Molecular Substances

Question 1

Explain the structure and bonding of molecular substances

Answer 1

Molecular substances are made up of molecules with weak intermolecular bonds between them

Question 2

Explain the conductivity of molecular substances

Answer 2

Molecular substances have all their valance electrons held in a fixed position, this means they are not free to move and therefore can not conduct electricity

Question 3

Explain the solubility of molecular substances (polar to polar)

Answer 3

The slightly positive end of the solid polar molecule will be attracted to the slightly negative end of the solvent, and slightly negative end of the solid polar molecule will be attracted to the slightly positive end of the solvent. This attraction is greater than the attraction between the solid molecules, therefore the attractive forces overcome and it is soluble

Question 4

Explain the solubility of molecular substances (non-polar to non-polar)

Answer 4

The attractive forces between one non polar molecule and the other non polar molecule are greater than the attractive forces between the solid non-polar molecule, therefore the attractive forces between the solid non-polar molecules are overcome and it is soluble

Question 5

Explain the solubility of molecular substances (polar to non-polar)

Answer 5

The attractive forces between polar and non polar molecules is not as strong as the attractive forces between the solid polar/ non polar molecules, therefore the attraction forces between the solid polar/ non polar molecule are not overcome and it is not soluble

Question 6

Explain the Mp/Bp of molecular substances

Answer 6

Molecular substances have weak intermolecular forces, therefore not much heat energy is required to overcome the intermolecular bonds and melt/boil it. Therefore the temperature of the melting/boiling point is low

Question 7

Explain the malleability /brittleness/hardness of molecular substances (hardness)

Answer 7

Generally considered to be soft, as they are held together by weak intermolecular bonds.

Question 8

Explain the malleability /brittleness/hardness of molecular substances (brittleness)

Answer 8

When a force is applied to a molecular substance, they will hold their shape until enough force is applied to overcome and break the weak intermolecular bonds