Application Questions

Question 1

Why does a solution of calcium oxide conduct electricity?

Answer 1

Ionic compounds can conduct in molten (solution) form because the ions are free to move in solution as ionic bonds in the lattice are broken and ions are seperated

Question 2

Why is solid aluminium malleable?

Answer 2

It contains delocalised electrons as part of its metallic bonding, which are free to move. Thus, metallic bonds do not break when a metal is hit, meaning they are malleable

Question 3

Why is iodine a solid but fluorine is a gas at room temperature?

Answer 3

Iodine has more electrons than fluorine, thus it has greater dispersion forces and a higher melting point,

Question 4

Why is a crystal of sodium chloride brittle and will shatter if struck sharply?

Answer 4

Ionic compounds are brittle because when struck, shearing forces are applied to the crystal lattice and like charges become close so they repel, thus the crystal breaks and shatters

Question 5

Why does methanol have a higher boiling point than methane?

Answer 5

Methanol forms dispersion forces and hydrogen bonding with other molecules, whereas methane can only form dispersion forces. Hydrogen bonding is stronger than dispersion, therefore more energy is required to break the bonds in methanol

Question 6

Explain how graphite conducts electricity?

Answer 6

Only 3 of the 4 carbon electrons are used in bonding, and the 4th valence electron from each carbon atom is delocalised within the lattice, allowing for electrical conductivity

Question 7

Why do both diamond and graphite have high melting points?

Answer 7

They both have very strong covalent bonds between the atoms, which makes it difficult to break the bonds and thus they have high melting points

Question 8

What are some examples of molecules which form polar bonds?

Answer 8

Ammonia, methane, water and hydrogen chloride (HCl)

Question 9

What are some examples of overall polar molecules?

Answer 9

Ammonia, water and hydrogen chloride (HCl)

Question 10

What are some examples of overall non-polar molecules?

Answer 10

Oxygen and methane

Question 11

What is the relationship between covalent bonds, dispersion forces and boiling points?

Answer 11

The greater the amount of covalent bonds, the more dispersion forces, thus the boiling point also increases