atomic structure

Question 1

relative atomic mass

Answer 1

weighted mean mass of an atom compared with 1/12th mass of carbon-12

Question 2

atomic number

Answer 2

no of protons

Question 3

mass number

Answer 3

no of protons and neutrons

Question 4

differences between isotopes

Answer 4

different number of neutrons
different mass numbers
different PHYSICAL properties

Question 5

why do different isotopes of an element have the same chemical properties

Answer 5

same electronic confirguration/ same number of electrons in outer shell

Question 6

relative isotopic mass

Answer 6

mass of an atom of an isotope compared with 1/12th mass of carbon-12

Question 7

When is relative molecular mass used

Answer 7

For simple molecules

Question 8

When is the term relative formula mass used

Answer 8

For compounds with giant structures

Question 9

Describe what would happen when carbonate reacts with excess dilute hydrochloric acid

Answer 9

Effervescence and solid would dissolve

Question 10

When doing water of crystallisation, why repeat four readings ?

Answer 10

To make sure all the water has been removed

Question 11

Suggest 2 modifications to water that would reduce percentage uncertainty in mass of residue (water crystallisation)

Answer 11

Use balance that weighs to 3 decimal places
Use a larger mass

Question 12

How could student obtain a sample of magnesium phosphate after reacting magnesium with phosphoric acid

Answer 12

Filter to obtain solid/precipitate
Dry solid
Evaporate water

Question 13

Molecular formula meaning

Answer 13

Number of atoms of each element present in a molecule

Question 14

Why is there a loss in mass in carbonate equations

Answer 14

CO2 lost/produced as gas

Question 15

Describe and explain change in rate of reaction

Answer 15

Rate of reaction decreases and concentration decreases
Less frequent collisions

Question 16

Method to do mass change experiment

Answer 16

Beaker
Balance
Stopwatch
Record mass at time intervals

Question 17

When reacting group 2 metal with water, if metal is further down the group, would volume produced of hydrogen change?

Answer 17

Less volume
Fewer moles of metal reacting

Question 18

Why is atom economy 100%

Answer 18

Only one product
No waste products
Addition reaction

Question 19

Why is atom Economy not 100%

Answer 19

Two products
Waste product
Substitution reaction

Question 20

Empirical formula meaning

Answer 20

Simplest whole number ratio of atoms present in a compound

Question 21

Two improvements for gas volume heat experiment

Answer 21

Heat until syringe stops moving/no further gas produced
Wait until gas has cooled before measuring volume

Question 22

How to make sure all water has been removed

Answer 22

Heat to constant mass

Question 23

Disadvantage of using chlorine for purification of drinking water

Answer 23

Chlorine is toxic
Forms carcinogens

Question 24

Describe the relative energies of 2s orbital and each of the 2p orbitals

Answer 24

P orbitals have greater energy than s orbitals
P orbitals have equal energy

Question 25

How to reduce atom economy

Answer 25

Use metal with lower molar mass

Question 26

How many orbitals in s

Answer 26

1

Question 27

How many orbitals in p

Answer 27

3

Question 28

How many orbitals in d

Answer 28

5

Question 29

How many orbitals in f

Answer 29

7

Question 30

First four members of alkanes are all gases but first four alcohols are all liquids. Explain this difference in terms of intermolecular forces

Answer 30

Alcohols have hydrogen bonds Hydrogen bonds are stronger than Van der Waals’ forces in alkanes

Question 31

Explain the bond angle

Answer 31

Electron pairs repel Bonded pairs repel Lone pairs repel more than bonding pairs

Question 32

Electronegativity meaning

Answer 32

Ability of an atom to attract electrons In a covalent bond

Question 33

Why is this molecule polar

Answer 33

Dipoles don’t cancel out Molecule is non symmetrical Bonds are polar Difference in electronegativities

Question 34

Definition of term ionic lattice

Answer 34

Repeating pattern of oppositely charged ions

Question 35

Explain two anomalous properties of ice caused by hydrogen bonding

Answer 35

Ice is less dense than water - molecules in ice are held apart by hydrogen bonds Relatively high melting point - more energy needed to overcome strong hydrogen bonds

Question 36

Observation when adding metal to water

Answer 36

Effervescence and solid dissolved

Question 37

Why student uses large excess of alcohol in experiment

Answer 37

To keep its concentration constant