Chemistry October Assessment Revision
Particle theory and states of matter
The particle theory is where we use tiny circles to indicate molecules in different states of
matter.
In a solid, the particles have strong bonds and a regular shape. Particles in the solid only vibrate,
they cannot move.
In a liquid, the particles have weak bonds and a quite random structure. Particles in the liquid
can move slowly and have to be connected to at least one other particle.
In a gas, particles can move around freely and don’t take any shape. Particles in a gas can move
around randomly and very fast.
Atoms, elements and compounds
Atom: the smallest unit in existence
Elements: Elements are only made out of 1 singular type of atom
Compound: Where two more different elements are chemically bonded together
Mixture: Where two or more different substances aren't chemically bonded
Molecules: Where two or more atoms are chemically bonded.
Chemical Formulae
Chemical formulae are the way you present out a substance using the Periodic Table.
An example of this is a substance with two hydrogen atoms and one oxygen atom.
First of all, we need to correlate the names of the elements to its chemical symbol: Hydrogen ->
H, Oxygen ->O
Second of all you need to find out how many atoms of each are needed e.g. hydrogen has 2
atoms, oxygen has 1 atom
If we have two hydrogen atoms, we take the chemical symbol then write a 2 next to it e.g. H2.
And then we add a O at the end to represent the 1 oxygen atom
So, two hydrogen atoms and one oxygen atom are H 2O.
Particle theory and states of matter
The particle theory is where we use tiny circles to indicate molecules in different states of
matter.
In a solid, the particles have strong bonds and a regular shape. Particles in the solid only vibrate,
they cannot move.
In a liquid, the particles have weak bonds and a quite random structure. Particles in the liquid
can move slowly and have to be connected to at least one other particle.
In a gas, particles can move around freely and don’t take any shape. Particles in a gas can move
around randomly and very fast.
Atoms, elements and compounds
Atom: the smallest unit in existence
Elements: Elements are only made out of 1 singular type of atom
Compound: Where two more different elements are chemically bonded together
Mixture: Where two or more different substances aren't chemically bonded
Molecules: Where two or more atoms are chemically bonded.
Chemical Formulae
Chemical formulae are the way you present out a substance using the Periodic Table.
An example of this is a substance with two hydrogen atoms and one oxygen atom.
First of all, we need to correlate the names of the elements to its chemical symbol: Hydrogen ->
H, Oxygen ->O
Second of all you need to find out how many atoms of each are needed e.g. hydrogen has 2
atoms, oxygen has 1 atom
If we have two hydrogen atoms, we take the chemical symbol then write a 2 next to it e.g. H2.
And then we add a O at the end to represent the 1 oxygen atom
So, two hydrogen atoms and one oxygen atom are H 2O.
