Chemical Changes and Structure: Structure and Bonding in the First 20 Elements

Question 1

What are the characteristics of metallic bonding?

Answer 1

Strong metallic bonds, high melting points and good conductors of electricity

Question 2

What are the characteristics of covalent molecular bonding?

Answer 2

Strong covalent bonds between atoms, weak LDF between molecules and sulfur, phosphorus and the fullerenes are solids as they are heavier molecules with more electrons, therefore they have stronger LDF between molecules

Question 3

Phosphorus consists of what?

Answer 3

Four phosphorus atoms joined together by covalent bonds (P4)

Question 4

Sulfur can form what?

Answer 4

Molecules where eight sulfur atoms covalently bond to form ‘puckered rings’ (S8)

Question 5

What are the characteristics of covalent network bonding?

Answer 5

Strong covalent bonds between atoms, very high melting points as the strong covalent bonds must be broken, examples include carbon (diamond and graphite), silicon and boron

Question 6

What are the characteristics of monatomic bonding?

Answer 6

The noble gases are gaseous as they have weak LDF between atoms, melting points increase as you descend the group as the atoms have more electrons and therefore stronger LDF

Question 7

Trends in reactivity of elements are related to what?

Answer 7

The number of outer electrons

Question 8

Trends in melting and boiling points can be what?

Answer 8

Related to the structure and bonding of the elements

Question 9

What happens to covalent radius going across a period?

Answer 9

It decreases

Question 10

What happens to covalent radius going down a group?

Answer 10

It increases

Question 11

Why does covalent radius decrease across a period?

Answer 11

As you go across the period there are more protons meaning the nuclear charge increases pulling the electrons in closer decreasing the size of the atom.

Question 12

Why does covalent radius increase going down a group?

Answer 12

As you go down the group there is an extra layer of electrons meaning there is increased screening or shielding which means electrons are less strongly attracted therefore increasing the covalent radius

Question 13

What happens to electronegativity going down a group?

Answer 13

It decreases

Question 14

What happens to electronegativity going across a period?

Answer 14

It increases

Question 15

Why does electronegativity decrease going down a group?

Answer 15

As you go down the group there is an extra layer of electrons, meaning the outer electrons are further from the nucleus and are less strongly attracted to the nucleus. Increased screening or shielding also occurs meaning electrons are less strongly attracted to the nucleus.

Question 16

Why does electronegativity increase across a period?

Answer 16

As you go across a period there is increased nuclear charge causing the atom to attract bonded electrons more strongly.

Question 17

What happens to ionisation energy going down a group?

Answer 17

It decreases

Question 18

What happens to ionisation energy going across a period?

Answer 18

It increases

Question 19

Why does ionisation energy decrease going down a group?

Answer 19

As you go down a group there is an extra layer of electrons meaning the distance between the outer electrons and the nucleus increases. Therefore the attraction between the electrons and the nucleus becomes weaker. Increased screening or shielding also occurs weakening the attraction of the electrons to the nucleus.

Question 20

Why does ionisation energy increase across a period?

Answer 20

As you go across a period there is increased nuclear charge meaning the attraction between the electrons and the nucleus gets stronger. Also each time the nuclear charge increases the distance between the outer electrons and the nucleus decreases. This means the attraction between the outer electrons and the nucleus becomes stronger.