Periodicity ( AS )

Question 1

How are elements in the periodic table arranged?

Answer 1

elements are arranged according to their atomic number

Question 2

what is the “period” on the periodic table?

Answer 2

the horizontal rows

Question 3

what is the “group” in the periodic table?

Answer 3

the vertical columns

Question 4

what does the group number indicate?

Answer 4

the number of outer electrons in a element

Question 5

what are the 4 blocks on the periodic table?

Answer 5

s-block
p-block
d-block
f-block

Question 6

what elements are in each block?

Answer 6

s-block= group 1 and 2
p-block= groups 3 to 8(0)
d-block= transition metals
f-block= radioactive elements

Question 7

what is periodicity?

Answer 7

the study of trends within the periodic table

Question 8

what is the trend in atomic radius along a period?

Answer 8

along a period, atomic radius decreases

Question 9

why does atomic radium decrease along a period?

Answer 9

-increase in the number of protons, so there is an increase in the nuclear charge with similar shielding
-outer electrons are pulled in closer to the nucleus because there is a greater attraction between the outer electrons and the nucleus

Question 10

what is the trend in the atomic radius down a group?

Answer 10

down the group, atomic radius increases

Question 11

why does atomic radius increase going down the group?

Answer 11

there is a increase in the number of valence shell, this increases the distance between the outer electrons and nucleus reducing the attraction

Question 12

what is the trend in ionisation energy along a period?

Answer 12

along a period, ionisation energy increases

Question 13

why does ionisation energy increase along a period?

Answer 13

-atomic radius decreases and hence nuclear charge increases
-stronger attraction between the outer electrons and the nucleus so more energy is required to remove that one electron

Question 14

what is the trend in ionisation energy going down the group?

Answer 14

going down the group, ionisation energy decreases

Question 15

why does ionisation energy decrease going down the group?

Answer 15

the atomic radius increases and shielding also increases, so there is a weaker attraction between the outer electron and nucleus, so less energy is required to remove that electron

Question 16

what does the melting point of group 3 elements depend on?

Answer 16

• the structure of the element
• bond strength

Question 17

What happens to melting points across peroid 3 between sodium and aluminium?

Answer 17

Sodium,magnesium, and aluminium are all metals with metallic bonding. Their melting point increases due to greater positive charge of their ions
●this increases the electrostatic force of attraction between the metal cations and the sea of delocalised electrons so more energy needed to break them

Question 18

Why does the melting point increase dramatically for silicon in peroid 3?

Answer 18

●Silicon is a giant covalent structure
●so it has lots of strong covalent bonds, which require a lot of energy to break

Question 19

Why does the melting point decrease in peroid 3 between phosphorus and chlorine?

Answer 19

Phosphorus, sulphur, and chlorine are all simple covalent molecules held with weak van der waals forces. Less energy is needed to overcome these weak intermolecular forces.