Periodic trends in bonding and structure

Question 1

How many metals are there?

Answer 1

92

Question 2

How many non-metals are there?

Answer 2

22

Question 3

What is the structure of metals at room temperature?

Answer 3

Solid - except mercury

Question 4

What is the one constant property of metals?

Answer 4

The ability to conduct electricity

Question 5

What is metallic bonding?

Answer 5

Strong electrostatic attraction between cations and delocalised electrons

Question 6

What is the structure of a metal in metallic bonding?

Answer 6

The cations are in fixed positions, maintaining shape and structure
The delocalised electrons are mobile and able to move throughout the structure - carry charge

Question 7

How are metal atoms held together?

Answer 7

By metallic bonding in a giant metallic lattice

Question 8

What are the 3 key physical properties of metals?

Answer 8

1) Strong metallic bonds
2) High electrical conductivity
3) High melting and boiling points

Question 9

What states do metals conduct electricity in?

Answer 9

Solid and liquid

Question 10

Why do metals have good electrical conductivity?

Answer 10

The delocalised electrons can move through the structure, carrying charge

Question 11

Why do metals have high melting and boiling points?

Answer 11

High temperatures are necessary to provide the large amount of energy needed to overcome the strong electrostatic attraction between the cations and delocalised electrons

Question 12

Are metals soluble?

Answer 12

No - they don’t dissolve

Question 13

What is the structure of non-metals?

Answer 13

Simple covalently bonded molecules

Question 14

What structure do non-metals form in the solid state?

Answer 14

Simple molecular lattice held together by weak intermolecular forces

Question 15

Which non-metals form a giant covalent lattice?

Answer 15

Boron, carbon, and silicon

Question 16

Why do carbon and silicon form a giant covalent lattice?

Answer 16

They have 4 electrons in their outer shells which they use to make covalent bonds to other carbon and silicon atoms

Question 17

What structure do carbon and silicon covalent bonds make?

Answer 17

Tetrahedral structure with bond angles of 109.5 degrees by electron pair repulsion

Question 18

Are covalent bonds weak or strong?

Answer 18

Strong - difficult to break

Question 19

What are the properties of substances with a giant covalent lattice structure?

Answer 19

1) High melting and boiling points
2) Insoluble
3) Non-conductors of electricity, except graphene and graphite

Question 20

Why do giant covalent lattices have high melting and boiling points?

Answer 20

High temperatures are necessary to provide the large quantity of energy needed to break the strong covalent bonds

Question 21

Why are giant covalent lattices insoluble?

Answer 21

Covalent bonds are too strong to be broken by interaction with solvents

Question 22

Why are giant covalent lattices non-conductors of electricity?

Answer 22

All outer shell electrons are involved in covalent bonding so none are available for conducting electricity

Question 23

Why are graphene and graphite able to conduct electricity?

Answer 23

One of the electrons is available for conductivity

Question 24

What are the periodic trends in melting points across period 2?

Answer 24

Increases from group 1 to 14 (4)
Sharp decrease between group 14 (4) and 15 (5)
Melting points comparatively low from group 15 (5) to 18 (0)

Question 25

What does the sharp decrease in melting point show?

Answer 25

Marks a change from giant to simple molecular structures

Question 26

What happens to the periodic trends in periods 3 onwards?

Answer 26

The trend in melting points is repeated across period 3 and continues across the s and p blocks from period 4 onwards