1.20 understand the term molar volume of a gas and use its values (24 dm3 and 24,000 cm3) at room temperature and pressure (rtp) in calculations.

1 dm³ = 1000cm³

The best way to do these calculations is by using this triangle:

Molar Volume = 24dm³

Volume = moles x 24

moles = volume ÷ 24

24 = volume ÷moles

1.19 carry out mole calculations using relative atomic mass (Ar) and relative formula mass (Mr)

The simplest way to remember how to do these calculations is using this triangle:

Mass = Mr x Moles

Mr = Mass ÷ Moles

Moles = Mass ÷ Mr

1.18 understand the term mole as the Avogadro number of particles (atoms, molecules, formulae, ions or electrons) in a substance

A mole is 6.022 x 10²³ atoms of any element. This is Avogadro's number.

1.17 understand the use of the term mole to represent the amount of substance

A mole is a number just how a million is equal to 1,000,000 a mole is equal to 6.022 x 10²³

(This is also known as Avogadro's number)

1 mole of any element is equal to its RAM

e.g. water has a RAM of 18 and one mole of H2O weighs 18g

1.16 calculate relative formula masses (Mr) from relative atomic masses (Ar)

The Mr of a molecule or compound is calculated using this formula:

(Ar x number of that atom in molecule/compound) + (Ar x number of the other atom(s) if there are any)

e.g. Mr of HCL is (1 x 1) + (1 x 35.5) = 36.5

       Mr of H2O2 is (2 x 1) + (2 x 16) = 34 

1.15 deduce the number of outer electrons in a main group element from its position in the Periodic Table

The group in which the element is in on the periodic table shows how many electrons it has got in its outer most shell

e.g. Magnesium (Mg) is in group II and hence has 2 electrons in its outer most shell

1.14 deduce the electronic configurations of the first 20 elements from their positions in the Periodic Table

The first shell always has 2 electrons, and then on the shells can contain a maximum of 8 electrons.

In the periodic table, the row that an element is in corresponds to the amount of shells it has etc. row 3 has three orbiting shells.

Also the group that the element is in corresponds to the amount of electrons in its outer shells etc. group 3 has three electrons in its outer most shell.

An example:

Sulfur is in Group 6 Row 3 and hence it has two shells and six electrons in its outer most shell, making its electronic configuration 2.8.6