2.1 Periodicity

Question 1

In what order are elements arranged in the periodic table

Answer 1

Increasing atomic number

Question 2

Period

Answer 2

Row of elements

Question 3

Group

Answer 3

Column or elements

Question 4

Periodicity

Answer 4

The study of repeating trends and patterns in the periodic table

Question 5

Trend in first ionisation energy across a period

Answer 5

Increases across the period with a dip between group 2 and 3 and between group 5 and 6

Question 6

First ionisation energy

Answer 6

The energy needed to remove one electron from each atom in one mole of gaseous atoms

Question 7

Why does first ionisation energy increase across a period

Answer 7

• nuclear charge increases
• similar shielding
• nuclear attraction on outer electron increases

Question 8

Why does atomic radius decrease across the period

Answer 8

• nuclear charge increases
• same shielding
• attraction on outer electron increases

Question 9

What are cations like in size relative to their atoms

Answer 9

Smaller

Question 10

Why are cations smaller than their atoms

Answer 10

Lose electrons and so lose a shell

Same protons attracting fewer electrons

Question 11

What are anions like in size relative to their atoms

Answer 11

Larger

Question 12

Why are anions larger than their atoms

Answer 12

Gain electrons so same number of protons attracting more electrons

Question 13

Electronegativity

Answer 13

The power of an atom to attract the pair of electrons in a covalent bond

Question 14

What is the trend in electronegativity across a period

Answer 14

Increase

Question 15

Why does electronegativity increase across a period

Answer 15

Number of protons increase
Electrons in same shell- similar shielding

Attraction on outer electrons increases

Question 16

Why is there variation in melting and boiling points across a period

Answer 16

Changes in structure and bonding

Question 17

What is the structure in Na, Mg and Al

Answer 17

Giant lattice

Question 18

What bonding Na, Mg and Al

Answer 18

Metallic

Question 19

Trend in boiling and melting points from Na to Al

Answer 19

Increase

Question 20

Why do melting and boiling points increase from Na to Al

Answer 20

Metallic bonds increase

Charge increases

More delocalised electrons

Attraction between ions and delocalised electrons increases

Question 21

structure and bonding of silicon

Answer 21

giant covalent

Question 22

melting and boiling point of Si

Answer 22

v high

Question 23

why does Si have high m and b point

Answer 23

huge numbers of strong covalent bonds needed to be broken

Question 24

structure of phosphorus, sulphur and chlorine

Answer 24

simple covalent

Question 25

melting/boiling points of sulphur, phosphorus and chlorine

Answer 25

relatively low

Question 26

why are melting/boiling points relatively low in phosphorus, sulphur and chlorine

Answer 26

weak VDW forces between molecules need to be overcome

Question 27

in what order to boiling/melting points increase in sulphur, phosphorous and chlorine

Answer 27

chlorine>phosphorus>sulphur

Question 28

why do boiling points increase from chlorine>phosphorus>sulfur

Answer 28

molecules get larger so more electrons involved in bonding- VDWs greater

Question 29

structure of Ar

Answer 29

atoms

Question 30

melting/boiling point Ar

Answer 30

very low MP/BP

Question 31

why does argon have a low melting/boiling point

Answer 31

monoatomic- very weak VDWs between atoms