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What are atoms?

Atoms - The smallest particles from which a substance can be made from.

Everything is made from atoms.

There are over 100 types of atom.

Substances made from a one type of element is called a element.

Elements, Mixtures and Compounds.

Most substances are compounds.

Compunds are different types of atoms chemically bonded. Chemical bonds are strong, therefore hold tightly together.

Mixtures are different types of atoms physically bonded. Chemical bonds are weak, therefore do not hold tightly together. 

How to Balance Equations.

Chemical equations show the reactants and the products the new substances made in a reaction.

Hydrogen + Oxygen > Water

In chemical equations the atoms get rearranged. You can investigate what happens to the mass of reactants compared with mass of a reaction.

Symbol equations help you to see how much of each substance is involved in each reaction.

The total mass of the products formed must be equal to the total mass of the reactants - This is the Law of Conservation of Mass. Atoms can never be created or destroyed. 

State Symbols

State Symbols shows which state the substance was in at the time of the reaction.

(s) - Solids

(l) - Liquid

(g) - Gases

(aq) - Aqueous Solutions (Substances dissolved in water.)

Techniques for separation

Crystallisation=  a solute crystallises out of a saturated solution. If a solution is unsaturated some of the solvent must be evaporated before crystals formed.

Filtration= Used to seperate a sold and liquid. E.g for making pure drinking water.

Distillation= When seperating a solvent from a solution. E.g when drinking water is obtained from sea water.
Vaporisation ---> Condensation= Distillation

 Fractional Distillation= The seperation of a mixture into its components parts, or fractions, such as seperating chemical compounds by their bioling point. by heating them to a temperature at which several fractions of the compound will evaporate

Atomic Structure

              Mass           Charge

Proton      1                  +

Neutron    1                  0

electron    0.005           -

Protons + Neutrons = Mass number 

Number of protons is called atomic number.

Number of neutrons =  mass number / atomic number

Relative atomic mass = mass of one atom of the element / mass of one atom of hydrogen