Exam Revision

Question 1

In paper chromatography, the Rf value is calculated using what formula?

It is always less than what?

Answer 1

Distance moved by substance / distance moved by solvent

Always less than 1

Question 2

What is the mass and charge of alpha particles?

Answer 2

Mass 4

Charge +2

Question 3

What is the mass and charge of beta particles?

Answer 3

Mass 0.00005

Charge -1

Question 4

Definition of first ionisation energy

Answer 4

The energy required to remove 1 electron from each atom in 1 mol of gaseous atoms to form 1 mol gaseous 1+ ions

Question 5

Definition of second ionisation energy

Answer 5

The energy needed to remove 1 electron from each ion in 1mol of gaseous 1+ ions to form 1 mol of gaseous 2+ ions

Question 6

What type of process is this and why?

Answer 6

Endothermic, because you have to put energy in to achieve it

Question 7

What three factors affect ionisation energy?

Answer 7

Nuclear charge
Distance from the nucleus
Shielding

Question 8

Draw the first and second ionisation energies of oxygen

Answer 8

O(g) ➡️o+(g) + e-

O+(g) ➡️ o2+(g)+e-

Question 9

Why do ionisation energies increase within the shell?

Answer 9

Because they are removed from an increasingly positive ion - there’s less repulsion amongst the remaining electrons

Question 10

How can you find the group number by looking at ionisation energies?

Answer 10

How many electrons are there before the first big jump

Question 11

What are the two trends in first ionisation energy?

Answer 11

Decrease down groups (more shielding)

Increase across a period (more force from nucleus)

Question 12

Between which two sets of groups are there anomalies? What do these show and prove?

Answer 12

Between 2 and 3;energy … shows sub shell structure … 3 is in p orbital and 2 is in s orbital p orbital has xtra shielding that overrides nuclear charge

Drop between 5 and 6 is due to electron repulsion

Question 13

Write down the total number of electrons in the first 4 shells

Answer 13

1st 2
2nd - 2 + (3x2)= 8
3rd - 2 + (3x2) + (2x5) = 18
4th - 2+ (3x2) + (2x5) x (2x7) = 32

Question 14

When predicting hybridisation, the hybridisation numbers always add up to what?

What would 5 be?

Answer 14

The number of substituents and line pairs

Sp3d

Question 15

Name the bond angles and geometry for 2, 3, 4, 5, 6 and 7

Answer 15

180 linear

120 trigonal planar

109.5 tetrahedral

90 and 120 trigonal bipyrimidal

90 octahedral

Question 16

If a molecule has a steric number of 3 with a lone pair, what is the arrangement?

How about 4?

Answer 16

3 = bent or angular

4 = Trigonal pyramid and bent or angular for two lone pairs

Question 17

Hydrogen bonds only happen between hydrogen and which three elements?

Answer 17

Nitrogen
Fluorine
Oxygen

Question 18

Explain electronegativity

Answer 18

Ability to attract a bonding pair of electrons in a covalent bond

Question 19

What’s a Dative bond?

Answer 19

When a pair of electrons shared by two atoms (in a covalent bond) come from the same atom