Atoms revison

What is an atom

An atom is the smallest particle of a chemical element that can exist

Element

An element is a substance that contains only one type of atom

Compound

A compound is made of two or more types of atom chemically bonded together

Molecule

A molecule is made of two or more atoms bonded together

Pure substance

A pure substance consists of one element or compound

Mixture

A mixture is two or more pure substances together but not chemically bonded

Periodic table

A list of 118 chemical elements listed in order of atomic number

Property

A property is a characteristic of a particular substance

Physical property

A physical property is a characteristic or feature that can be observed or measured without changing the composition

Chemical property

A chemical property is a characteristic or feature that is observed during a chemical reaction

Chemical formula

The ratio of the atoms of elements in a compound

Melting or freezing points

The temperature at which a substance changes state between solid and liquid

Condensation or boiling point

The temperature at which a substance changes state between a liquid and a gas

Diffusion

Diffusion is the net movement of particles from a region of high concentration to low concentration

Pressure

Pressure is the force applied perpendicular to the surface of an object

What is an atom made of

protons, neutrons, electrons

out of protons, neutrons, and electrons, which has the smallest mass?

Electron

Which has a positive charge; neutron electron proton

Proton

Which has a negative charge; proton neutron or electron

Electron

Out of the three sub atomic particles which is on the outer shell

Electron

Out of the three sub atomic particles which two make up the nucleus

Proton and neutron

Atoms of a single element are…?

Identical

What describes an atom

Atomic number e.g. 23 and mass number e.g. 11 for sodium

What does a nuclear symbol tell you

atomic (proton) number and mass number

Which is always higher the atomic number or mass number

The mass number because atomic is the number of protons mass is the number of protons and neutrons

Number of protons

atomic number

Number of electrons

atomic number(atom)

Number of neutrons

The mass number

What are the three states

solid, liquid, gas

The change from solid to liquid is

Melting

The change from liquid to solid is

Freezing

The change from liquid to gas is

Evaporation

The change from gas to liquid is

condensation

The change from gas to solid is

deposition

The change from solid to gas is

sublimation

How do particles change substance with changing state

Increasing temperatures, increasing energy of particles, decreasing attraction between particles, decreasing density

What shows how a substance is cooled

A cooling graph

Why are there flat bits in cooling graphs

It is when the gas/liquid is condensing/freezing

Why does condensing and freezing affect cooling graphs

This is because the forces between particles get stronger when a gas condenses and a liquid freezes and energy is given out this means the temperature doesn't go down until the substance has changed state

What is an example of diffusion

When you spray perfume at the back of a classroom the kids sitting at the back will smell it first because it is an area of high concentration and the kids at the front will smell it last because it an area of low concentration

What is pressure changed by

The temperature and size of the container

How does temperature affect pressure

At a high temperature air particles move around faster so collide with the container more and create a higher air pressure

How does the size of the container affect pressure

Making the volume of the container smaller increases the chance that air particles collide with the container this increases air pressure