The Periodic Table

Question 1

First ionisation energy:

Answer 1

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

Question 2

Answer 2

Question 3

Factors affecting ionisation energy:

Answer 3

Negative electrons are held in their shells by their attraction to the positive nucleus. To form a positive ion, energy must be supplied to an electron to overcome this attraction. Electrons in the outer shell are removed first because they experience the smallest nuclear attraction. The outer-shell electrons are furthest away from the nucleus and require the least ionisation energy

The nuclear atraction experienced by an electron depends on three factors:
- atomic radius
- nuclear charge
- electron shielding or screening

Question 4

Atomic radius (ionisation energy):

Answer 4

The atomic radius is the distance of the outer electrons from the nucleus. The larger the atomic radius, the smaller is the nuclear attraction experienced by the outer electrons. This is because the positive charge of the nucleus is essentially further away from the outermost electrons

Question 5

Nuclear charge (ionisation energy):

Answer 5

The higher the nuclear charge, the larger the attractive force on the outer electrons

Question 6

Electron shielding or screening (ionisation energy):

Answer 6

Inner shells of electrons repel the outer-shell electrons because they are all negative

• This repelling effect is called electron shielding or screening
• The more inner shells there are, the larger the shielding effect, and the smaller the nuclear attraction experienced by the outer electrons

Question 7

Successive ionisation energies:

Answer 7

Successive ionisation energies are a measure of the amount of energy required to remove each electron in turn

Question 8

Answer 8

Question 9

Why does the successive ionisation energy increase?

Answer 9

• When electrons are in the same shell, each successive ionisation energy is slightly higher than the one before. This is because there are the same number of protons (nuclear charge) attracting fewer electrons. As each electron is removed, there is less repulsion between the remaining electrons, and so the shell is drawn in closer to the nucleus. Therefore the electrons are attracted more strongly to the nucleus and more energy is required to remove them
• When the electron being removed is in a different shell, closer to the nucleus, there is a large increase in ionisation energy. This is because as the electron being removed is in a new shell much closer to the nucleus. it is more strongly attracted to it and so more energy is required to remove the electron (there is also less shielding). This large increase in IE is evidence that shells exist. This supports the Bohr model of the atom which suggests electons orbit the nucleus in shells

Question 10

Example IE graph:

Answer 10

Question 11

1^st IE graph for elements with different sub-shells:

Answer 11

Question 12

How is ionisation energy affected by removing electrons from higher/lower energy sub-shells?

Answer 12

• Being in a higher energy sub-shell means less energy is needed to remove an electron (as it’s further away from the nucleus)
• Paired electons have more repulsion than lone electrons, therefore less energy is required to remove them

Question 13

How are elements arranged in the modern periodic table?

Answer 13

Question 14

How are the rows and the columns of the periodic table categorised?

Answer 14

Question 15

What do elements in the same group have in common?

Answer 15

Question 16

What do elements in the same period have in common?

Answer 16

Question 17

Shorthand way of writing electron arrangements:

Answer 17

Question 18

Blocks in the periodic table:

Answer 18

Question 19

Relationship between atomic radius and ionisation energy on the periodic table:

Answer 19

Question 20

Why does the atomic radius increase, and the ionisation energy decrease going down a group?

Answer 20

Question 21

Why does the atomic radius decrease, and the ionisation energy increase going across a period?

Answer 21

Question 22

What are atomic properties vs bulk properties?

Answer 22

Question 23

Melting points trend across the periodic table:

Answer 23

Question 24

Metallic bonding:

Answer 24

The atoms in a solid metal are held together by metallic bonding. In metallic bonding, the atoms are ionised

• Positive ions (cations) occupy fixed positions in a lattice
• The outer-shell electrons are delocalised - they are shared between all the atoms in the metallic structure

The metal is held together by the strong electrostatic forces of attraction between all the positive ions and the negative sea of delocalised electrons

Question 25

Structure of metals:

Answer 25

A giant metallic lattice

Question 26

Melting and boiling points of metals:

Answer 26

Most metals have high melting and boiling points. A large amount of heat energy is required to overcome the strong electrostatic forces of attraction between the positive cations and the sea of delocalised electrons

Question 27

Conductivity of metals:

Answer 27

Metals are good conductors of electricity. This is because the delocalised electrons are free to move and carry charge

Question 28

Malleability and Ductility of metals:

Answer 28

Metals are both malleable and ductile
Malleable - can be hammered into different shapes
Ductile - can be draw out or stretched (into wires for example)

Question 29

Answer 29

Question 30

Group 2 elements:

Answer 30

These metals are known as the ‘alkaline earth metals’ and all have hydroxides that are alkaline solutions with a pH of around 10-12

Question 31

Electron arrangements of group 2 elements:

Answer 31

Question 32

Reactivity of group 2 elements:

Answer 32

Question 33

Why does reactivity increase down group 2?

Answer 33

Question 34

Answer 34

Question 35

Solubility of group 2 metals:

Answer 35

Question 36

Physical properties of group 2 metals:

Answer 36

Question 37

Uses of group 2 metals:

Answer 37

Question 38

What are the halogens?

Answer 38

Group 7 (17) elements

Question 39

Structure of halogens:

Answer 39

Question 40

Electronic configuration:

Answer 40

Question 41

Reactivity of halogens:

Answer 41

Question 42

Trend in boiling points of halogens:

Answer 42

Question 43

States of the halogens:

Answer 43

Question 44

Reactions of halogens:

Answer 44

Question 45

Colours of the halogens:

Answer 45

Question 46

Disproportionation:

Answer 46

Disproportionation is the oxidation and reduction of the same element in a redox reaction

Question 47

Reaction of chlorine with water (used in water purification - disproportionation reaction)

Answer 47

Question 48

Reaction of chlorine with cold dilute aqueous sodium hydroxide (bleach formation - disproportionation reaction)

Answer 48

Question 49

Answer 49

Question 50

The order of halide ion testing:

Answer 50

Question 51

The effect of adding halide precipitates to dilute/concentrated ammonia:

Answer 51