Chemistry-Unit 1

Atom

Smallest piece of an element

Element

Substance made of 1 type of atom. Listed on the Periodic Table

Compound

Substance made of 2 or more elements chemically joined

Pure

Substance made of 1 type of particle

Mixture

Two or more different particles not chemically joined in a space e.g salt water, air

Molecule

Particle made of more than one atom chemically joined. The elements are usually non-metals. There are weak forces of attraction between molecules.

Particles

General name for any small piece of matter. Can be atoms or molecules (or ions).

Periodic Table

List of all known elements with their symbols.

Formula

How chemists show the combination of elements in a particle e.g CuSO4 or Na

NO3

nitrate

SO4

sulfate

What is in an atoms core?

protons, neutrons

proton charge and atomic mass

+,1

neutron charge and atomic mass

no charge,1

electron charge and atomic mass

-,0

What is the electron filling rule?

2,8,8,7

What is an ion?

An ion is formed when an atom gains or loses an electron

An ion is negatively charged if

it gains an element

An ion is positively charged if

it loses an electron

Physical change

Particles are rearranged but no new particles are made e.g melting, dissolving

Chemical Reaction

atoms in particles rearrange to form new particles

Signs of a chemical reaction

Gas produced, colour changing, temperature change, reactants used up, new substance appears

Signs of physical changes

Produced gas (if boiling or evaporating), temporary colour change, temperature change, change of state

Solute

The substance that dissolves

Solvent

The substance the solute dissolves in

Soluble

Something can be dissolved

Insoluble

Cannot be dissolved

Solution

The mixture of the solvent and the solute

Diffusing

The gradient of a substance through air or water from high concentration to low concentration

Solubility

The maximum amount that can be dissolved in a solvent at a particular temperature

t or f, if you dissolve 40cm3 of salt in 50cm3 of water the volume will be 90cm3

true

t or f, if you dissolve 1g of salt in 200g water the mass will be 200g

false

independent variable

what changes

dependent variable

what you measure

control variable

doesn’t change

Signs of evaporation

Happens at any temperature, only on the surface of a liquid, no bubbles, slow process, cools down a liquid

Signs of Boiling

Happens at a specific temperature, can happen throughout the substance, bubbles of gas are seen, quick process, constant temperature

Why does evaporation happen?

Is evaporation faster at higher temperatures?

Yes

t or f evaporation takes place in all of these places: sea, lake, plants, ground

true

In the water system how does water change?

Evaporation and condensation

In the water system where is water stored?

ocean/sea, lake, river, stream, groundwater

In the water system where does water move?

rivers and streams (watershed), surface run off, percolation through soil and rocks, ground water

saturated solution

a solution where no more solute can dissolve