Chemistry

Summary of everything we need to know

This is how the atom is made up

• Number of protons (in nucleus)

• Number of neutrons (in nucleus)

• Number of electrons (going around outside nucleus)

Atomic Structure

This is the way the electrons are arranged in SHELLS

• 2 in first shell

• 8 in second shell

• 8 in third shell

• Remainder in fourth shell

E.g. Calcium, Ca, is 2, 8, 8, 2.

Electron Configuration

This is made up of Groups (vertical) and Rows (horizontal)

• Rows are which electron shell is being filled

• Groups are how many electrons are in the valance shell.

Periodic table

Periodic Table

• Ions have gained or lost electrons to get a FULL OUTER SHELL.

• They have a charge:• A positive charge for each

electron lost• A negative charge for each

electron gained

Ions

This is where a positive ion is attracted to a negative ion, and they combine.

• The positive charges are balanced by the negative charges.

• Use the “swap and drop” method to write polyatomic ions.

Polyatomic Ions

These are atoms which have gained or lost NEUTRONS

• An atom that has gained a neutron will gain mass

• An atom that has lost a neutron will lose mass

• Tell by the MASS NUMBER

Isotopes

Atomic and Mass Numbers

MASS NUMBER – this is the number of Protons + Neutrons

ATOMIC NUMBER – this is the number of Protons

A reaction equation says the products and the reactants

• Reactants are the 2 things that you start with

• Products are the things that you end with

• Reactant 1 + Reactant 2 Product 1 + Product 2

Reaction equations

We write the reactants and products as words:

E.g. Magnesium + oxygen Magnesium Oxide

Word equations

Use the chemical symbols as the products and reactants.

We balance these by adding numbers in front of the products and reactants so that there are the same number of atoms on both sides of the arrow.

E.g. C2H6 + 3 ½ O2 2 CO2 +

3 H2O

Balanced chemical equations

There are 4 ways to change the rate of reaction

1. Temperature

2. Surface Area

3. Concentration

4. Catalyst

Rates of Reaction (speed of the reaction)

• There is a pH scale going from:

1 (acidic) to 7 (neutral) to 14 (basic)

• Universal indicator shows pH with a colour:

red (acidic) to green(neutral) to blue/purple (basic)

Acid – Base Reactions

Acids and bases react together and give/receive IONS

• Acids always give HYDROGEN

• Bases give (usually) Hydroxide or Carbonate.

Acid – Base Reactions

This is an acid base reaction where the acid neutralises the base – and vice versa.

Leaving pH around 7

Not all acid base reactions are neutralisation reactions.

Neutralisation Reaction