Elements, Compounds &; Mixtures, Chemical &; Physical Changes, Energy

______________________________________________________________________________

Meanings:

Element: A substance that cannot be broken down into simpler substances by chemical means.

Compound: A substance made up of two or more different chemical elements combined into a fixed ratio.

Mixture: A substance made by mixing other substances.

Physical Change:

• A change in which no new substance is formed

• Can be a change in shape, expansion & contraction, change of state, and mixing

• Forced applied to break, bend, stretch, crush, twist, or compress an object

Chemical Change:

• A new substance is formed

• We can determine if a chemical change has occurred by:

•  A permanent colour change

• A gas (Bubbles) is given off

• A change in temperature

• The process of rearranging atoms to form new substances is known as a chemical reaction. (MEANING OF CHEMICAL CHANGE)

Changing Of States:

• If enough heat is applied to a substance then the expansion will take place but also the substance will change states.

• A solid can change to a liquid – melting – or from a liquid to a gas – evaporation.

• If enough cooling is applied to a substance then contraction will take place but also the substance will change states.

• A gas can change to a liquid – condensation – or from a liquid to a solid freezing/solidification.

• Some substances can change directly from solid to gas - sublimation – or from a gas to a solid – deposition.

What is Energy/Energy Types:

• Energy is the force that causes things to move

• Energy exist in everything (It CANNOT be destroyed)

• Energy cannot be seen or weighed, but it can be measured (Joules)

• The type of forms of energy include:

• Kinetic Energy: The energy of movement – anything that moves has kinetic energy. The faster the object the higher the amount of kinetic energy.

• Heat Energy: From the sun, fire, chemical reactions, electrical devices, and even from body heat (human/animal). Heat can warm, dry, melt, and make hot air balloons rise (When you yawn heat energy is produced)

• Light Energy: From sun, light globes, fires, animals (glow worms)

• Sound Energy: Vibrations from moving air. Sound from voice, instruments, cars, and power tools

• Electricity Energy: From power stations, solar cells, batteries, and lightning. Electrical energy powers all electrical devices such as TVs, laptops, mobile phones, and cooking devices.

Energy Calculation:

1 KJ = 1000 J

1MJ = 100000 J

Stored Energy = Potential Energy

Types Of Potential Energy:

• Many objects have stored energy (AKA- Potential Energy)

• Types of potential energy include:

• Gravitational Potential Energy: Stored in an object when it is above the ground. The higher the object the greater the Gravitational Potential Energy.

• Chemical Energy: Energy stored in substances such as food.

• Elastic Potential Energy: Energy stored in a stretched or squashed spring. Can also be found in elastic bands (elastic potential energy). This energy gets released when the elastic band is let go.

• Nuclear Energy: Stored inside atoms that make up all matter. Nuclear energy is released in nuclear power plants or when bombs explode and inside the sun.

Types Of Energy Transfer:

• Heat Transfer – Heat energy from a heater can be transferred from the heater to you. If you stand in front of a fire, you will warm up and start to get hot. Heat energy can be transferred in three ways.

• Conduction – Occurs between two objects that come into contact with each other. Heat transfers from the hotter object to the cooler one. This occurs until they are at the same temperature.

• Convection – Heat travels through liquids and gases – Heat rises, making it hotter near the ceiling, compared to the floor. Convection spreads heat from ducted heating vents (air con) through the rooms of the house.

• Radiation – Heat radiates (spreads outwards) from a hot object. Radiant heat is transferred as a wave that travels through air and space.

Electric Charge:

Atoms are the tiny building blocks that make up everything around us. They are made of three parts:

• Protons: Positive (+) particles in the middle (nucleus) of the atom.

• Neutrons: Neutral (no charge) particles also in the nucleus.

• Electrons: Negative (-) particles that move around the outside of the atom.

How Do Ions Form?

• Atoms can gain or lose electrons.

• Losing electrons makes the atom positively charged, forming a positive ion – Known as a Cation.

• Gaining electrons makes the atom negatively charged, forming a negative ion – Known as an Anion.

• Neutral vs. Charged Atoms: A neutral atom has the same number of protons and electrons.

• Ions have different numbers of protons and electrons, which gives them a charge.

Principle Of Conservation Of Energy:

Energy can neither be created nor destroyed, it only changes forms (e.g. kinetic and potential energy). EXAMPLE = When you turn on a light switch for a light bulb it goes from electrical energy to light energy, and thermal energy.

Current Electricity:

• Current electricity is when electric charges (electrons) flow through a wire.

• The electrons move from a place with more charge to a place with less charge.

• When the electrons flow through different devices, they can:

• Make light bulbs glow.

• Turn motors.

• Produce heat in devices like toasters.

Simple Electrical Circuits:

• An electric circuit is a pathway that lets electricity flow.

• Parts of a Simple Circuit:

• Energy Source: This is like a battery, which pushes the electrons around.

• Energy User: This could be a light bulb or a motor, which uses electricity.

• Wires: These connect everything and let the electricity flow.

Open vs. Closed Circuits:

• Closed Circuit: The electricity can flow all the way around.

• Open Circuit: There is a break, so the electricity flow stops.

Periodic Table: (Learn the first 20 Elements)

First 20 Elements and their properties:

Hydrogen: colourless, odourless, tasteless, flammable.

Helium: colourless, odourless.

Lithium: soft, silvery metal.

Beryllium: silvery-white, lustrous, soft metal.

Boron: light, flammable, tough.

Carbon: both hard and soft

Nitrogen: colourless, odourless, tasteless.

Oxygen: colourless, odourless, higher density than air

Fluorine: pale yellow, diatomic, flammable

Neon: colourless, tasteless, odourless

Sodium: soft metal, malleable

Magnesium: light, silvery-white and fairly tough metal

Aluminum: silvery-white metal, light, low density

Silicon: very brittle, metallic luster (metal like appearance)

Phosphorus: waxy white solid, when pure is colourless and transparent

Sulfur: tasteless, odourless, brittle, pale yellow

Chlorine: greenish yellow, moderately soluble

Argon: colourless, odourless, nonflammable

Potassium: soft and white with a silvery lustre

Calcium: i wanna die rn omdsilvery-white metallic, ductile and malleable.

Lattice Structures:

• There are 7 different lattice structures

• Lattice structures are three-dimensional arrangements of ions or atoms in many different materials and solids.

• Lattices structures are composed of one or more repeating unit cells

Particle Models:

Solids: The atoms of a solid are firmly packed together and vibrate.

Liquids:The atoms of a liquid are more freely distributed compared to solids.

Gases:The atoms of a gasses are extremely free and do not touch.

Energy Efficiency:

Energy efficiency is the use of less energy to perform the same tasks. For example, heating a room with the windows open uses a lot of energy because the warm air escapes through the windows. A way you can save energy is by:

• Solar panels

• Energy saving light bulbs

• Installing a heat pump

• Etc

Properties of:

Elements, Compounds & Mixtures:

• Element: A pure substance that cannot be broken down into simpler substances.

• Compound: A substance formed from two or more elements combined in a fixed ratio.

• Mixture: A combination of two or more substances where each retains its properties.

Changes:

• Physical Change: A change where no new substance is formed (e.g., melting, dissolving).

• Chemical Change: A transformation that produces one or more new substances (e.g., rusting, combustion).

Energy Types:

• Kinetic Energy: Energy of moving objects.

• Potential Energy: Stored energy based on position (e.g., gravitational, chemical, elastic).

• Heat, Light, Sound, and Electric Energy are forms of energy with various sources and applications.

Electricity:

• Current Electricity: Flow of electric charges through conductors.

• Simple Circuits: Composed of an energy source (e.g., battery), energy user (e.g., light bulb), and wires.

Periodic Table:

• Learn the first 20 elements, including their properties to understand basic chemistry.