Chapter 7 - Periodicity

Question 1

What is periodicity?

Answer 1

is the trend in properties that shows a repeating pattern across different periods

Question 2

How can elements be classified as s, p or d block?

Answer 2

according to which the sub-shell the outermost electrons are in

Question 3

What is the nuclear charge?

Answer 3

no’ of protons in the nucleus

Question 4

What is shielding?

Answer 4

Number of completed electron shields between the nucleus and outer shell

Question 5

What is the nuclear attraction?

Answer 5

The attraction between the nucleus + electrons in outer shells

Question 6

What are the trends for the atomic radius across a period?

Answer 6

Atomic radius - DECREASES
Sheilding - SAME
Nuclear Charge - INCREASES
Nuclear Attraction - INCREASES

Question 7

What are the trends for the atomic radius down a group?

Answer 7

Atomic radius - INCREASES
Sheilding - INCREASES
Nuclear Charge - INCREASES
Nuclear Attraction - DECREASING

(sheilding INCREASING leads to Nuclear attraction DECREASING

Question 8

What are the trends for the ionisation energy across a period?

Answer 8

Atomic radius - DECREASES
Sheilding - SAME
Nuclear Charge - INCREASES
Nuclear Attraction - INCREASES

therefore ionisation energy INCREASES as it pulls electrons closer to nucleus

as you go across a period the force of attraction between the nucleus + outer electron increases (nuclear attraction). 1st IE INCREASES.

Question 9

What are the trends for the ionisation energy down a period?

Answer 9

Atomic radius - INCREASES
Shielding - INCREASES
Nuclear Charge - INCREASES
Nuclear Attraction - DECREASES

(NA INCREASES bc Atomic radius + shielding outweighs increase in nuclear charge)

Question 10

What is metallic bonding?

Answer 10

is the strong electrostaic attrcation between the cations and delocalised electrons

Question 11

Describe the structure in solid metals?

Answer 11

-consists of positively charged metal ions (cations) held together by negatively charged outer shell electrons.

Question 12

How do metals conduct electricity?

Answer 12

They conduct electricity due to the delocalised electrons that are mobile and so free to move anywhere in the solid metal structure.

Question 13

Why do metals have high melting points?

Answer 13

Because of the strong electrostatic forces between the cations + electrons.
It requires a lot of energy to overcome this strong attractive force and move the ions from their position in the lattice.

Question 14

Giant covalent lattices are 3-dimensional structures of atoms that are held by what force?

Answer 14

strong covalent bonds

Question 15

In diamond what are the carbon atoms arranged in and with what bond angle?

Answer 15

TETRAHEDRAL
109.5
Each carbon atom is connected to 4 covalent bonds

Question 16

Why do Giant covalent lattices have a high melting point?

Answer 16

Covalent bonds are strong. Large quantity of energy is needed to break the strong covalent bonds

Question 17

Why do Giant covalent lattices do not conduct electricity?

Answer 17

In carbon + silicon all 4 outer shell is in covalent bonding so none available for conducting electricity.

Question 18

Why are graphene and graphite exceptions to conduct electricity?

Answer 18

there is one electron available for conductivity

Question 19

Why are Giant covalent lattices insoluble?

Answer 19

Covalent bonds holding together the atoms in lattice are far too strong to be broken by interaction with solvents

Question 20

What is the 1IE?

Answer 20

Gh