Jan 2018

Question 1

5.1. Give the meaning of the term relative atomic mass (2)

Answer 1

(1) Average/mean mass of 1 atom (of an element)
(2) 1/12 mass of one atom of 12C

Question 2

6.2. Ca(NO3)2 —-> 2CaO + 4NO2 + O2
Suggest why it’s difficult to prepare a pure sample of nitrogen dioxide by this method (1)

Answer 2

(1) Difficult to separate two gases

Question 3

7.2. Identify the element in Period 2 that has the highest first ionisation energy. Explain. (3)

Answer 3

(1) Neon
(2) Large(st) number of protons / large(st) nuclear charge
(3) Same amount of shielding / same number of shells / same
number of energy levels

Question 4

7.6. Explain why the boiling point of CF4 is very low. (2)

Answer 4

(1) van der Waals/vdw forces between the molecules
(2) that are very weak (and easily broken by heat)