Bonding and Physical Properties

Question 1

What are the energy changes that occur when solids melt and liquids vaporise?

Answer 1

SOLIDS MELT
-“Fusion”: Particles are given more kinetic energy and so vibrate with more energy, breaking the bonds holding them together. The energy needed is called the enthalpy change of melting.
-Enthalpy refers to the heat energy change under constant pressure.

LIQUIDS VAPORISE
-“Vaporisation”: Particles are given more kinetic energy and so vibrate with more energy, breaking the bonds holding them together. The energy needed is called the enthalpy change of vaporisation.
-As with melting, there is no temperature change.

Question 2

Describe the structure and properties of ionic solids.

Answer 2

STRUCTURE
-Lattices
-Strong electrostatic attraction between ions

PROPERTIES
-High melting point and boiling point
-Conduct electricity when molten or dissolved

Question 3

Describe the structure and properties of metals.

Answer 3

STRUCTURE
-Lattice of positive ions embedded in a delocalised sea of electrons

PROPERTIES
-High melting and boiling point
-Conduct thermal energy and electrical energy
-Strong but malleable

Question 4

Describe the structure and properties of molecular solids.

Answer 4

STRUCTURE
-Molecules covalently bonded together held together by weak intermolecular forces

PROPERTIES
-Soft and break easily
-Low melting and boiling points
-Doesn’t conduct electricity. as there are no charged particles to carry charge

Question 5

Describe the structure and properties of macromolecular solids.

Answer 5

STRUCTURE
-Giant structures made up of atoms covalently bonded together
-Examples include diamond and graphite

PROPERTIES
-Diamond: Hard material, high melting temperature, does not conduct electricity because there are no free charged particles to carry charge
-Graphite: Soft material, high melting temperature due to strong covalent bonds within the material, conducts electrcicity due to delocalised sea of electrons in singular layer

Question 6

What are three types of intermolecular forces?

Answer 6

WEAKEST
van der Waals
Dipole-dipole forces
Hydrogen bonds
STRONGEST

Question 7

What are the three types of strong bond?

Answer 7

Metallic bonds
Ionic bonds
Covalent bonds