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Physical Change
Physical changes do not form new substances . e.g. state change
Chemical Change
Chemical changes form new substances.
Signs of a Chemical Reaction
Precipitate Gas formed Color change Smell Energy emitted (endothermic, exothermic) Light, sound emitted
Reactants
The starting substances in a chemical reaction
Products
The substances formed after a chemical reaction
The arrow inbetween a chemical reaction
Means “reacts to form”
Subscripts
Subscripts indicate the number of atoms in each substance.
Coefficients
Coefficients are used to balance the equation.
What happens in a chemical reaction?
In every chemical reaction, the atoms get rearranged and we form new substances with unique properties. Breaking bonds is endothermic
Endothermic
An endothermic change transfers energy from the surroundings. It will cause the surrounding temperature to decrease.
Exothermic
An exothermic change transfers energy to the surroundings. It will cause the surrounding temperature to increase. Forming bonds is exothermic
Law of Conservation of Mass
The law of conservation of mass states that in a chemical reaction, the total mass of reactants is equal to the total mass of the products. Mass is also conserved in physical changes. The law of conservation of mass states that no atoms are lost or made during a chemical reaction so the mass of the product equals the mass of the reactants. Chemical equations are balanced in terms of the numbers of atoms of each element on both sides of the equation.
A balanced chemical equation shows:
The formula of the reactant and product. How the atoms are rearranged. The relative amounts of reactants and products.
Steps to write a balanced equation:
Write the chemical symbol or formula for each reactant and product. Reactants go to the left of the arrow and products to the right. The arrow must point from the reactants to the products. Balance the equation. There must be the same number of atoms of each element on each side of the equation.
IMPORTANT THINGS TO REMEMBER WHEN WRITING BALANCED EQUATIONS…
Diatomic elements are written as molecules: I2, Br2, Cl2, F2, O2, N2, H2, P4, S8 When these form ions, they no longer exist as molecules! They form anions and combine with a cation to form an ionic compound. We observe the law of conservation of mass by balancing equations using coefficients not by changing subscripts. The state of all substances must be listed. Ionic compounds are solids at room temperature. If the reaction is occurring in water/solution, then an ionic compound will be aqueous (aq) or solid (s) - check your solubility table! The state of a pure element is indicated by the colour on your periodic table. In combustion reactions, CO2 and H2O are both formed as gases.
Five Types of Reactions
Formation (Synthesis) Decomposition Single Replacement Double Replacement Hydrocarbon Combustion
Formation (Synthesis) Reaction
In a formation or synthesis reaction, two or more simple substances combine to form a more complex product. The reactants may be elements or compounds, while the product is always a compound. General formula: element + element → compound A + B → AB
Decomposition
In a decomposition reaction, there is one reactant, but two (or more) products. The starting compound is the reactant. It breaks down into simpler substances, which could be elements or simple compounds. General Formula: compound → element + element (or compounds) AB → A + B
Single replacement
In a single replacement reaction (also called single displacement) one element is substituted for another element in a compound. The starting materials are always a pure element and a compound (usually aq!). A new compound and a different pure element will be formed as products. General Formula: element + compound → new compound + different element AB + C → AC + B
Double Replacement
In double replacement reactions (also called double displacement), parts of two ionic compounds are exchanged, making two new compounds. General Formula: AB + CD → AD + CB* *A and C are cations, B and D are anions
Hydrocarbon Combustion
Hydrocarbons are molecules made of hydrogen and carbon. They are the main component of fossil fuels. In a hydrocarbon combustion reaction, a hydrocarbon reacts with oxygen to form carbon dioxide and water vapour. General Formula: hydrocarbon + oxygen → carbon dioxide + water CxHy + O2(g) → CO2(g) + H2O(g)
The Greenhouse Effect
The natural greenhouse effect is the absorption of thermal energy by the atmosphere. Without the natural greenhouse effect, the average temperature on Earth would be about 33°C lower. Greenhouse gases are gases that contribute to the greenhouse effect are water vapour, CO2, CH4, N2O
The Enhanced Greenhouse Effect
The enhanced greenhouse effect is caused by human activities that increase concentrations of greenhouse gases (e.g. CO2 & CH4) in the atmosphere. This causes more heat to be trapped, leading to climate change.
What are chemical amounts measured in?
Moles
The symbol for moles is _
n
The unit for moles is ___
mol
Avogadro’s number/constant
The number of atoms, molecules or ions in a mole of a given substance
What is Avogadro’s number?
6.02 x 10²³ per mole.
Molar Mass
The mass of one mole of something
Atomic Molar Mass for elements
The average mass (in grams) of one mole of atoms of that element.
Units of molar mass
g/mol
The number of moles of a substance is related to its molar mass by the equation:
amount(n) = mass(m) / molar mass(M)
(True of False): Every substance has a unique specific heat capacity
True
Specific heat capacity
This is the amount of energy (in J) required to raise the temperature of 1 kg of the substance by 1°C (Units are J/g °C).
When thermal energy is absorbed by a substance, the temperature increase depends on:
The mass of the substance heated The type of material The amount of energy put in to the system
If a substance has a low specific heat capacity, it heats up and cools down ________
Quickly (It takes less energy to change its temperature)
If a substance has a high specific heat capacity, it heats up and cools down _____
Slowly (It takes more energy to change its temperature)
Water has a very ___ specific heat capacity
high
How does the specific heat capacity of water impact climates across the world?
Regions with little water tend to heat and cool more rapidly than regions at similar latitudes with a lot of water. E.g. Calgary has a more variable air temperature than Vancouver.
Q
The amount of thermal (heat) energy absorbed or released when the temperature of a mass of a substance changes quantity of thermal energy in J
A device used to determine the transfer of thermal energy.
Calorimeter
(True of False): Energy is required to change the state of a substance
True
Melting/fusion
Solid to liquid (Reverse process is freezing: liquid to solid)
Vapourisation/boiling
Liquid to gas (Reverse process is condensation: gas to liquid)
Sublimation
Solid to gas
Deposition
Gas to solid
Heat of fusion (Hfus)
The amount of energy required to change 1 mole of a substance from solid to liquid without a temperature change. The reverse is known as heat of solidification Hfus = Q/n
Heat of vaporization (Hvap )
The amount of energy required to change 1 mole of a substance from liquid to gas without a temperature change. The reverse is known as heat of condensation Hvap = Q/n
Conduction
Transfer of thermal energy through direct contact between the particles of a substance Usually occurs in solids
Convection
Transfer of thermal energy through the movement of particles flowing from one place to another forming a current Usually occurs in liquids and gases
Radiation
Emission of energy through particles or waves. Any substance at a higher temperature than its surroundings will emit radiant energy Can occur in a vacuum
How is thermal energy transferred in the atmosphere?
Thermal energy moves from an area of high temperature to an area of low temperature. Occurs either by convection or conduction
How is energy transferred in the biosphere?
Almost all of the energy on Earth comes from the Sun (solar energy) Solar energy is radiant energy transmitted as electromagnetic radiation (EMR) waves at different wavelengths. thermal energy – infrared waves visible light – as detected by eyes UV light – ultra violet waves Wavelength is a property of the wave that is useful for determining the quantity of energy a wave transfers
Insolation
Insolation refers to the quantity of solar energy received by a area of land
Factors that affect insolation
Angle of Inclination Angle of Incidence Cloud cover & Atmospheric Dust Albedo
Angle of inclination
Angle of inclination refers to the degree that the Earth’s poles are tilted against the Earth’s orbit. Earth has an angle of inclination of 23.5°
What does the angle of inclination affect?
The angle of inclination causes variation in the seasons and the number of hours of daylight at different latitudes. At more northern latitudes, there are more hours of daylight as the North Pole becomes tilted toward the Sun.
Latitude
Latitude refers to the imaginary lines that run parallel to the equator which is at latitude 0°.
Solstice
A solstice is one of the two points in Earth’s orbit at which the poles are the most tilted toward or away from the Sun.
Equinox
An equinox is one of 2 points in Earth’s orbit when the number of daylight hours is equal to the number of hours at night.
How much variance in daylight do regions at the equator face?
Very small variations in daylight.
Angle of incidence
Angle of incidence is the angle between a ray falling from the surface and the line that is perpendicular to that surface.
As you get closer to the poles, the angle of incidence ______
Increases
What happens when radiation hit the earth at larger angles of incidence?
The same amount of radiation is spread over a larger surface area
What is the difference in latitudes closer to the poles versus latitudes closer to the equator in terms of solar energy per square kilometer
Latitudes closer to the poles receive less solar energy per square kilometer than latitudes closer to the equator. This is why the equators are intrinsically hotter than the poles
What is found in the troposphere that impacts the albedo effect?
Clouds and atmospheric dust (and aerosols)
What do clouds and atmospheric dust do to solar radiation?
Clouds and atmospheric dust reflect some solar radiation. They also absorb energy emitted from the surface of the Earth which helps to warm the planet.
Aerosols (not in curriculum)
Aerosols are small particles that are suspended in the air They stimulate cloud growth however the clouds that form on them have smaller droplets This makes the clouds rain less This also helps reflect more sunlight so this gives aerosols a cooling property
Albedo
The albedo of a surface is the percent of solar radiation that it reflects. Light coloured, shiny surfaces such as snow, reflect more solar energy than darker, duller surfaces such as forests. The average albedo for Earth’s surface is 30% but it varies with surface features, seasons, cloud cover and atmospheric dust.
Atmospheric pressure
Atmospheric pressure is the pressure exerted by the mass of air above any point on Earth’s surface Warm air is less dense and exerts less pressure than cool air.
Wind
Wind is the movement of cool air from areas of high pressure to areas of low pressure.
The Coriolis Effect
The Coriolis effect is the deflection of any object from a straight line path by the rotation of Earth. This causes the moving wind to turn: Right in the Northern Hemisphere Left in the Southern Hemisphere
What do convection currents in the atmosphere and the Coriolis Effect do to thermal energy transfer?
The convection currents in the atmosphere along with the Coriolis effect result in global wind patterns that transfer thermal energy from areas of net radiation budget surplus to areas of net radiation budget deficit.
Jet Streams
A jet stream is a band of fast moving air in the stratosphere Because of the high altitude they are not subject to friction resulting from the Earth’s surface and the density of the troposphere. Speed and temperature vary with the amount of thermal energy in the atmosphere. Changes in the jet streams affect the formation of severe weather events.
What do global winds do?
The hydrosphere transfers thermal energy from the warmer latitudes near the equator to cooler areas near the poles through global winds.
How are ocean currents modified by the Coriolis Effect?
Ocean currents are modified by the Coriolis Effect so that in the Northern Hemisphere, currents are driven clockwise; Southern Hemisphere is counterclockwise
How is thermal energy transferred vertically?
Through convection currents Example: The density of water decreases when its temperature increases, so warm water tends to rise. Warmer water particles move faster so they are spread apart more and become more dense because of that Cooler water is more dense so it tends to sink. Water has a high specific heat capacity and sand/ soil has a lower specific heat capacity
Scalar Quantity
A scalar quantity can be described by a single number or magnitude only. Eg. A car travels 25 km Some scalar quantities: Speed, mass, time, temperature, energy, distance
Vector Quantity
A vector quantity deals inherently with both magnitude (a number with units) and direction. Eg. A car travels 25 km [East] Some vector quantities: acceleration, velocity, weight, force, friction, displacement
Unicellular
Organism with only one cell
Multicellular
Organism with multiple cells
Properties of unicellular organisms
Limited by surface area to volume ratio One cell has to perform all the physiological needs Short lifespan
Properties of multicellular organisms
Increased surface area overall Specialized cells for each function Longer lifespan
Levels of organization in an organism
Cell→Tissue→Organ→Organ system→Organism All cells in an organism have the same DNA, but each cell turns on specific genes to preform a special function
Cell
The smallest unit of life that is responsible for all of life’s processes
Tissue
Groups of similar cells that perform a specific function
Organ
Group of tissues that work together to perform a specific function
Organ System
A set of organs or parts that performs one or more functions as a unit
The Two Plant Organ Systems
Shoot system Root system
Shoot System
all parts above ground tubers (swollen stem that stores food – below ground) The shoot system consists of stems and leaves, in which photosynthesis takes place
Root System
All roots underground Aerial roots above ground The root system anchors the plant and provides water and nutrients for the shoot system
Types of Plant Tissue
Dermal protection Ground photosynthesis & storage Vascular transport Meristematic cell division (mitosis)
Dermal Tissue (Epidermis) ~ Skin
Location: outer layer of cells Function: Protection Exchange of matter and gases into and out of plant Leaves & Stem → produces a waxy cuticle to limit water loss Root → has microscopic root hairs dermal cells to increase water and mineral salt absorption from soil (osmosis)
Ground Tissue
Location: layer beneath the epidermis makes up majority of plant Function: Leaves → where photosynthesis happens Palisade tissue – tightly packed Spongy mesophyll tissue – loosely packed Stem → strength & support Roots → food and water storage
Vascular Tissue
Location: Center of the plants (looks like long tubes/straws) Function Transports water and minerals up from roots Transports sugars and other nutrients down from the leaves (and up from the roots) Xylem Tissue: transport water and minerals thick walls dead at maturity Phloem Tissue: transport sugars, nutrients living at maturity → both cell types are stacked to form long tubes
Xylem Tissue
Xylem → Water (& mineral) Transport Xi High cylindrical, elongated cells thick walls filled with cellulose and lignin as cells mature, they fuse together and the walls at each end become perforated the contents of the cytoplasm breaks down and cell dies dead at maturity overlap one another at the ends to form continuous tubes from root to shoot (like a long straw)
Phloem Tissue
Sugar transport Phlo Low Sieve Tube Elements: a phloem cell with pores in its side cell walls and a sieve plate at the end walls; sieve tube elements remain alive BUT lack organelles and depend on associated companion cells Companion Cells = small, nucleated phloem cell that is always associated with a sieve tube element
Meristematic Tissue
Meristem = tissue consisting of dividing (via mitosis) undifferentiated cells found in areas of the plant where growth can take place Differentiation = a change in the form of a cell, tissue or organ to allow it to carry out a particular function Apical meristem = a meristem located at any growing tip of shoots or roots, which contribute to increase in the length of plant tissue
Internal Leaf Structure: Mesophyll
The photosynthetic middle layer of cells in the leaf Cells that contain the chloroplasts
Internal Leaf Structure: Palisade Mesophyll
Layer of elongated photosynthetic cells arranged in columns under the upper surface of a leaf Maximum sunlight absorption
Note 
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