Shapes of Molecules, Ions Bond Polarity, structure & Intermolecular Forces

Question 1

Why does a lone pair of electrons repel more than a bonded pair?

Answer 1

The lone electron is slightly closer to the central atom which contains the positive protons and it also occupies more bonding space so it repels more strongly

Question 2

What is the bond angle of a tetrahedral molecule? Example?

Answer 2

109.5

CH4

Question 3

What is the bond angle of a pyramidal molecule? Example

Answer 3

107

NH3

Question 4

What is the bond angle of a non-linear molecule? Example

Answer 4

104.5

H20

Question 5

What is the bond angle of a linear molecule? Example?

Answer 5

180

O2

Question 6

What is the bond angle of a trigonal planar molecule?

Answer 6

120

Question 7

What is the bond angle of a tetrahedral molecule?

Answer 7

109.5

Question 8

What is the bond angle of a octahedral molecule?

Answer 8

90

Question 9

What is are the main rules in electron repulsion theory?

Answer 9

Electrons repel each other and are arranged to minimise repulsion as much as possible

The electron repulsion is definite in terms of positioning so the shape of the electron is determined by this

Question 10

Why are molecules are non-polar?

Answer 10

They either:
Are the same atoms bonded together
Or
The two atoms have the same/similar electronegativity

Question 11

When drawing charges on molecules, usually, what charge is hydrogen?

Answer 11

Positive

Question 12

How can you determine which atom is positive and which negative in a polar molecule?

Answer 12

The atom with the largest electronegativity has the negative charge

Question 13

What is electronegativity?

Answer 13

The ability of an atom to attract a pair of electrons to itself

Question 14

Which elements are classed as being very electronegative?

Answer 14

Fluorine, nitrogen, oxygen

Question 15

Which type of intermolecular forces are temporary?

Answer 15

Van Der Waals

Question 16

What is the difference between a polar and non-polar covalent bond? What causes this?

Answer 16

Non-polar covalent bonds equally share a pair of electrons whereas polar covalent bonds unequally share electrons due to differences in electronegativity

Question 17

When does a dipole-dipole force occur?

Answer 17

When a partial charge from within a molecule has uneven distributions of electrons which is permanent

Question 18

What are the properties of simple molecular structures?

Answer 18

Weak intermolecular forces

No delocalised electrons

Question 19

Why can’t ice conduct electricity?

Answer 19

It’s H+ ions don’t travel around quick enough

Question 20

Why is ice strong?

Answer 20

H+ and O- ions form strong intermolecular forces

Question 21

Give the properties of a giant covalent structure like diamond?

Answer 21

Strong covalent bonds 
High melting and boiling point
Lots of energy required to change state 
Giant lattice structure 
No delocalised electrons

Question 22

Which structure does graphite have? Can it conduct electricity?

Answer 22

Giant covalent

Yes, because it has delocalised electrons

Question 23

Which two structures contain no delocalised electrons?

Answer 23

Simple molecular

Giant covalent

Question 24

Why does a metallic structure have a high strength?

Answer 24

Attraction between delocalised electrons and ions causes high strength which require a lot of energy to be broken

Question 25

Why is a simple molecular structure insoluble?

Answer 25

It’s ions aren’t attracted to oxygen or hydrogen

Question 26

What is the difference between intermolecular and intramolecular forces?

Answer 26

Inter - forces between (e.g: hydrogen)

Intra - forces within (e.g: covalent)

Question 27

List the intermolecular forces from weakest to strongest?

Answer 27

Van Der Waals
Dipole-dipole
Hydrogen

Question 28

Why are dipole-dipole forces permanent?

Answer 28

Large differences in electronegativity cause permanent in-built dipoles as molecules attract each other more strongly than if they relied on van Der waals forces

Question 29

How do Van Der Waals forces arise?

Answer 29

Mobile electrons which have a slightly positive and slightly negative side become attracted to the closest opposing attraction and flip, inducing a dipole. These are temporary as they’re moving so the dipoles are constantly moving

Question 30

Where does hydrogen bonding occur? What must be present in order for this force to occur?

Answer 30

Between atoms which have a high electronegativity and hydrogen
Usually between; H, O, F or N
There must be a lone pair involved

Question 31

Which type of structures can non metals be?

Answer 31

Simple molecular

Giant covalent

Question 32

What structure can a non-metal and a metal be?

Answer 32

Giant ionic lattice

Question 33

What is a dative covalent bonding?

Answer 33

Bonds formed when non-metals share electrons, a covalent bond formed when both electrons in the electron pair come from the same atom

Question 34

Which electron pairs have the most repulsion and which have the least?

Answer 34

Bonding pair and bonding pair (least)
Bonding pair and lone pair
Lone pair and lone pair (most)