Exam qs Joyston De Souza has gotten wrong

Question 1

Explain how ions are detected and relative abundance is measured in a TOF mass
spectrometer.

Answer 1

ion hits the detector and gains an electron
Abundance is proportional to (the size of) the current

Question 2

Explain why the second ionisation energy of calcium is lower than the second ionisation
energy of potassium

Answer 2

In Ca(+) (outer) electron(s) is further from nucleus
More shielding (in Ca+

Question 3

Does solubility increase or decrease down group 2

Answer 3

decrease

Question 4

What is the molecular formula for Hydroxide

Answer 4

(OH)2

Question 5

State how, if at all, the chemical properties of isotopes differ.

Answer 5

No difference in chemical properties
Because all have the same electronic structure (configuration)
OR they have the same number of outer electrons

Question 6

Describe the structure of and bonding in graphite and explain why the melting point of graphite is very high (4)

Answer 6

• Each carbon atom in graphite is bonded to three other carbon atoms.
• These carbon atoms are linked by covalent bonds - which are very strong.
• Graphite is arranged in hexagonal rings and between each layer there are Van der Waals intermolecular forces which are weak in comparison to the covalent bonds.
• For each carbon atom there is a delocalised electron - due to it only forming three bonds.

Question 7

Explain why Iodine vaporises when heated gently

Answer 7

Iodine has VDW forces which are weak and require little energy to break

Question 8

name the type of bond formed between n and al in h3nalcl3 and explain how this bond is formed

Answer 8

• The bond formed between N and Al in H3NAlCl3 is a dative covalent bond.
• Nitrogen donates one of its lone pairs of electrons to the aluminum, forming a bond

Question 9

Explain, in terms of electronegativity, why the boiling point of H2S2 is lower than H2O2

Answer 9

Electronegativity of S lower than O
No hydrogen bonding between H2S2 molecules

Question 10

Suggest why the electronegativity of the elements increases from lithium to fluorine.

Answer 10

More protons / bigger nuclear charge
Same or similar shielding

Question 11

explain how the strongest type of intermolecular force arises
between two molecules of ammonia.

Answer 11

Large electronegativity difference between N + H
Forms N δ– / H δ+
Lone pair on N attracts H (δ+)