3.1.3 Bonding

Question 1

What is ionic bonding?

Answer 1

The electrostatic attraction between oppositely charged ions in a lattice

Question 2

What is a covalent bond?

Answer 2

A shared pair of electrons

Question 3

What is a coordinate bond?

Answer 3

A shared pair of electrons with both electrons supplied by one atom

Question 4

How is a covalent bond represented?

Answer 4

A line

Question 5

How is a coordinate bond represented?

Answer 5

An arrow

Question 6

What is metallic bonding?

Answer 6

The attraction between delocalised electrons and positive ions arranged in a lattice

Question 7

What are bonding and lone pairs? (3)

Answer 7

Charge clouds that repel each other
Bonding pairs - shared pair of electrons
Lone pairs - unshared pair of electrons

Question 8

How do electrons in an outer shell arrange themselves?

Answer 8

As far apart as possible to minimise repulsion

Question 9

Which sort of repulsion is greatest?

Answer 9

Lone pair - lone pair

Question 10

Which repulsion causes the greatest bond angles?

Answer 10

Lone pair - lone pair

Question 11

Bond angles - Linear

Answer 11

180°

Question 12

Bond angles - Trigonal Planar

Answer 12

120°

Question 13

Bond angles - Tetrahedral

Answer 13

109.5°

Question 14

Bond angles - Trigonal Pyramidial

Answer 14

107°

Question 15

Bond angles - Bent (2 lone pairs)

Answer 15

104.5°

Question 16

Bond angles - Bent (1 lone pair)

Answer 16

Slightly less than 120°

Question 17

Bond angles - Trigonal Bipyramidial

Answer 17

120° / 90°

Question 18

Bond angles - Seesaw

Answer 18

102° / 86.5°

Question 19

Bond angles - T-shaped

Answer 19

87.5°

Question 20

Bond angles - Octahedral

Answer 20

90°

Question 21

Bond angles - Square Pyramidial

Answer 21

90°

Question 22

Bond angles - Square Planar

Answer 22

90°

Question 23

What is electronegativity?

Answer 23

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

Question 24

How does a polar bond form?

Answer 24

When two atoms of different electronegativities are covalently bonded, the electron distribution is unsymmetrical

Question 25

How do polar bonds produce polar molecules?

Answer 25

If charge s distributed unevenly across a whole molecule, the molecule will have a permanent dipole

Question 26

Why do some molecules with polar bonds not have a permanent dipole?

Answer 26

The partial charges in the molecule cancel out

Question 27

What are Van der Waals forces? (4)

Answer 27

Electrons in charge clouds are constantly moving They are more likely to be in one position at any one time, forming a temporary dipole This induces a dipole in nearby molecules, creating an attraction between them As the electrons are constantly moving, dipoles are being created and destroyed all the time

Question 28

What makes Van der Waals forces stronger? (2)

Answer 28

``` Larger molecules (larger electron clouds) Long, straight molecules ```

Question 29

What is hydrogen bonding? (4)

Answer 29

Strongest intermolecular force Happens when hydrogen is covalently bonded to oxygen, fluorine or nitrogen F, N and O are very electronegative so bonding electrons are attracted away from hydrogen Due to polarity of bond and high charge density in hydrogen (small molecule), the H atoms form weak bonds with lone pairs of electrons on F, N or O atoms in other molecules

Question 30

How does hydrogen bonding affect properties of substances?

Answer 30

High melting and boiling points as extra energy is needed to break the hydrogen bonds

Question 31

Why is ice less dense than water? (2)

Answer 31

When liquid water cools to form ice, the molecules make more hydrogen bonds as they arrange themselves into a regular lattice As hydrogen bonds are relatively long, the distance between molecules is greater, on average, in ice so ice is less dense

Question 32

Why are metals malleable?

Answer 32

There are no bonds holding specific ions together so they can slide over each other and be shaped easily

Question 33

How do simple covalent structures melt or boil?

Answer 33

The weak intermolecular forces are overcome

Question 34

How are macromolecules melted or boiled?

Answer 34

The strong covalent bonds are broken

Question 35

How can the type of structure of an unknown substance be determined?

Answer 35

Carry out experiments to test its physical properties (electrical conductivity, melting/boiling point, solubility in water)