Bonding

Question 1

What is Ionic Bonding? (4)

Define + Explain.

Answer 1

• Ionic bonding is the strong electrostatic attraction between oppositely charged ions.
• Ionic bonds are very strong, but weaker than covalent bonds. Therefore lots of energy is needed to overcome these forces.
• Molecules bonded ionically form giant ionic lattices.

Question 2

What are the main Compound Ions? (5)

Define and list the 5 compound ions you need to know.

Answer 2

Compound ions consist of atoms from two or more elements chemically bonded together, resulting in an overall charge.

The important compound ions to know are:
* Nitrate ion (NO^3-)
* Carbonate ion (CO3^2-)
* Sulfate ion (SO4^2-)
* Hydroxide ion (OH^-)
* Ammonium ion (NH4^+)

Question 3

How do you determine the Formula Of an Ionic Compound? (3)

Answer 3

1. Identify the ions present
   (e.g. Al, O)
2. Determine the charges of each ion
   (e.g. 3+,2-)
3. Balance positive + negative charges.
   (e.g. 3 x 2 = 6, so ion is Al2O3)

Question 4

How is an ionic bond formed?

Answer 4

Electron transfer from metal to non-metal.

Question 5

Key structure of ionic compounds?

Answer 5

Giant ionic lattice with strong electrostatic forces in all directions.

Question 6

What is covalent bonding?

Answer 6

Shared pair of electrons between atoms.

Question 7

What is metallic bonding?

Answer 7

Attraction between positive metal ions and delocalised electrons.

Question 8

Why do ionic compounds have high melting points?

Answer 8

Strong electrostatic attractions require lots of energy to overcome.

Question 9

Why are ionic compounds brittle?

Answer 9

Shifting layers cause like charges to repel.

Question 10

When do ionic compounds conduct electricity?

Answer 10

When molten or dissolved (ions are free to move).

Question 11

Why do simple molecular substances have low melting points?

Answer 11

Weak intermolecular forces between molecules.

Question 12

Do simple molecular substances conduct electricity?

Answer 12

No — no free charged particles.

Question 13

Why does diamond have a high melting point?

Answer 13

Strong covalent bonds in a giant structure.

Question 14

Why does graphite conduct electricity?

Answer 14

Has delocalised electrons.

Question 15

Why is graphite soft?

Answer 15

Layers held by weak forces can slide.

Question 16

What is graphene?

Answer 16

Single layer of graphite; strong and conductive.

Question 17

What are London forces?

Answer 17

Temporary dipole–induced dipole attractions.

Question 18

What affects London forces strength?

Answer 18

Number of electrons and surface area.

Question 19

What are permanent dipole–dipole forces?

Answer 19

Attraction between polar molecules.

Question 20

What is hydrogen bonding?

Answer 20

Strong dipole attraction between H and N, O, or F.

Question 21

Order of IMF strength?

Answer 21

Hydrogen bonding > dipole–dipole > London forces.

Question 22

What is electronegativity?

Answer 22

Ability of an atom to attract electrons in a bond.

Question 23

What causes polarity?

Answer 23

Difference in electronegativity.

Question 24

When is a bond polar?

Answer 24

Unequal sharing of electrons.

Question 25

What determines shape?

Answer 25

Repulsion between electron pairs.

Question 26

What is the bond angle in a linear molecule?

Answer 26

180°

Question 27

Shape and angle of trigonal planar?

Answer 27

120°

Question 28

Shape and angle of tetrahedral?

Answer 28

109.5°

Question 29

Shape of NH₃ and angle?

Answer 29

Trigonal pyramidal, 107°

Question 30

Shape of H₂O and angle?

Answer 30

Bent, 104.5°

Question 31

Why do lone pairs reduce bond angle?

Answer 31

Lone pair repulsion > bond pair repulsion.

Question 32

Difference between intermolecular and intramolecular forces?

Answer 32

Intramolecular = bonds within molecule (strong) Intermolecular = forces between molecules (weak)

Question 33

Why does iodine have a higher boiling point than chlorine?

Answer 33

More electrons → stronger London forces.

Question 34

Why does water have a high boiling point?

Answer 34

Hydrogen bonding between molecules.

Question 35

Why do metals conduct electricity?

Answer 35

Delocalised electrons can move.