1.3 Bonding

Question 1

What is significant about noble gases?

Answer 1

They have full outer shells

Therefore are unreactive so don’t form compounds

Question 2

What do we use to show transfer of electrons?

Answer 2

Dot and cross diagrams

Question 3

What do you do when an ion is formed?

Answer 3

Put square brackets around the diagram and put the relative charge on the outside

Question 4

What does ionic bonding consist of?

Answer 4

A non-metal and a metal forming ions by transfer of electrons

Question 5

How are ions formed?

Answer 5

When atoms gain or lose electron in order to obtain a full outer shell (or noble gas configuration)

Question 6

What is an ionic bond?

Answer 6

A strong electrostatic force of attraction between oppositely charged ions

Question 7

What is the boiling/melting point of ionic bonding? Why?

Answer 7

High Boiling/Melting Point

The strong electrostatic force of attraction between the oppositely charged ions require a great deal of heat energy to overcome

Question 8

What are some properties of ionic compounds?

Answer 8

High melting/boiling point
Brittle
No current can flow and cannot conduct electricity unless molten or in a solution
If moved the charges repel each other

Question 9

Why can ionic substances only conduct when in a solution or molten?

Answer 9

The ions need to be delocalised so they are free to move

Question 10

What is covalent bonding?

Answer 10

A bond formed between a non-metal and a non-metal consisting of shared pairs of electrons from the outer shells of each atom

Question 11

What is a covalent bond?

Answer 11

An electrostatic force of attraction between the positively charged nucleus and the negatively charged electrons in the bonding pair

Question 12

What is a co-ordinate bond?

Answer 12

A covalent bond where both the electrons in the bonding pair come from one atom

Symbol: →

Question 13

What is significant about co-ordinate bonds?

Answer 13

After formation they become indistinguishable therefore they are just the same as normal covalent bonds

Question 14

Give an example of a co-ordinate bond?

Answer 14

(In square brackets with a positive charge on the outside)

       H
        |
H -  N → H
        |
       H

Ammonium where in the co-ordinate bond both electrons came from the nitrogen

Question 15

What are the features of diamond?

Answer 15

Covalent bonding - each carbon joined to 4 other carbons 
Creating a giant lattice 
Macromolecular structure 
Very high melting point
Strong hard substance 
Doesn’t conduct electricity

Question 16

Why does diamond and graphite have a very high melting point?

Answer 16

There are lots of strong covalent bonds therefore a lot of energy is required to break them

Question 17

Why is diamond very strong? What is it’s Mohs?

Answer 17

Because each carbon is bonded to 4 other carbons

10 Mohs (mineral hardness scale)

Question 18

What are the features of graphite?

Answer 18

Covalent bonding - each carbon is joined by three other carbons
Macromolecular structure 
Very high melting point 
Soft and slippery 
Conducts electricity

Question 19

Why is graphite soft and slippery? What is it’s Mohs?

Answer 19

Because it has a layered structure so the sheets can move over each other as they have comparatively weaker van der waal forces between these layers

1-2 Mohs (mineral hardness scale)

Question 20

Why can graphite conduct electricity?

Answer 20

As there are only 3 carbons bonded to each carbon there are delocalised electrons (one from each carbon) that can move within the layers and allow current to flow

Question 21

What are diamond and graphite?

Answer 21

Allotropes

They both have the same element just arranged in a different structure

Question 22

What are some features of silicon dioxide?

Answer 22

Covalent bonding
Macromolecular structure 
High melting point (not as high as diamond or graphite)
Strong hard substance 
Doesn’t conduct electricity

Question 23

What is significant about iodine?

Answer 23

It is a molecular crystal

Question 24

What are some features of iodine?

Answer 24

Solid at room temperature 
Molecular crystal = regular structure 
Low melting/boiling point
Doesn’t conduct electricity 
Sublimes when heated gently (solid to gas)
Non-polar

Question 25

Why is iodine solid at room temperature?

Answer 25

The van der Waals forces are very strong

Question 26

How is metallic bonding formed?

Answer 26

Between a metal and a metal forming a lattice structure

Question 27

What is a metallic bond?

Answer 27

A strong electrostatic force of attraction between positive metal ions and the sea of delocalised electrons

Question 28

What are some features of metals?

Answer 28

Lattice structure 
Malleable and ductile
Conducts electricity 
Conducts heat
High boiling points

Question 29

Why are metals good conductors of electricity and heat?

Answer 29

Due to the delocalised electrons they can carry charge through the metal

Question 30

Why do metals generally have high boiling points?

Answer 30

They have a strong electrostatic force of attraction

Question 31

What does malleable and ductile mean? Why are metals like this?

Answer 31

Malleable - the layers slide due to force or stress

Ductile - stretched (into wires)

The bonding is non-directional due to delocalised electrons which allows the metal to move coherently as the sea of delocalised electrons aren’t fixed