Elements of Life

Question 1

What are isotopes

Answer 1

Atoms of the same element with a different number of neutrons in the nucleus

Question 2

Relative Atomic Mass = ?

Answer 2

(Relative isotopic mass x Relative abundance)/100

Question 3

Speed of light in a vacuum

Answer 3

3x10^8 m/s

Question 4

Wavespeed = ?

Answer 4

Wavelength x Frequency

Question 5

Energy of a photon = ?

Answer 5

Planck constant x Frequency

Question 6

Flame colours of lithium, sodium, potassium, calcium, barium, and copper

Answer 6

Li+ -- Bright red
Na+ -- Yellow
K+ -- Lilac
Ca2+ -- Brick red
Ba2+ -- Apple green
Cu2+ -- Blue green

Question 7

The four main points of Bohr’s theory

Answer 7

• Electrons only exist in certain definite energy levels or electron shells
• A photon of light is emitted when electrons change from one energy level to another
• The energy of the photon is equal to the different between the two energy levels
• E = hv

Question 8

How many electrons can an orbital hold and how many orbitals per subshell

Answer 8

Each orbital can hold two electrons

• 1 orbital in s sub-shell
• 3 orbitals in p sub-shell
• 5 orbitals in d sub-shell
• 7 orbitals in f sub-shell

Question 9

Which elements have a strange electronic structure?

Answer 9

Copper and chromium. The 4s orbital contains only one electron rather than two

Question 10

Melting and boiling points across period 3

Answer 10

Both melting and boiling points initially increase but fall dramatically after silicon. This means the bonds in phosphorous must be weaker and easier to overcome than those between silicon

Question 11

Covalent bonding

Answer 11

A bond in which electrons are shared between atoms

Question 12

Four points needed to answer a shape and bond angle question

Answer 12

• The shape and the bond angle
• The number of areas of electron density
• Electrons repel to get as far away as possible
• Lone pairs repel more than bond pairs

Question 13

2 x bond pairs

Answer 13

180 degrees, linear

Question 14

3 x bond pairs

Answer 14

120 degrees, trigonal planar

Question 15

4 x bond pairs

Answer 15

109.5 degrees, tetrahedral

Question 16

2 x bond pairs, 1 x lone pair

Answer 16

107 degrees, bent

Question 17

2 x bond pairs, 2 x lone pairs

Answer 17

104.5 degrees, bent

Question 18

3 x bond pairs, 1 x lone pair

Answer 18

107 degrees, trigonal pyramidal

Question 19

5 x bond pairs

Answer 19

120 degrees and 90 degrees, trigonal bipyramidal

Question 20

4 x bond pairs, 2 lone pairs

Answer 20

90 degrees, square planar

Question 21

Moles = ?

Answer 21

Mass (g) / Relative Formula Mass (g/mol)

Concentration (mol/dm3) x Volume (dm3) x 1000

Question 22

Water of crystallisation

Answer 22

The crystals of some ionic lattices include molecules of water. To remove, heat the substance to a constant mass

Question 23

Percentage yield = ?

Answer 23

(Experimental yield / Theoretical yield) x 100

Question 24

Factors which reduce the amount of product produced

Answer 24

• Loss of products from reaction vessels
• Side reactions occurring, producing unwanted by-products
• Impurities in the reactants
• Changes in temperature and pressure
• If the reaction is an equilibrium system

Question 25

Acid + alkali --> Acid + base --> Acid + carbonate --> Acid + metal -->

Answer 25

Salt + water Salt + water Salt + water + carbon dioxide Salt + hydrogen

Question 26

Test for Cu2+

Answer 26

Add sodium hydroxide, if present then blue precipitate will form

Question 27

Test for Fe2+

Answer 27

Add sodium hydroxide, if present then 'dirty' green precipitate will form

Question 28

Test for Fe3+

Answer 28

Add sodium hydroxide, if present then orange/brown precipitate will form

Question 29

Test for Pb2+

Answer 29

Add potassium iodide, if present then bright yellow precipitate will form

Question 30

Test for Cl-

Answer 30

Add silver nitrate, if present then white precipitate will form

Question 31

Test for Br-

Answer 31

Add silver nitrate, if present then cream precipitate will form

Question 32

Test for I-

Answer 32

Add silver nitrate, if present then yellow precipitate will form

Question 33

Test for SO4 2-

Answer 33

Add barium chloride, if present then white precipitate will form

Question 34

Ionic bonding. Melting and boiling point, hardness, electrical conductivity, and solubility

Answer 34

- Occurs between a metal and a non-metal - Typically have high melting and boiling points - Typically hard - Will conduct when molten and dissolved - Often soluble in water - Insoluble in non-polar solvents

Question 35

Giant covalent lattice. Melting and boiling points, hardness, electrical conductivity, and solubility

Answer 35

- Occurs between two non-metals - Very high melting and boiling points - Very hard (except for graphite) - Do not conduct (except graphite) - Insoluble in water - Insoluble in non-polar solvents

Question 36

Metallic bonding. Melting and boiling points, hardness, electrical conductivity, and solubility

Answer 36

- Occurs between metals - Generally high melting and boiling points (except mercury) - Conducts when solid or liquid - Insoluble in water - Insoluble in non-polar

Question 37

Simple covalent bonding. Melting and boiling points, hardness, electrical conductivity, and solubility

Answer 37

- Low melting and boiling points - Soft - Do not conduct - Usually insoluble in water unless they contain groups which can hydrogen bond - Usually soluble in non-polar solvents

Question 38

First ionisation enthalpy

Answer 38

The energy needed to remove one electron from every atom in one mole of isolated gaseous atoms of the element

Question 39

Trend in ionisation enthalpy

Answer 39

- Ionisation enthalpy increases across a period - Nuclear charge increases across a period which holds the electrons with a stronger force - Smaller atomic radii across the period which means electrons are closer to the nucleus - Electron shielding would decrease the ionisation enthalpy but not enough to counteract the nuclear charge and atomic radii

Question 40

Group 2 reaction with oxygen

Answer 40

Assuming M is the group two element 2M + O2 --> 2MO

Question 41

Group 2 reactions with carbonates

Answer 41

Assuming M is the group two element MCO3 --> MO + CO2

Question 42

Explain the trend in thermal stability down the group 2 carbonates

Answer 42

The thermal stability of the group two carbonates increases down the group as the charge density of the cations increases meaning they can polarise the negative charge cloud around the carbonate ion making it less stable and easier to break down

Question 43

Trends down group 2

Answer 43

- Increasing reactivity - Increasing thermal stability - Increasing pH of hydroxide - Increasing solubility of hydroxide - Decreasing solubility of carbonates

Question 44

Concentration = ?

Answer 44

(1000 x Moles)/Volume