2. Atomic Structure and the Periodic Table

Question 1

what is the formula of the relative formula mass?

Answer 1

∑ isotope mass x isotope abundance+ ∑ isotope mass x isotope abundance / 100.

Question 2

Explain why the first ionisation energy of oxygen is lower than that of nitrogen. (3)

Answer 2

oxygen atom loses a paired electron from a 2p orbital.
nitrogen atom loses an electron from a singly occupied orbital.

Question 3

Explain why the first ionization energy of selenium is lower than that of arsenic?

Answer 3

Electron removed from orbital containing two electrons.
Increase in repulsion so electron lost more easily.

Question 4

Explain why the first ionization energy of krypton is higher than that of selenium

Answer 4

Number of protons is increasing
Outermost electron is closer to the nucleus.

Question 5

Explain why the first ionization energy of rubidium is lower than that of krypton. (2)

Answer 5

• The electron in Rb removed is further from the nucleus.
• The electron is in higher energy quantum shell.

Question 6

Explain two ways in which the physical properties of diamond and graphite differ. Refer to their structure and bonding in your answer (4)

Answer 6

Diamond is hard and graphite is soft because weak forces between the layers in graphite allow the layers to slide over one another.
Graphite conducts electricity and diamond does not because graphite has delocalised electrons which are free to move.

Question 7

State how the structure of graphene is related to the structure of graphite

Answer 7

single layer

Question 8

State a use for graphene identifying the property that makes it suitable for that use.

Answer 8

• flexible electronics as only one atom thick
• oxidation resistant layer as it is unreactive.

Question 9

Covalent bonding is best described as the electrostatic attraction between

Answer 9

two nuclei and a shared pair of electrons.

Question 10

Explain how the electrical conductivity, high melting temperature and malleability of metals depend on their structure and bonding.

Answer 10

Electrical conductivity: electrons can flow under potential difference.
High melting temperature: strong force of attraction between positively ions and negatively electrons.
Malleability: ions slide over each other while still being held by electrons.