1.7: Ionic Bonding

Question 1

What does Coulomb’s Law suggest?

Answer 1

The strength of an electrostatic interaction is:
• Proportional to the size of charge
• Inversely proportion to distance²

Question 2

What is electronegativity?

Answer 2

It is the ability of an atom to attract electrons towards itself in a chemical bond

Question 3

What is electronegativity dependant on? (3)

Answer 3

• Number of protons in the nucleus
• Distance from nucleus/size of atom
• Amount of shielding from inner electrons

Question 4

Which element is most electronegative and why?

Answer 4

Fluorine - It’s small and has high nuclear charge

Question 5

What is the octet rule?

Answer 5

• Atoms tend to adjust their valence shells to 8e- by losing, gaining or sharing electrons
• All elements (except noble gases) show a strong tendancy to join with other atoms to form molecules
• d orbitals have exceptions

Question 6

What are the 3 steps in Ionic Bonding?

Answer 6

1. Formation of ions
2. Attraction between opposite charges
3. Formation of Ionic compound

Question 7

What are the properties of Ionic bond? (3)

Answer 7

• Non-directional
• Broken easily when dissolved in water and other polar solvents
(Seperated ions are solvated)
• Broken when heated - Conduct electricity when broken or in solution

Question 8

What is the overall charge of an Ionic compound?

Answer 8

Ionic compounds are not charged overall

Question 9

Why does Ionic lattice form?

Answer 9

• Every ion is attracted to all other ions with opposite charge
• This results in a repeating 3D pattern of anions and cations in the solid state
• Forms giant structure

Question 10

Define lattice enthalpy

Answer 10

• The measure of bond strength
• Enthalpy of formation - energy change of forming one mole of ionic solid from its gaseous ions

Question 11

What factors favour Ionic Bonding?

Answer 11

• Easy cation and anion formation
• Large electronegativity difference between the combining atoms
• High lattice energy of ionic compound

Question 12

What favours cation formation?

Answer 12

Low ionisation energy of the metal

Question 13

What favours anion formation?

Answer 13

• High electron affinity/electronegativity of the non-metal
• Small size of non-metal
• Low charge on anion

Question 14

Define polarisation

Answer 14

Distortion of the electron cloud of an atom

Question 15

What affects polarisation power and polarisability?

Answer 15

• Smaller and higher charged cations have higher ability of distorting electron cloud of another atom
• The larger an atom, the higher its polarisability (anions)

Question 16

What is Fajan’s rule?

Answer 16

An Ionic compound is likely to gave some covalent character if:

• The cation is highly polarising (is small and/has high charge)
• The anion is highly polarisable (is large and/has high charge)

Question 17

What are the 3 properties of pure Ionic compounds

Answer 17

1. Low positive charge (metal)
2. Large cation (metal)
3. Small anion (non metal) eg. F

Question 18

What are the properties of Ionic bonds with covenant character?

Answer 18

1. High positive charge (metal)
2. Small cation (metal)
3. Large anion (non metal)

Question 19

Learn how to work out bond orders

Answer 19

Bonding electrons- lone electrons /2

The higher the bond order, the more stable the molecular- more bonded electrons