Why is neon an unreactive element?

Argon is an unreactive element in the same group of the Periodic Table as neon, but in Period 3. It has an atomic number of 18.

Deduce the electronic configuration of argon.

• A $\mathrm{2.8.8}$
• B $\mathrm{2.8.18}$
• C $\mathrm{2.8.2.8}$
• D $\mathrm{2.2.8.6}$

Magnesium reacts with fluorine to form the ionic compound magnesium fluoride (${MgF}_2$).

Describe, in terms of electrons, how an atom of magnesium reacts with two fluorine atoms to form magnesium fluoride.

Write the formula of a magnesium ion.

In the reaction between magnesium and fluorine, both oxidation and reduction occur.

Which row shows the element that is oxidised and the element that acts as the reducing agent in this reaction?

A student uses a flame test to distinguish between separate samples of sodium chloride and copper(II) chloride.

This is the student's method.

There is one mistake in step 1 and one mistake in step 3.

• step 1 dip a nichrome wire into some concentrated nitric acid
• step 2 dip the nichrome wire into the sample
• step 3 place the wire and sample into a luminous Bunsen flame
• step 4 record the colour of the flame

Describe a correct method for step 1 and step 3.

• step 1:
• step 3:

What colour is the flame when the test on sodium chloride is carried out correctly?

• A green
• B lilac
• C yellow
• D red