Structure and Bonding

Question 1

What is the structure of a monoatomic?

Answer 1

A simple atom

Question 2

What is the structure of a simple molecular?

Answer 2

• Atoms covalently bonded in molecules with weak intermolecular forces
• Substances with simple molecular structures are gases or liquids or solids with low melting points

Question 3

What is the structure of a giant covalent? (Acts like a diamond not graphite)

Answer 3

A giant lattice bonded together by strong covalent bonds.

Question 4

What is an ionic structure?

Answer 4

A giant lattice of alternating positive and negative ions, held together by a strong electrostatic attraction between the oppositely charged ions

Question 5

What is a metallic structure?

Answer 5

A giant structure made up of layers of positive ions surrounded by a sea of delocalised electrons.
(There is a strong electrostatic attraction between the positive ions and the electrons)

Question 6

What is an ionic bond?

Answer 6

• A strong electrostatic attraction between two oppositely charged ions.
• Occurs between a metal and non-metal.

Question 7

Why does an ionic compound have a high boiling and melting points?

Answer 7

• There is strong electrostatic attraction between the positive and negative ions which need a large amount of energy to be overcome.
• NaCl lower melting point and boiling point than MgO as lower charges, a weaker electrostatic attraction, less energy is needed to break the bonds apart than in MgO.

Question 8

Why does an ionic compound not conduct electricity?

Answer 8

1. Ionic compounds do not conduct electricity as their ions are locked in a rigid structure in a giant lattice so are not free to move and so cannot flow and carry the charge
2. However ionic compounds do conduct electricity when aqueous (or in solution) or molten as then their ions are no longer locked in a rigid structure in the lattice and so the ions are now mobile and so can flow and carry the charge

Question 9

Are ionic compounds soluble in water?

Answer 9

yes

Question 10

Why does a giant covalent substance, such as a diamond have a high melting and boiling point?

Answer 10

• Giant covalent substances have many strong covalent bonds, which need a large amount of energy to be broken apart
• Higher mp and bp in diamond as there are more bonds than in graphite as there are 4 bonds for every carbon atom rather than 3 like in graphite

Question 11

Does diamond conduct electricity?

Answer 11

No, as diamond is an electrical insulator as there are no spare electrons to carry the charge (no charged particles)

Question 12

Is diamond and graphite soluble in water?

Answer 12

Does not dissolve in water or in any other solvent because of strong covalent bonds, which needs a large amount of energy

Question 13

Why do simple molecular substances have low melting and boiling points?

Answer 13

The molecules in a simple molecular substance are attracted by weak intermolecular forces and so only a small amount of energy is needed to overcome these forces (weak intermolecular forces between the molecules)

Question 14

Why do simple molecular substances not conduct electricity?

Answer 14

They have no charged particles/no ions/no delocalised electrons (even though they can move)

Question 15

How does molecule size affect melting and boiling point?

Answer 15

The bigger the molecule, the stronger the forces and so the higher the (melting and) boiling point

Question 16

What does it mean by ductile?

Answer 16

Can be pulled into a wire

Question 17

What does it mean by malleable?

Answer 17

Can be hammered into shape

Question 18

Why do metals have a high melting and boiling point?

Answer 18

• A large amount of energy is needed to overcome to strong electrostatic attraction between the positive metal ions and the electrons
• Some metals are magnetic
• Metals are solids at room temperature except for mercury
• More positive ions and electrons in Mg that Na

Question 19

Why is a metal malleable?

Answer 19

• As the layers can slide over each other, unlike in an ionic compound where the ions are held in a rigid structure, and if the layers did slide over each other it would be positive over positive :(. Whereas if the metal layers did slide over each other it would be a positive over positive (which would not affect its structure?)
• This means that metals can be hammered or rolled into flat sheets

Question 20

Describe the structure of graphite

Answer 20

Each carbon atom has three (covalent) bonds, and has a delocalised electron

Question 21

What are the properties of graphite? Where is it used?

Answer 21

• Graphite is soft and slippery as there are only weak forces of attraction between the layers, so they are able to slide off
• Graphite is used in pencils and powdered graphite is used to LUBRICATE locks

Question 22

Is diamond or graphite more dense?

Answer 22

Graphite is less dense than diamond as the layers in graphite are relatively far apart. The distance between the graphite layers are more than twice the distance between atoms in each layer

Question 23

Does graphite conduct electricity?

Answer 23

Graphite can conduct electricity as the delocalised electron can move and carry an electrical charge (graphite is the only GCS that can conduct electricity)

Question 24

What are the properties of diamond? Where is it used?

Answer 24

• Diamonds are hard as the carbon atoms are held together with very strong covalent bonds
• Diamonds are used to tip the saw blades in high speed CUTTING tools used on stone or concrete

Question 25

What is an example of a giant covalent structure?

Answer 25

Silicon dioxide

Question 26

What is covalent bonding?

Answer 26

• The formation of a covalent bond by the sharing of a pair of electrons between two atoms
• Covalent bonding is a strong attraction between the bonding pair of electrons and the nuclei of the atoms involved in the bond

Question 27

Describe MgCl

Answer 27

For every magnesium ion there are 2 chloriDE ions

Question 28

What do you need to watch out for when guessing the mystery element?

Answer 28

Mercury is liquid at room temperature but metal

Question 29

Are metals good conductors or heat and electricity?

Answer 29

• As each atom contributes a delocalised electron to the sea of delocalised electrons which are able to move and carry the charge
• The free electrons carry electrical current and heat energy though the material, so metals are good conductors of electricity and heat

Question 30

Describe covalent bonding

Answer 30

• Occurs between non metals only with a shared pair of electrons
• Diatomic is when there is a little two e.g. Cl2
• There is no loss of electrons, they are just put ‘somewhere else’

Question 31

What is an ionic crystal?

Answer 31

A giant three-dimensional lattice structure held together by the attraction between oppositely charged ions