Unit 1: Bonding And Structure

Question 0

Definition of a covalent bond

Answer 0

A shared pair of electrons

Question 1

Definition of ionic bonding

Answer 1

The electrostatic attraction between oppositely charged ions.

Question 2

What is the shape of a simple molecule determined by?

Answer 2

The repulsion between electron pair surrounding a central atom.

Question 3

What repels more than bonded pairs of electrons?

Answer 3

Lone pairs of electrons

Question 4

What shape and bond angle does an atom with 4 bonded pairs of electrons have?

Answer 4

Tetrahedral and 109.5

Question 5

What shape and bond angle does an atom with three bonded pairs of electrons have?

Answer 5

Trigonal planar and 120

Question 6

What shape and bond angle does an atom with 6 bonded pairs of electrons have?

Answer 6

Octahedral and 90

Question 7

What shape and bond angle does an atom with three bonded pairs of 1 lone pair of electrons have?

Answer 7

Pyramidal and 107

Question 8

What shape and bond angle does an atom with 2 bonded pairs of electrons and 2 lone pairs of electrons have?

Answer 8

Non-linear and 104.5

Question 9

By how much do you reduce the bond angle for each lone pair?

Answer 9

2.5

Question 10

Definition of electronegativity

Answer 10

The ability of an atom to attract the bonding electrons in a covalent bond.

Question 11

When may a permanent dipole arise?

Answer 11

When covalently bonded atoms have different electronegativities, resulting in a polar bond.

Question 12

Definition of metallic bonding

Answer 12

The attraction of positive ions to delocalised electrons.

Question 13

What are the anomalous properties of water resulting from hydrogen bonding?

Answer 13

1. Ice is less dense than water - The hydrogen bonds hold the water molecules apart and when the ice melts, the hydrogen bonds collapse, allowing the molecules to move closer together.
2. Water has relatively high melting and boiling points - the hydrogen bonds are relatively strong and therefore take more energy to break resulting in a higher melting and boiling point than one would expect.

Question 14

Describe the structure of NaCl

Answer 14

Giant ionic lattice with strong ionic bonding

Question 15

Describe a giant metallic lattice

Answer 15

• delocalised electrons are spread throughout structure

- positive ions occupy fixed positions in the lattice

Question 16

What are the properties of giant metallic lattices?

Answer 16

• high melting and boiling points: high temps are needed to break metallic bonds
• good electrical conductivity: delocalised electrons can move freely as solid or liquid AND positive ions can more freely when liquid
• malleable and ductile: delocalised electrons are responsible for this because they can move

Question 17

What is diamond’s structure?

Answer 17

Tetrahedral structure held together by strong covalent bonds

Question 18

What is graphite’s structure?

Answer 18

Strong hexagonal layer structure with weak van der Waals’ forces between layers

Question 19

Electrical conductivity in diamond

Answer 19

Poor conductivity because there are no delocalised electrons

Question 20

Electrical conductivity in graphite

Answer 20

Good conductivity because there are delocalised electrons between layers

Question 21

Hardness of diamond

Answer 21

Hard, tetrahedral sharpe allows external forces to be spread throughout the lattice

Question 22

Hardness of graphite

Answer 22

Soft, bonding within each layer is strong however weak van der Waals’ forces between layers allow layers to slide easily

Question 23

Definition of a dative covalent bond

Answer 23

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