Periodicity

Question 1

What are the s block elements?

Answer 1

Groups 1 and 2 where the atoms have their outermost electrons in the s or p orbitals

Question 2

What are the p block elements?

Answer 2

Groups 3-0 where the elements have their outermost electrons in p sub shells

Question 3

What are the d block elements?

Answer 3

The transition metals where the elements have their outermost electrons in the d sub shell

Question 4

What are the f block elements?

Answer 4

Lanthanides and actinides where the outermost electrons are in the f sub shell

Question 5

What is atomic radius?

Answer 5

The distance from the centre of an atom to its outermost electrons

Question 6

What is the trend in atomic radius across a period?

Answer 6

Decreases across a period

Question 7

Why does atomic radius decrease across a period?

Answer 7

Greater nuclear charge bc more protons

Electrons added to the same shell so same amount of shielding and greater effective nuclear charge

Question 8

Define first ionisation energy

Answer 8

The amount of energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous +1 ions

Question 9

What is the trend in first ionisation energy along a period?

Answer 9

Ionisation energy increases

Question 10

Why does first ionisation energy increase across a period?

Answer 10

Increased nuclear charge from proton
Same shielding bc no extra shells
Atomic radius decreases so more attraction so more energy needed to remove outer electrons

Question 11

Why is there not a steady rise in first ionisation energy along a period?

Answer 11

Because there are dips which are caused by different sub shells

Question 12

Why does first ionisation energy increase from Na to Mg?

Answer 12

More protons so more nuclear charge so more attraction so more energy needed to remove electrons

Question 13

Why does FIE dip at Al?

Answer 13

Has a 3s2p1 configuration so the p electron is unpaired, further away and has more shielding so less energy needed to remove it

Question 14

Why does FIE increase from Al to P?

Answer 14

Atomic radius decreases, greater nuclear charge and same amount of shielding so attraction is greater so more energy needed to overcome it

Question 15

Why does FIE decrease at S?

Answer 15

Because it has 4 electrons in the p sub shell so there’s one pair so increased repulsion means less energy required to remove the electron

Question 16

Why is there an increase in melting points between Na and Al?

Answer 16

More outer electrons means more electrons can be delocalised so more attraction

Question 17

Why is there an increase in melting points between Al and Si?

Answer 17

Si has a giant covalent structure so bare energy needed to overcome these bonds

Question 18

Why is there a decrease in melting points between Si and P?

Answer 18

Because P is a weak covalent molecule with only van der Waals forces holding it together

Question 19

Why is there a decrease between S and Ar?

Answer 19

Because Ar exists as atoms with weak van der Waals forces so little energy needed to overcome them.