3.1.1 periodicity

Question 1

How is the periodic table arranged?

Answer 1

Elements are arranged in order of increasing atomic number.
Into vertical columns- each group has atoms with the same number of outer-shell electrons and similar properties.

Question 2

What is periodicity?

Answer 2

A repeating trend in properties of elements across each period.

Question 3

What is the periodic trend in electron configuration across periods 2 and 3?

Answer 3

Across period 2, the 2s sub-shell fills with two electrons, followed by the 2p sub-shell with six electrons.
Across period 3, the same pattern of filling is repeated for the 3s and 3p sub-shells.

Question 4

What blocks can the period table to divided into?

Answer 4

Blocks s, p, d, and f.
S- groups 1-2.
P- groups 3-12.
D- groups 13-18
F- everything else.

Question 5

What is meant by first ionisation energy?

Answer 5

The first ionisation energy is the energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one moles of gaseous 1+ ions.

Question 6

How does atomic radius affect the attraction between the nucleus and outer electrons?

Answer 6

The greater the distance between the nucleus and the outer electrons, the less the nuclear attraction.

Question 7

How does nuclear charge affect attraction between the nucleus and the outer electrons?

Answer 7

The more protons there are in the nucleus of an atom, the greater the attraction between the nucleus and the outer electrons.

Question 8

How does electron shielding affect attraction between the nucleus and the outer electrons?

Answer 8

Electrons are negatively charged and so inner-shell electrons repel outer-shell electrons. This repulsion reduces the attraction between the nucleus and the outer electrons.

Question 9

What is the second ionisation energy?

Answer 9

The second ionisation energy is the energy required to remove one electron from each ion in one mole of gaseous 1+ ions of an element to form one mole of gaseous 2+ ions.

Question 10

What does a large increase in ionisation energy suggest?

Answer 10

Suggests that the electron that has been removed must be from a different shell.

Question 11

What are the two key patterns in the first ionisation energy for the first 20 elements?

Answer 11

A general increase in first ionisation energy across each period.
A sharp decrease in first ionisation energy between the end of one period and the start of the next period.

Question 12

What is the trend in first ionisation energy down a group?

Answer 12

Atomic radius increases.
More inner shells so shielding increases.
Nuclear attraction on outer electrons decreases.
First ionisation energy decreases.

Question 13

What is the general trend in first ionisation energy across a period?

Answer 13

Nuclear charge increases.
Same shell: similar shielding.
Nuclear attraction increases.
Atomic radius decreases.
First ionisation energy increases.

Question 14

What is metallic bonding?

Answer 14

Metallic bonding is the strong electrostatic attraction between cations and delocalised electrons.

Question 15

What is the structure of metallic bonding?

Answer 15

The cations are fixed in position, maintaining the structure and shape of the metal.
The delocalised electrons are mobile and are able to move throughout the structure.

Question 16

What are the general properties of metals?

Answer 16

Strong metallic bonds- attraction between positive ions and delocalised electrons.
High electrical conductivity.
High melting and boiling points.

Question 17

Why do metals have electrical conductivity?

Answer 17

When a voltage is applied across a metal, the delocalised electrons can move through the structure, carrying the charge.

Question 18

Why do metals have high melting and boiling points?

Answer 18

High temperatures to provide the amount of energy needed to overcome the strong electrostatic attraction between the cations and electrons.

Question 19

Why do metals not dissolve?

Answer 19

Metals would reaction rather than dissolve.

Question 20

What are the properties of giant covalent structures?

Answer 20

High melting and boiling points- covalent bonds are strong.
Insoluble- covalent bonds are too strong to be broken by solvents.
Non-conductors of electricity (except graphene and graphite)- no free moving delocalised electrons.

Question 21

What are some giant covalent lattices?

Answer 21

Silicon.
Graphite.
Graphene.
Diamond.

Question 22

What are the melting point trends across period 2 and 3?

Answer 22

The melting point increases from group 1 to group 14.
There is a sharp decrease in melting point between group 14 and group 15.
This change is due to a change from giant to simple molecular structures.
Giant structures have strong forces to overcome so have high melting points, whereas simple molecular structures have weak forces to overcome so have lower melting points.