3.1.3 - Bonding

Question 1

Ionic compound solubility

Answer 1

• Dissolve in water molecules as they are polar,
• Attract the positive and negative ions separately to break up the structure

Question 2

Why do ionic compounds have high melting/boiling points? (2)

Answer 2

• Many strong electrostatic forces between oppositely charged ions.
• Lots of energy is needed to break these forces.

Question 3

Ionic compound conductibility (2)

Answer 3

• Conduct electricity when molten or dissolved
• ions free to move around/carry charge.

Question 4

What is a dative covalent bond?

Answer 4

A shared pair of electrons which has been provided by one of the bonding atoms only

Question 5

Why does graphite conduct electricity?

Answer 5

• One electron is delocalised per atom, as every carbon atom shares only 3 electrons
• One electron per atom is free to move between layers and carry charge.

Question 6

Why is diamond good at heat conductivity?

Answer 6

• Tightly packed
• Rigid arrangement

Question 7

Shapes of molecules

Answer 7

linear, bent, trigonal planar, tetrahedral, trigonal bipyramidal (diagram)

Question 8

Electronegativity trend

Answer 8

As you go up and to the right, electronegativity increases (excluding noble gases)

Question 9

VdW forces and (branched) hydrocarbons (3)

Answer 9

• Branched hydrocarbons cannot pack together as close,
• Weakens VdW forces between chains
• Lowers the boiling point

Question 10

Describe hydrogen bonding (2)

Answer 10

• Strong type of intermolecular dipole-dipole attraction.
• Occurs between hydrogen and F, O or N

Question 11

Describe metallic bonding

Answer 11

Strong electrostatic attraction between positive metal ions, and negative delocalised electron cloud

Question 12

What is the charge and melting point relationship?

Answer 12

The more electrons each atom can donate, the stronger the bond between positive metal ion and delocalised electron cloud, higher melting point.

Question 13

Why do permanent dipole-dipole interactions occur? (2)

Answer 13

• Difference in electronegativity results in bond polarity
• Results in attraction between the delta positive of one molecule and delta negative of another

Question 14

Why are some compounds with high electronegative difference, not polar?

Answer 14

Those with symmetrical geometry and charges cancel out, leaving no net dipole