Chemical bonds (2.1) (M)

Question 1

What are the three types of bonds?

Answer 1

• covalent
• ionic
• metallic

Question 2

For ionic bonding the particles are…

Answer 2

oppositely charged ions

Question 3

For covalent bonding the particles are…

Answer 3

atoms which share pairs of electrons

Question 4

For metallic bonding the particles are…

Answer 4

atoms which share delocalised electrons

Question 5

Where does ionic bonding occur?

Answer 5

in compounds formed from metals combined with non-metals

Question 6

Where does covalent bonding occur?

Answer 6

in most non-metallic elements and in compounds of non-metals

Question 7

Where does metallic bonding occur?

Answer 7

in metallic elements and alloys

Question 8

i.e. Ionic bonding

What happens when a metal atom reacts with a non-metal atom?

Answer 8

The electrons in the outer shell of the metal atom are transferred.

Metal atoms lose electrons to become positively charged ions.

Non-metal atoms gain electrons to become negatively charged ions

Question 9

The ions produced by Group 1, 2, 6 and 7 elements have the electronic structure of what?

Answer 9

a noble gas (Group 0)

Question 10

How can the electron transfer during the formation of an ionic compound be represented?

Answer 10

by a dot and cross diagram

note, in this diagram, you can draw a circle (resembling a shell) around the symbol

Question 11

What would be the ionic charge on a group 2 and group 7 ion?

Answer 11

Group 2: 2+

Group 7: -

Question 12

How is an ionic compound described?

Answer 12

a giant structure of ions (i.e. a giant ionic lattice)

Question 13

2 points

What are ionic compounds held together by?

Answer 13

strong electrostatic forces of attraction between oppositely charged ions

these forces act in all directions in the lattice

Question 14

2 ways

How can the structure of an ionic compound/lattice be represented in a 3D form?

Answer 14

Ball and stick model, 3D space filling model

Question 15

What is a common example of a giant (ionic) lattice?

Answer 15

Sodium chloride

Question 16

What is the relation in number of ions in NaCl?

Answer 16

The number of Na ions and Cl ions are equal

Question 17

What is the limitation of the dot-and-cross model to show giant ionic lattices?

Answer 17

only 2D

Does not show the shape

Does not show how ions are arranged in space (e.g. suggests NaCl is made up of pairs of sodium and chlorine ions, it is not)

Question 18

What is the limitation of the ball and stick model to show giant ionic lattices?

Answer 18

• suggests there are gaps between ions when there is not
• suggests atoms are solid inelastic spheres - they are mostly made up of of empty space
• using sticks for bonds is misleading because the forces of attraction between ions actually act in all directions
• relative size of ions compared to each other is not to scale

Question 19

What is the limitation of the 2D space-filling model to show giant ionic lattices?

Answer 19

shows the arrangement in one layer only, not the next

Question 20

What is the limitation of the 3D space-filling model to show giant ionic lattices?

Answer 20

• ions are not solid spheres
• difficult to see 3D arrangement clearly

Question 21

What are covalent bonds?

Answer 21

when atoms share pairs of electrons

Question 22

What are the bonds between atoms in covalent bonds like? (within the molecules themselves)

Answer 22

They are strong

Question 23

What are the two types of covalently bonded substances?

Answer 23

small (simple) molecules or giant covalent structures

Question 24

What is a common example of a covalently bonded substance that has very large molecules?

Answer 24

Polymers

Question 25

# 3 needed What are examples of covalently bonded substances that have giant covalent structures?

Answer 25

diamond, graphite (allotropes of carbon) and silicon dioxide (silica)

Question 26

# 4 ways How can covalent bonds in molecules and giant structures can be represented? (excluding polymers)

Answer 26

*note where shared electrons are situated in teh dot and cross diagram*

Question 27

How can polymers be represented?

Answer 27

Question 28

# 4 points Describe the structure of metals

Answer 28

* giant structures of atoms arranged in a regular pattern * layers of atoms * lattice of positive ions * with a sea of delocalised electrons * (strong) electrostatic forces of attraction between positive ions and electrons

Question 29

How would you describe the electrons in the **outer shell** of metal atoms? What does this allow?

Answer 29

delocalised and so are free to move through the whole structure

Question 30

What does the sharing of delocalised electrons in metallic bonds cause?

Answer 30

strong metallic bonds

Question 31

# 2 forms What are the forms that metallic bonds may be represented in?

Answer 31

Question 32

How do covalent bonds hold two atoms together?

Answer 32

electrostatic force of attraction between shared pair of negatively charged electrons and both positively charged nuclei

Question 33

Why can metals be bent and shaped?

Answer 33

They consist of layers, which slide over eachother

Question 34

Why should a reaction where halogen gases are given out be doe in a fume cupboard?

Answer 34

Halogen gases are toxic

Question 35

# 2 needed What is a limitation of the dot and cross diagram to represent a simple molecule?

Answer 35

does not show shape of molecule only 2D

Question 36

Why does ammonia have a low melting point?

Answer 36

Ammonia is a simple molecule/has small molecules with weak intermolecular forces it take little energy to overcome these intermolecular forces

Question 37

# 2 marks Why may corrosion reduce the electrical conductivity of a metal?

Answer 37

Metal oxide formed ions are not free to move **or** electrons cannot move through the structure *I assume this is the same for alloys*

Question 38

What happens when two atoms of potassium react with one atom of sulfur? (give answer in terms of electron transfer and state ions formed)

Answer 38

electrons transferred from potassium to sulfur two potassium atoms each lose one electron forming K⁺ ions sulfur atoms gain 2 electrons forming S^2- ions

Question 39

What are the 2 limitations of the simple model?

Answer 39

It is only 2D Particles shown as solid