Questions Which Went Wrong - Summer To January

Question 1

Suggest why electronegativity of the elements increases from lithium to fluoride

Answer 1

Electronegativity increases because the charge increases and the atoms get smaller

Question 2

Explain why a lot of energy is needed to melt a sample of solid lithium chloride (ionic bonding)

Answer 2

Ionic bonds are very strong due to strong electrostatic forces of attraction between positive and negatively charged ions

Question 3

Explain why iodine has a higher melting point than fluorine

Answer 3

Iodine has a bigger Mr therefore has more van der vaals forces between molecules

Question 4

Name the shape of a molecule with three bonding pains and one lone pair

Answer 4

Trigonal pyramid/pyramidal

Question 5

What is the bond angle in a trigonal pyramid/pyramidal structure with one lone pair?

Answer 5

107

Question 6

How is a dative bind formed

Answer 6

Both electrons on atom (x) are donated to atom (y) -specify these

Question 7

What is the shape of a Cl3+ ion?

Answer 7

Angular, two bonding pairs, two lone pairs

Question 8

Explain why AsCl4+ has a bond angle of 109.5

Answer 8

There are four bonding pairs around As (tetrahedral structure) and all the bonding pairs repel equally

Question 9

Suggest why graphene is an excellent conductor of electricity

Answer 9

Each carbon atom is bonded to three other carbon atoms, leaving a delocalised electron which can flow through the crystal and carry charge

Question 10

Explain, in terms of structure and bonding why titanium has a high melting point

Answer 10

There is strong attraction between positive ions and delocalised electrons

Question 11

Suggest why (metal) can be hammered into different shapes

Answer 11

Layers of atoms can slide over each other

Question 12

Suggest why metal object with different shapes have similar strengths

Answer 12

Same crystal structure is retained

Question 13

Relative mass of electron

Answer 13

1/1840

Question 14

Define relative atomic mass

Answer 14

The mean mass of an atom divided by (relative to) the mass of 1/12 of an atom of carbon 12

Question 15

Define first ionisation energy

Answer 15

The energy required to remove one mole of electrons from one mole of gaseous atoms

Question 16

Why is the first ionisation of oxygen lower than that of nitrogen

Answer 16

This is due to an electron being added to an already half full shell in oxygen which results in electron, electron repulsion which lowers the energy needed to remove that electron. Nitrogen also has the added stability of a half filled she’ll of electrons in the 2p shell

Question 17

Define chain isomerism

Answer 17

The hydrocarbon chain of a compound with the same molecular formula is rearranged

Question 18

State the meaning of structural isomer

Answer 18

Structural isomers have the same molecular formula but different structural formulae (three sub divisions: position, functional group n chain)

Question 19

Give the IUPAC name for the chain isomer if but-1-ene

Answer 19

2-methylprop-1-ene

Question 20

Suggest one hazard associated with carbon particulates

Answer 20

May cause asthma or other respiratory issues

Question 21

Identify a catalyst used in a catalytic converter

Answer 21

Platinum or rhodium

Question 22

Write an equation to show how CO and NO react with each other in a catalytic converter

Answer 22

2CO + 2NO > 2CO2 + N2

Question 23

State an essential condition for free radical substitution

Answer 23

UV light

Question 24

Write an overall equation for the reaction of fluorine with fluoro methane to form tetrafluoromethane

Answer 24

3F2 + CH4F > CF4 + 3HF

Question 25

What is the role of potassium hydroxide in an elimination reaction?

Answer 25

base

Question 26

What is the role of the hydroxide ion in a nuclephillic substitution reaction?

Answer 26

Nuclephile

Question 27

State the meaning of the term electronegativity

Answer 27

The power of an atom or nucleus to attract electron density or a pair of electrons in a covalent bond