Structure And Bonding PPQs

Question 1

Which intermolecular force depends on to a large extent on the number of electrons in a molecule?

Answer 1

LONDON FORCES

Question 2

H bonds are the…

Answer 2

Strongest intermolecular force

Question 3

Sodium sodium chloride can both be good conductors of electricity.

Under what conditions to the substances conduct electricity?

Compare the method of conductivity in each case. (3)

Answer 3

Sodium - conducts when solid and molten
Sodium chloride - conducts only when molten

Charge carriers in sodium are delocalised electrons but in sodium chloride they are ions

Question 4

Explain why the melting point of magnesium is much higher than that of sodium (3)

Answer 4

Magnesium ion has a larger charge than sodium ions (2+ vs 1+)

Mg2+ ions are smaller than Na+ ions

So Mg2+ ions have a greater attraction to the sea of delocalised electrons

Question 5

Two forces of repulsion in ionic lattice

Answer 5

Electrons

Ions of same charge

Question 6

The lattice composed of the ions Mg2+ and O2 is stronger than the lattice composed of the ions Mg+ and O.

Explain in terms of charges on the on size of the cations, why this is (3)

Answer 6

Mg2+ and O2- have a higher charge

Mg2+ smaller than Mg+

Question 7

Suggest why the melting temperature of magnesium oxide is higher than that of magnesium chloride even though both almost 100% ionic

Answer 7

Magnesium oxide has O2- charge whereas magnesium chloride has Cl- charge - oxide ion has a larger charge

So forces of attraction BETWEEN IONS in the magnesium oxide are stronger (stronger ionic bonding)

So more energy required to break ionic bonds in MgO

Question 8

Explain why there are no hydrogen bonds between ethanthiol molecules (1)

Answer 8

H bonds can only occur between H and either N, O or F DUE TO HIGH DIFFERENCE IN ELECTRONEGATIVITY

Question 9

Explain how nitrogen oxides cause damage. (3)

Answer 9

Form when petrol burnt in car engines

Reacts with water to form acid rain

Reacts with limestone and corrodes

Question 10

-2258 vs -2223 experimental vs theoretical

Would u expect it’s bonding to match the ionic model?

Answer 10

No

Difference in values
So not fully ionic (covalent character in lattice)

Question 11

Suggest why aqueous solutions of calcium chloride and barium chloride of the same molar concentration have different electrical conductivities. (1)

XXX?

Answer 11

Cations are different sizes