Revision

Question 1

Relative atomic mass

Answer 1

Average mass of all the isotopes of an element compared to 1/12th the mass of an atom of Carbon-12

Question 2

Steps of mass spectrometry

Answer 2

Electrospray ionisation, acceleration, ion drift, ion detector, data analysis

Question 3

Describe electrospray ionisation

Answer 3

A sample is dissolved in a volatile solvent (water/methanol) and injected through a fine needle attached to high voltage power supply. The particle gains a proton, forming 1+ ion

Question 4

Acceleration

Answer 4

The ion accelerated towards a negatively charged plate

Question 5

Ion drift

Answer 5

Travel through flight tube with different velocities (because of different masses)

Question 6

Ion detection

Answer 6

When the ion hit the plate, it gains an electron, producing a current, which is detected by the detector

Question 7

Data analysis

Answer 7

Showing relative abundance and mass to charge ratio (m/z)

Question 8

Why Cr has an unusual electron configuration?

Answer 8

Half-filled 3d subshells to be more stable

Question 9

Why Fe has an unusual electron configuration?

Answer 9

Fully-filled 3d subshells to be more stable

Question 10

Definition of isoelectronic

Answer 10

Particles with same electron configuration

Question 11

Plum pudding model

Answer 11

• positive pudding (not empty spaced)
• negative electron
• no energy shell

Question 12

Covert m^3 to dm^3 and cm^3

Answer 12

1 m^3 = 1000 dm^3 = 1000000 cm^3

Question 13

Ideal gas equation with units

Answer 13

pV= nRT
(Pa)(m^3) = (mol) (JK^-1mol^-1)(K)

Question 14

Percentage yield

Answer 14

(Actual yield/ theoretical yield) x 100

Question 15

Atom economy

Answer 15

(Molecular mass of desired production/ total mass of reactants) x 100

Question 16

Why is percentage yield not 100%?

Answer 16

• lost in transfer
• not all reactants have fully reacted

Question 17

Why conical flask does not have to be fully dry?

Answer 17

Doesn’t affect the number of moles of the solute

Question 18

Why using conical flask?

Answer 18

Easier to swirl
Prevent spitting out

Question 19

Why placing a white tile?

Answer 19

To view the indicator colour more clearly

Question 20

Why the funnel needed to be removed?

Answer 20

To ensure any drops remained in it do not interfere with the titre

Question 21

Percentage error (uncertainty)

Answer 21

(number of times used x uncertainty) /
Amount measured

Question 22

Ionic bond

Answer 22

Strong electrostatic attraction between oppositely charged ions held in a lattice

Question 23

Explain how Na and Cl react

Answer 23

Na atom loses its 3s electron, forming Na+ ion
Cl atom gains that electron, forming Cl- ion
Forming NaCl

Question 24

Bp and mp for ionic compounds

Answer 24

High
Because strong electrostatic attraction between oppositely charged ions

Question 25

Can ionic compounds conduct electricity?

Answer 25

Yes when molten or in aq Ions are free to move and carry charge

Question 26

Are ionic compounds soluble in water?

Answer 26

Yes Water molecules break the lattice and surround the ions

Question 27

What is simple covalent bonding?

Answer 27

Strong covalent bonds between atoms and weak VDW between molecules

Question 28

Are there any lone pair in simple covalent bonding?

Answer 28

No - they are all bonded

Question 29

Can simple covalent molecules conduct electricity?

Answer 29

No - no free electron

Question 30

So simple covalent molecules have a high/ low bp and mp?

Answer 30

Low - small amount of energy is needed to break the weak VDW between molecules

Question 31

Example of molecular covalent substances

Answer 31

Crystalline: Water (ice), iodine Chlorine, oxygen

Question 32

Macromolecules

Answer 32

-high mp and bp: breaking lots of strong covalent bond - don’t conduct electricity (except graphite)

Question 33

Example of macromolecules

Answer 33

Diamond, Graphite

Question 34

Properties of diamond

Answer 34

Hard- each C atom is bonded with 4 others (strong covalent bond) High mp Tetrahedral 109.5 Can’t conduct electricity

Question 35

Properties of graphite

Answer 35

Each C atom is bonded with 3 others VDW between Layers - slide over High mp Hexagonal 120 Conduct electricity - delocalised electron

Question 36

Coordinate bond

Answer 36

Share two electrons from the same atom

Question 37

Example of coordinate bond

Answer 37

NH4+ , H3O+, BF4-

Question 38

Electronegativity

Answer 38

The ability to attract an electron in a covalent bond

Question 39

Electronegativity ______ across the period

Answer 39

Increases - the atomic radius decreases, so stronger attraction between the nucleus and electrons

Question 40

Electronegativity _____ decreases down the group

Answer 40

Decreases - the atomic radius increases as there are more shielding, so the attraction between the nucleus and the electrons in the covalent bond decreases

Question 41

Example of non - polar covalent bond

Answer 41

Cl-Cl H-H C-H

Question 42

Example of polar covalent bond

Answer 42

H-Cl C-Cl Be-Cl

Question 43

Why B-F is polar but BF3 is non - polar?

Answer 43

Because the shape is trigonal planar (symmetrical) , the polarities of the bond cancel each other out

Question 44

What other shape is non polar?

Answer 44

Linear, tetrahedral, octahedral

Question 45

Induced dipole - dipole forces (VDW)

Answer 45

Larger atoms More electrons Greater VDW between atoms

Question 46

Permanent d-d forces

Answer 46

Polar molecules Stronger than VDW

Question 47

Hydrogen bond

Answer 47

H atom and the lone pair of O/N/F Strongest intermolecular forces

Question 48

Hess’s law

Answer 48

The enthalpy change for a chemical reaction is independent of the route taken

Question 49

Mean bond enthalpy

Answer 49

The measure of energy required to break one mole of a covalent bond In the gaseous state