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A level Chemistry 2 > The Periodic Table > Flashcards

The Periodic Table Flashcards

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1
Q

Define a group of the periodic table

A

A vertical column in the periodic table. Elements in a group have similar chemical properties. And their atoms have the same number of electrons in their outer shell.

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2
Q

Define a period of the periodic table

A

A horizontal row in the periodic table. Elements show trends in properties across a period.

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3
Q

What is periodicity

A

The regular repeating pattern in properties of the elements across different periods.

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4
Q

How is a subshell different to an orbital

A

A sub shell is a group of the same type of orbitals e.g p-orbitals
Orbitals are regions within an atoms that contain up o 2 electrons.

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5
Q

Explain why the 1st ionisation energy decreases between Be and B

A
  1. Between groups 2 and 3 the p subshell begins to fill.
  2. In Be the outer electron is in the 2s orbital.
  3. In B the outer electron is in a 2p orbital
  4. The 2p orbital in B is of higher energy and experiences more shielding from inner electrons.
  5. Despite the fact that the nuclear charge increases by +1 from Be to B,
  6. The difference in shielding and energy means the nuclear attraction is weaker in B, so less energy is required to remove it’s outer electron.
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6
Q

Why do group 4 elements have the highest melting points fro periods 2 and 3

A

Because carbon and silicon form giant covalent structure - bonding to 4 other atoms- this requires a lot of energy to break. Boron only has 3 covalent bonds so has a lower melting points.

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7
Q

Describe the trend in atomic radii across a period

A
  1. The atomic radius decreases
  2. As you go across a period there is a very little increase in electrons shielding
  3. However there is a regular increase in nuclear charge +1
  4. The overall effect is that the outer electrons are pulled more strongly towards the nucleus as you go across a period.
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8
Q

Write reactions of group 2 metals with oxygen, water and acid

A

Metal (s) + Oxygen (g) –> Metal Oxide (s)
Metal (s) + Water (l) –> Metal Hydroxide (aq) + Hydrogen (g)
Metal (s) + Acid (aq) –> Salt (aq) + Hydrogen (g)

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9
Q

Write electron half equations for the reaction of group 2 metal and Oxygen

A

M –> M2+ + 2e-

O + 2e- –> O2-

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10
Q

Write balanced symbol equations for barium with ethanoic acid

A

Ba (s) +2CH3COOH (aq) –> Ba(CH2COO)2 (aq) + H2 (g)

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11
Q

What figures should you look at when linking ionisation energy and reactivity with water in group 2 metals

A

The sum of the 1st and 2nd ionisation energies
Group 2 metals form 2+ ions so two electrons must be removed. The energy required to do this is the sum of the 1st and 2nd IE.

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12
Q

Suggest why ionisation energy will not be the only factor that affects reactivity of the metal towards water

A

IE suggests the metal is a gas which isn’t the natural states of a lot of metals.

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13
Q

Describe the trend in reactivity as you go down group 2

A

The reactivity increases as you go down the group as IE decreases.

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14
Q

Write equation of a group 2 metal oxide with water.

And write observations

A

MO (s) + H2O (l) –> M(OH)2 (aq)

First the metal oxide would dissolve and then a cloudy white solution would form.

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15
Q

Define solubility

A

A measure of the ability of a solute to dissolve in a solvent. (moldm-3)

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16
Q

Define alkali

A

A type of base that dissolves in water forming hydroxide ions.

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17
Q

Define alkaline

A

A term used to describe a solution containing hyroxide ions.

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18
Q

Define alkalinity

A

A measure of the concentration of hydroxide ions present in an alkaline solution (moldm-3)

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19
Q

Define pH

A

A measure of the concentration of hydrogen ions present in a solution.

20
Q

Describe increase in pH of group 2 metal hydroxides as you go down the group.

A

As you go down the group the solubility of the metal hydroxides increases.
This means there will be more OH- ions in the solution.
This makes it more alkaline so increases the pH.

21
Q

Describe chlorine- state, colour and hazards at R.T

A

Gas, Green and Toxic

22
Q

Describe bromine- state, colour and hazards at R.T

A

Liquid, brown (orange vapour), toxic and corrosive

23
Q

Describe iodine- state, colour and hazards at R.T

A

Solid, grey, toxic vapour formed when heated

24
Q

What is trend in boiling point as you go down group 7

A

Boiling point increases so reactivity decreases

25
Q

What affects the boiling points of halogens

A

London forces- so number of electrons

26
Q

In which halogen molecule, Cl2, Br2 or I2, is the covalent bond strongest and why

A

Cl2
Because the covalent bond is formed by a pair of electrons between the atoms attracting the nuclei of these atoms. The close the electrons are to the nucleus the stronger the attraction.

27
Q

Write colours of chlorine, bromine and iodine in water and in cyclohexane

A 
Chlorine
1. water- very pale green (colourless)
2. cyclohexane- pale green (colourless)
Bromine
1. water- orange
2. cyclohexane- orange
Iodine
1. water- brown
2. cyclohexane- violet
28
Q

What is the colours of the halogen ions

A

colourless

29
Q

Why do two layers from when an organic solvent is added to a solution containing halogens

A
  1. Because the two layers are immiscible
  2. Hexane is non-polar - only forms London forces between molecules
  3. But water forms hydrogen bonds
30
Q

Write chemical equation for reaction between chlorine solution and potassium bromide

A

Cl2(aq) + 2KBr(aq) –> Br2(aq) + 2KCl(aq)

31
Q

Which layer of the 2 layers formed when an organic solvent to halogens is organic

A

The top layer- it is less dense

32
Q

Define disproportionation

A

The oxidation and reduction of the same element in a redox reaction

33
Q

Write equation for the reaction of chlorine with water

A

Chlorine + water –> chloric (I) acid + hydrochloric acid

Cl2(g) + H2O(l) –> HClO(aq) + HCl(aq)

34
Q

Why is chlorine added to drinking water

A

To kill bacteria

35
Q

What affects the reactivity of halogens

A

The decreasing ease of forming 1- ions - IE energy

36
Q

What are risks of adding chlorine to water

A

Chlorine can react with hydrocarbons producing products which are suspected carcinogens

37
Q

Write reaction of Chlorine with sodium hydroxide

A

Chlorine + sodium hydroxide –> sodium chlorate (I) + sodium chloride + water
Cl2(g) + 2NaOH(aq) → NaClO(aq) + NaCl (aq) + H2O(l)

38
Q

Why is sodium chlorate (I) more effective as a bleach than chloric (I) acid

A

It doesn’t decompose as readily so lasts longer

39
Q

What happens to the pH of group 2 metal hydorxides as you go down the group

A 
It increases
Mg- 10
Ca- 11
Sr- 12
Ba- 13
40
Q

Describe the trend in solubility of the group 2 metal hydroxides as you go down the group

A

The solubility increases

41
Q

How is the solubility of the metal hydroxides related to the alkalinity

A

More soluble means more oh- ions present so more alkaline

42
Q

What is the most common type of reaction with a group 2 metal

A

Redox reaction:

Each metal atom is oxidised losing 2 electrons

43
Q

Show redox reaction with Mg and oxygen

A

2Mg(s) + O2 (g) → 2MgO (s)

  1. Each Mg loses two electrons - oxidised
  2. Each O gains two electrons - reduced
44
Q

Show redox reaction with Sr and water

A

Sr (s) + 2H2O (l) →Sr(OH)2 (aq) + H2 (g)

  1. Each Sr loses two electrons- oxidised
  2. Two of the H decrease by 1 oxidation number forming H2
  3. Two H don’t change forming Sr(OH)2
45
Q

Show redox reaction woth HCl and Mg

A

Mg (s) + 2HCl (aq) →MgCl2 (aq) + H2 (g)

  1. Each Mg loses two electrons - oxidised
  2. Each H decreases oxidaiton number by 1- reduced
46
Q

Give an example of how group 2 compounds can be used in agriculture

A
  1. They are basic so can neutralise acids
  2. Calcium hydroxide is added to fields
  3. It neutralise acid in soil to form water
    Ca(OH)2 (s) + 2H+ (aq) → Ca2+ (aq) + 2H2O (l)
47
Q

Give an example of how group 2 compounds can be used in medicine

A
  1. They are used as antacid for treating acid indigestion
  2. They neutralise the acid in your stomach- CaCO3 (s) and Mg(OH)2 (s)
    Mg(OH)2 (s) + 2HCl (aq) → MgCl2 (aq) + 2H2O(l)
    CaCO3 (s) +2HCl → CaCl2 (aq) + H2O (l) + CO2 (g)

A level Chemistry 2 (22 decks)

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