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What is the particle model
It explains how particles are arranged and how they move in solids, liquids and gases
What is the different arrangements, distance and movement of particles in each state
Solid - regular, very close and vibrate around fixed positions Liquid - random, close and move around each other Gas - random, far apart and move quickly in all directions
How does this explain properties of substances
You can’t compress a solid or liquid as there is no space for particles to move into. However you can compress a gas. A particle in it’s solid state can’t flow and has a fixed shape as its particles vibrate around fixed positions and can’t move from place to place.
What is a physical change
When a substance changed state or shape
Characteristics of a physical change
No new substances are made Reversible
What is a chemical change
A change that produces one or more new substances
Characteristics of a chemical change
The properties of the new substance formed is different from the properties of the original substances new substance is formed
What happens when a substance changes state
It’s particles stay the same but their arrangement and movement change
What happens in a chemical change
The particles break up and join in different ways
What is an atom and what is a molecule
Smallest particle of an element that still has it’s chemical properties Molecule - two or more atoms joined together by chemical bonds
Where are the subatomic particles found
Electrons - in shells around the nucleus Protons and neutrons - in the nucleus
What is the diameter and radius of the atom
62 x 10 to the -12 metres - diameter 31 x 10 to the -12 metres - radius
What do particle models no take into account/show
The size of the particles The forces between particles The space between particles
Relative mass and charge of the subatomic particles
1, +1 - proton 1, 0 - neutron 0.0005, -1 - electron
What is an isotope
An atom with the same number of protons and electrons but with a different number of neutrons
What does the mass number equal
mass number = number of protons + number of neutrons
What is the atomic number
The number of protons / electrons
What are ions
Ions are charged particles that form when atoms lose or gain electrons
What did John Dalton think about matter
He thought that all matter is made from atoms. He thought of atoms as solid balls and all atoms of the same element were identical and therefore different elements have different atoms
What did J.J Thompson discover
He discovered the electron. By finding out that a cathode ray changed direction in an electrical or magnetic field and that they were negatively charged particles.
Plum pudding model
Made by J.J Thompson they have negatively charged electrons embedded in a positive mass - maintains the neutral charge of the atom.
What did Rutherford and Geiger and Marsden discover
They discovered that there was a positively charged mass in the centre of the atom by shooting positively charged particles at the atom, they expected them to go through the foil but some changed direction and a few came straight back. they concluded there was a positively charged mass in the centre of the atom and the electrons orbited it.
What did Niels Bohr discover
He used mathematical models and found out that the electrons are in fixed energy shells around the nucleus.