrogen makes up 78% of air, but organisms cannot use this form of nitrogen

• Nitrogen-fixing bacteria in soil and water change nitrogen into forms that plants can use

• Nitrogen fixation is the conversion of N₂ gas into compounds that are usable by plants

  • Lightning (In the atmosphere) provides the energy for N₂ gas to react with O₂ gas to form nitrogen-containing compounds that enter through rain

Nitrification

• Nitrification occurs when certain nitrifying bacteria convert ammonium (NH4+) into nitrate (NO3-)

• Takes place in 2 stages:

  • Ammonium (NH4+) → Nitrate (NO2-)

  • Nitrite (NO2-) → Nitrate (NO3-)

• Nitrate enters plant roots through the process of uptake

  • Herbivores then eat plants and use nitrogen

Nitrogen Cycling

• Dentrification:

  • Nitrates are converted back to N₂ by denitrifying bacteria (released into the atmosphere)

• Volcanic eruptions

• Nitrogen dissolves in water, enters waterways and is washed into lakes and oceans and settles in sediments

• Nitrogen trapped in rocks

Human Influences

1. Using fertilizer (which contains nitrates) in agricultural practices increases the concentration of nitrogen in the soil

   • Excess nitrogen is washed away or leaches into the waterways

   • This promotes huge growth in aquatic algae called algae blooms

   • Algae blooms use up all the CO₂ and O₂ and block sunlight, killing many aquatic organisms

   • Algae blooms can also produce neurotoxins that poison animals

2. Burning fossil fuels (factories and vehicles) releases nitrogen oxides

3. Clearing the forest by burning releases trapped nitrogen into the atmosphere, which increases acid precipitation

Algae Bloom

• Rain carries nitrogen from farms, gardens and lawns into aquatic ecosystems

• Algae and plants at the water’s surface grow quickly. This blocks sunlight from reaching deeper water

• Deep-water plants get no sunlight and cannot carry out photosynthesis, no longer give off oxygen and soon starve to death

• When the plants die, decomposers have lots of food. The number of decomposers increases quickly. They use up all the oxygen in the water as they carry out cellular respiration

• As oxygen in the water is used up, aquatic organisms that need the oxygen suffocate and die

The Phosphorus Cycle

Phosporus

• Phosphorus is a nutrient essential for the growth and development of organisms

• It is cycled through interactions between living and non-living things

Weathering

• Phosphorus is stored in the geosphere

• Natural weather processes release phosphorus from rocks

  • Chemical weathering, via acid precipitation

  • Physical weather, including wind, water, and freezing

• Phosphorus is then absorbed by soil and plants, which animals then eat

• Decomposers break down animal waste and dead organisms, which then return phosphorus to the soil and water

Human Impacts on Phosphorus

• Fertilizer use

  • Run-off can lead to algae blooms that block the sunlight from reaching organisms in the deep water (organisms die)

• Mining

• Household cleaners and detergents

• All produce excess phosphorus that leaches and runs off into different systems

Nutrient Cycles and Biodiversity

• Any significant changes to any of these nutrients (C, N, or P) can greatly affect biodiversity

• Slight temperature fluctuations caused by global warming and changes in water levels can drastically change ecosystems

• Increased levels of nitrogen can allow certain plant species to outcompete other species, decreasing resources for every species in the food webs

• Earth's spheres are interconnected, so any change in one will greatly impact all the others.

Sustainability

• Sustainability:

  • The ability of an ecosystem to continue to exist indefinitely by recycling its materials

• Sustainability ensures balanced systems now and for the future

• Natural ecosystems are sustainable as long as they have a continuous and constant source of energy

• Ecosystem services:

  • The benefits that organisms receive from the environment and its resources

    • Ex. food production, water supply, raw supply, climate regulations, gas supply, etc.

• We must use these services without reducing the health of the ecosystem (any change to one part will disrupt the entire ecosystem, making it unbalanced)

• Sustainable practices provide economic opportunities while maintaining biodiversity (a variety of organisms) and ecosystem health

  • Sustainable Earth requires that society’s demand on nature is in balance with nature’s ability to meet that demand

How can individuals make a difference?

• Make proper choices as a consumer

• Volunteer, take public transit, recycle, and use solar power

• Vote in favour of parties that promote a healthy Earth

• Employ smart growth:

  • a strategy focused on concentrating growth in the centre of the city, rather than in outlying areas

    • Homes and businesses are intermixed

    • Green spaces are preserved

    • Enhances public transportation
      

• Inquiring individuals can make a difference

• Responsible decision-making and choices can lead to sustainable practices that benefit all life

• Consumers have power:

  • What choices do you make about the products you will and will not buy?

  • What reasons lie behind, motivate your choice?

  • How can you find out more about the manufacturing conditions and materials used to make a product?

• Volunteers inspire through their commitment and example

  • Where do you, or can you, volunteer your time?

  • Who benefits from your willingness to share a part of yourself?

  • How can volunteering locally have global effects
    

• Citizens have a responsibility:

  • In what ways are you a citizen of your community / province / country / planet?

  • What responsibilities do you have as a citizen?

  • How can you educate yourself about candidates before you vote?
    

• Citizen scientists can make important contributions to science

  • How can you find out more information about local projects you could participate in, such as vernal pool, butterfly, or wildflower surveys?

  • What local projects interest you?

  • How can your local data be used nationally or internationally to help scientists learn more about sustainability?
    

• Science-minded advocacy groups can affect, change, and increase sustainability and stewardship

  • How can you find out more about advocacy groups, their motives, backers, and the causes they represent

  • How can the work you do as a member of an advocacy group lead to changes in legislation that help people protect ecosystems and ecosystem services?

Promoting Sustainability

• Dark Sky Preserve:

  • A park dedicated to reducing the effects of artificial lighting on the nighttime environment

  • Helps protect wildlife in the park that rely on darkness to forage for food, mate or migrate

  • McDonald Park in Abbotsford, B.C., is a Dark sky preserve

• Small-scale and community solar projects can help reduce the use of fossil fuels

• Grand Forks Aquatic Centre in Grand Forks, B.C., uses 18 solar panels to heat pool water and hot tubs

• Vancouver has increased the number of protected (separated from traffic) two-way bike lanes in the downtown core

• Bike-sharing programs also promote cycling for residents and tourists

• Waste Reduction Week:

  • Nationwide program in which students are challenged to have a waste-free lunch (reduce, reuse, recycle at school)
    

• The Scia’new First Nation on Beecher Bay in East Sooke, B.C., is building a sustainable housing development

• Development includes ecologically sustainable technologies (a geothermal heating system to provide heat to homes, and trees removed will be used to make fireplace mantels)

Negative Influences

• Land use, resource use, habitat loss, habitat fragmentation, deforestation, soil degradation, agriculture practices, contamination, overexploitation, extinction, etc.

• Better resource management practices are required
  

Examples of the Effects of Land Use on Habitats in British Columbia

• Land Use Effect:

  • The continuing expansion of populations into ecosystems can affect grasslands, forests, wetlands, and farmland. Urbanization causes biodiversity losses, greater reliance on motorized vehicles, and increased energy consumption.

• Sustainable Approach:

  • Some cities are redeveloping industrial areas or buildings. These projects often include a mix of residences, businesses, and some industries. Waste treatment, storm water collection, native plantings, and other green areas to support native species and human activities are often part of the redevelopment plan.

• Land Use Effect:

  • Clear-cutting large areas of forest at once and constructing steep switchback roads to harvest the timber have resulted in erosion and stream habitat destruction.

• Sustainable Approach:

  • Some forestry companies use forest management practices that allow more trees to remain intact and include streambed restoration (left) and less harmful road-building. These practices consider both ecosystem functions and the economic needs of local communities.

• Land Use Effect:

  • Towns, cities, agricultural fields, and cattle ranches have covered most of our grasslands. Livestock grazing, recreational vehicles, and introduced plants have altered this ecosystem.

• Sustainable Approach:

  • Grassland management plans have been developed to protect the health and functions of natural grasslands and provide protective grazing lands. The success of these plans relies on understanding the relationships between soil and vegetation types, plant succession, and weed control.

Bias

• Being scientifically literate involves being able to recognize and evaluate bias in information

• Bias:

  • A judgement that is based on a person’s knowledge, understanding and beliefs