Chemistry Year 8

What is the charge of a proton?

positive

Where are electrons found in an atom?

In shells around the nucleus

Define the term element.

A pure substance made of one type of atom

What is the chemical symbol for carbon?

C

How many atoms are in a molecule of CO₂?

3

What is formed when two or more elements chemically combine?

A compound

Name one difference between a mixture and a compound.

Mixtures are not chemically bonded; compounds are

What is the atomic number of an element?

number of protons

Which subatomic particle has no charge?

neutron

Formula for water

H₂O (Oxygen + Hydrogen + Hydrogen).

What does a chemical symbol represent?

An element

What is the nucleus of an atom?

The central part containing protons and neutrons

Give an example of a compound.

H₂O

What is the mass number of an atom?

protons + neutrons

What is the smallest unit of matter?

Atom

Define mlecule

Two or more atoms bonded together

Which element has the symbol Na?

Sodium

What type of substance is oxygen gas?

Element

What is the charge of a neutron?

No charge

What is the difference between physical and chemical change?

Chemical change forms new substances; physical change does not

What is a reactant?

A starting substance in a chemical reaction

What is a product?

A substance formed in a chemical reaction

Name one sign of a chemical reaction.

Colour change

What does the arrow in a chemical equation mean?

Produces

Write a word equation for rusting

Iron + oxygen → rust

What is a catalyst?

A substance that speeds up a reaction

What gas makes a glowing splint relight?

Oxygen

What gas makes a "pop" sound with a flame?

Hydrogen

What happens to temperature during an exothermic reaction?

it increases

What happens to temperature during an endothermic reaction?

It decreases

Why is photosynthesis a chemical reaction

New substances are formed

Name the reactants in photosynthesis

Carbon dioxide and water

Name the products in photosynthesis?

Glucose and oxygen

What type of reaction forms new compounds?

Synthesis

What type of reaction breaks compounds apart?

Decomposition

What is the basic unit of life?

Cell

name one difference between plant and animal cells

Plant cells have chloroplasts and a cell wall

What organelle controls the cell?

nucleus

What organelle performs photosynthesis?

Chloroplast

What is the function of the cell membrane

Controls what enters and leaves the cell

Define tissue

A group of similar cells working together

Define organ

A structure made of tissues performing a function

What system transports oxygen around the body

circulatory system

What system breaks down food

digestive system

What gas do humans breathe in

Oxygen

What gas do humans breathe out

carbon dioxide

What is the function of the skeleton

Support and protection

What is the function of the muscles

Movement

What is the function of blood

transport substances around the body

What is the function of the brain?

Control the body

What is the function of the lungs?

Gas exchange

What is the function of the heart?

Pump blood

What is the function of the stomach?

Break down food

What is the function of the kidneys?

Remove waste from blood

What is the function of the small intestine?

Absorb nutrients

What is a force

A push or pull

Name one contact force.

Friction

Name one non-contact force.

Gravity

What is friction?

A force that opposes motion

What is gravity?

A force pulling objects toward Earth

What is the unit of force?

Newton (N)

What is speed?

How fast something moves

Write the formula for speed

Speed = distance ÷ time

What is potential energy?

Stored energy

What is kinetic energy?

Energy of movement

Give an example of potential energy.

A stretched rubber band

Give an example of kinetic energy.

A moving car

What is heat conduction?

Heat transfer through solids

What is convection?

Heat transfer through liquids or gases

What is radiation?

Heat transfer through waves

Why are metals good conductors?

They have free-moving electrons

What happens to particles when heated?

They move faster and spread apart

What happens to particles when cooled?

They move slower and come closer

What is the difference between mass and weight?

Mass is amount of matter; weight is force of gravity

What is the purpose of insulation?

Reduce heat transfer

What is the crust?

Earth's outer layer

What is the mantle?

The layer beneath the crust

What is the core?

Earth's centre

What causes seasons?

Tilt of Earth's axis

What causes day and night?

Earth's rotation

What is a mineral?

A natural solid substance

What is a rock?

A mixture of minerals

Name the three types of rocks.

Igneous, sedimentary, metamorphic

How are igneous rocks formed?

From cooled magma or lava

How are sedimentary rocks formed?

From layers of sediments

How are metamorphic rocks formed?

By heat and pressure

What is erosion?

Movement of sediments

What is weathering?

Breaking down of rocks

What is the water cycle?

Movement of water through evaporation, condensation, precipitation

What is evaporation?

Liquid turning into gas

What is a variable?

Something that can change