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AQA A Level Chemistry > 2.2 Group 2, The Alkaline Earth Metals > Flashcards

2.2 Group 2, The Alkaline Earth Metals Flashcards

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1
Q

Group 2 elements lose __ electrons when they react

A

2

(all end s2 & make 2+ ions)

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2
Q

Atomic Radius _____ Down the Group

A

Increases

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3
Q

Why does atomic radius increase down the group? (3)

A
  • Number of shells increase
    • More distance between nucleus and outer electrons
  • Outer shells more shielded
  • Less attraction between nucleus and outer electrons
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4
Q

First Ionisation Energy ______ Down the Group

A

Decreases

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5
Q

Explain why first ionisation energy decreases down the group (4)

A
  • Number of shells increase
    • Increased distance between nucleus and outer electrons
  • Outer shells more shielded
  • Less attraction between nucleus and outer electrons
  • Easier to remove outer electron = less energy
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6
Q

Reactivity ______ Down the Group

A

Increases

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7
Q

Explain why reactivity increases down the group

A
  1. First ionisation energy decreases down group
    • Due to increasing atomic radius and shielding effect
  2. When Group 2 elements react = lose electrons & form positive ions
    • Easier it is to lose electrons (i.e. the lower the 1st and 2nd ionisation energies) = more reactive the element
    • So reactivity increases down group
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8
Q

Melting Points _______ _______ Down the Group

A

Generally Decrease

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9
Q

Describe Group 2 elements’ structure

A
  • Metallic structures
    • Positive ions in crystal structure surround by delocalised electrons from outer electron shells
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10
Q

Why do melting points generally decrease down the group? (4)

A
  • Size of positive ion increases, but charge remains the same
  • Delocalised electrons further away from positive ions
  • Weaker electrostatic forces of attraction between positive ions and delocalised electrons
  • Weaker metallic bonds = less energy needed to break
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11
Q

Where is there a big ‘blip’ at magnesium?

A

∵ crystal structure (arrangement of metallic ions) changes

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12
Q

Group 2 Elements React with ____

A

Water

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13
Q

When they react with water, they are oxidised from start of ____ to ____ forming ____ ____

A

When they react with water, they are oxidised from start of 0 to +2 forming M2+ ions

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14
Q

When Group 2 metal react with water, what 2 products do they give?

A

Metal hydroxide and hydrogen

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15
Q

Group 2 Elements React with Water

State the general symbol equation

A
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16
Q

Group 2 metals react ___ _____ down the group

A

more readily

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17
Q

Why do Group 2 metals react more readily down the group?

A

∵ ionisation energies decrease

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18
Q

Solubility Trends depend on ______ ___

A

Compound Anion

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19
Q

State the 2 general solubility trends of Group 2 elements

A
  1. Generally, compounds of Group 2 elements that contain singly charged negative ions (e.g. OH-) ↑ in solubility down group
  2. Compounds that contain doubly charged negative ions (e.g. SO4-2) ↓ in solubility down group
20
Q

Fill in the gaps

A
21
Q

What are compounds like magnesium hydroxide, which have very low solubilities said to be?

A

Sparingly soluble

22
Q

Barium sulfate is _____ in water

A

insoluble

23
Q

Describe the test for sulfate ions (SO42-)

A
  1. Add dilute hydrochloric acid and then barium chloride solution, BaCl2(aq)
  2. If white precipitate of barium sulfate forms = original compound contained sulfate
24
Q

Test for sulfate ions

Why should you acidify the solution?

A

To get rid of any lurking sulfites or carbonates which will also produce a white precipitate

25
Q

What are Group 2 compounds used for?

A

To neutralise acidity

26
Q

Name 2 common examples of Group 2 compounds that are used to neutralise acidity

A
  • Calcium hydroxide (slaked lime, Ca(OH)2)
  • Magnesium hydroxide (Mg(OH)2)
27
Q

What is calcium hydroxide used for?

A

In agriculture to neutralise acidic soils

28
Q

What is magnesium hydroxide used for?

A
  • Used in indigestion tablets as an antacid
  • Substance which neutralises excess stomach acid
29
Q

State the ionic equation for neutralisation, include the state symbols

(for both Ca(OH)2 & Mg(OH)2)

A

H+(aq) + OH-(aq) → H2O(l)

30
Q

What is barium sulfate is used in?

A

‘Barium Meals’

31
Q

Barium sulfate is ______ to X-rays

A

Barium sulfate is opaque to X-rays - won’t pass though it

32
Q

What are ‘barium meals’ used to help?

A

Diagnose problems with oesophagus, stomach or intestines

33
Q

Describe how ‘barium meals’ are used

A
  1. Patient swallows barium meal
  2. Barium sulfate coats tissues, making them show up on X-rays, showing structure of organs
34
Q

What is magnesium used for?

A

To extract titanium from its ore

35
Q

Describe how magnesium is used to extract titanium from its ore

A
  1. Main titanium ore (TiO2) is converted to titanium(IV) chloride (TiCl4) by heating it with carbon in steam of chlorine gas
  2. Titanium chloride is then purified by fractional distillation
  3. Then reduced by magnesium in furnace at 1000°C
36
Q

Represent how magnesium is used to extract titanium from its ore by writing an equation

A
37
Q

What is wet scrubbing?

A

When acidic sulfur dioxide is removed from flue gases by reacting with an alkali

38
Q

Name 2 substances that can be used to remove sulfur dioxide from flue gases

A

Powdered calcium oxide (CaO, lime) and calcium carbonate (CaCO3, limestone)

39
Q

Describe how calcium oxide and calcium carbonate is used to remove sulfur dioxide from flue gases

A
  1. Slurry is made by mixing calcium oxide or calcium carbonate with water
  2. The sprayed onto flue gases
  3. Sulfur dioxide reacts with alkaline slurry and produces solid waste product, calcium sulfite
40
Q

Represent how calcium oxide is used to remove sulfur dioxide from flue gases by using an equation

A
41
Q

Represent how calcium carbonate is used to remove sulfur dioxide from flue gases by using an equation

A
42
Q

Explain why it’s possible to use barium sulfate in barium meals even though barium ions are poisonous

A

Barium sulfate is insoluble ∴ non-toxic

43
Q

Explain why the electronegativity values of Group 2 elements Be-Ba decrease down the group (2)

A
  • Increases in no. of shells/increased sheilding
  • Decreased attraction for bonding electrons
44
Q

Write the ionic equation, with state symbols, to show the reaction of calcium with an excess of water

A

Ca(s) + H2O(l) → Ca2+(aq) + 2OH-(aq) + H2(g)

45
Q

Magnesium reacts rapidly with ___

A

steam

46
Q

State two observations made when magnesium reacts with steam (2)

A
  • White light
  • White powder
47
Q

Write the equation for when magnesium reacts with steam

A

Mg + H2O → MgO + H2

AQA A Level Chemistry (36 decks)

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