Group 2 Flashcards by Lucy Williams

How many valence electrons do the elements in group 2 have?

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How do Group 2 metals form ionic compounds?

Donate two outermost electrons
Become +2 ion
Act as reducing agents

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What trend is seen in reactivity going down group 2?

Metals become more reactive

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What is meant by first ionisation energy?

The energy needed to remove the first outer electron of an atom

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What is meant by second ionisation energy?

The energy needed to remove the second outer electron of an atom

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Why do the first and second ionisation energies decrease down group 2?

Increased shielding
Larger distance between outermost electrons and nucleus
Outweigh higher nuclear charge

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Why does reactivity increase down group 2?

Easier for atoms to lose electrons

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How is dilute hydrochloric used to show increasing reactivity of group 2 metals?

Bubbles of hydrogen gas given of much faster indiating reactions become more vigorous

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How is oxygen used to show increasing reactivity of group 2 metals?

Metals get more reactive with oxygen going down group
Ba is stored in oil to prevent reaction with air

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What trend is seen in atomic radius down group 2 metals?

Increases

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Why does atomic radius increase down group 2?

Addition of another principal quantum shell

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What trend is seen in melting points down group 2 metals?

Decreases

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Why does melting point decrease down group 2?

Outer electrons get further from nucleus
Attraction between nucleus and bonding electrons decreases

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What trend is seen in density down group 2 metals?

Drops then increases

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How does pH of the solution formed from reaction of group 2 oxides with water change down group?

Become more alkaline

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Why does solution formed become more alkaline down group 2?

Due to solubility of group 2 hydroxides

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What is the equation for metal X hydroxide dissolving in water?

X(OH)₂ (aq) → X₂+ (aq) + 2OH- (aq)

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What trend is seen in the solubility of group 2 sulfates down group 2?

Decreases

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How does magnesium react with oxygen?

Burns easily
Bright white light

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How does magnesium react with water?

Vigorous reaction with steam
No reaction with water

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How does magnesium react with dilute HCl?

Reacts vigorously

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How does magnesium react with dilute H₂SO₄?

Reacts vigorously

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How does calcium react with oxygen?

Difficult to ignite
Red flame

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How does calcium react with water?

Reacts moderately
Forms hydroxide

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How does calcium react with dilute HCl?

Reacts vigorously

How does calcium react with dilute H₂SO₄?

Reaction slowed by formation of soluble sulfate layer on metal Stops hydrogen bubbles from rising

How does strontium react with dilute oxygen?

Difficult to ignite Red flame

How does strontium react with water?

Reacts rapidly Forms hydroxide

How does strontium react with dilute HCl?

Reacts vigorously

How does strontium react with dilute H₂SO₄?

Reaction quickly stopped by formation of insoluble sulfate layer on metal

How does barium react with oxygen?

Difficult to ignite Green flame

How does barium react with water?

Reacts rapidly Forms hydroxide

How does barium react with dilute HCl?

Reacts vigorously

How does barium react with dilute H₂SO₄?

Reaction quickly stopped by formation of insoluble sulfate layer on metal

What is the equation for the reaction between magnesium and steam?

Mg(s) + H₂O(g) → MgO(s) + H₂(g)

What is the general equation for the reaction between group 2 metals and water?

M(s) + 2H₂O(l) → M(OH)₂(s) + H₂(g)

Describe the reaction between magnesium and cold water.

Extremely slow Forms weakly alkaline solution as magnesium hydroxide is only slightly soluble

How do group 2 metals react with dilute acid?

Form colourless solutions of metal salts

What is the general equation for the reaction between group 2 metals and dilute HCl?

M(s) + 2HCl(aq) → MCl₂(aq) + H₂(g)

What is the general equation for the reaction between group 2 metals and dilute H₂SO₄?

M(s) + H₂SO₄(aq) → MSO₄(aq) + H₂(g)

Which of the group 2 sulfates are insoluble?

SrSO₄ and BaSO₄

What is different about BeO?

Amphoteric

What does amphoteric mean?

Can act as both acid and base

What does oxide + water form?

Hydroxide

What is limewater?

Calcium hydroxide

What is the general equation for reactions between group 2 oxides and water?

MO(s) + H₂O(l) → M(OH)₂(s/aq)

Which group 2 oxides produce a solid hydroxide?

MgO and CaO

What observation is there for the reaction between magnesium oxide and water?

MgO is only slightly soluble in water Weakly alkaline solution formed

What observation is there for the reaction between calcium oxide and water?

Vigorous reaction - releases lots of energy Some water boils off as solid lump seems to expand and open

What happens when group 2 oxides react with sulfuric acid?

Insoluble sulfates form at surface of oxide Solid oxide beneath can't react with acid Prevented by using powder form and stirring

What does metal oxide + dilute HCl form?

metal chloride + water

What does metal oxide + dilute sulfuric acid form?

metal sulfate + water

What do group 2 metal hydroxides form when reacting with dilute acid?

Colourless solutions of metal salts

What does hydroxide + dilute HCl form?

chloride + water

What does hydroxide + dilute sulfuric acid form?

sulfate + water

What is the general equation for the reaction between a group 2 hydroxide and dilute HCl?

M(OH)₂(s) + 2HCl(aq) → MCl₂(aq) + 2H₂O(l)

What is the general equation for the reaction between a group 2 hydroxide and dilute H₂SO₄?

M(OH)₂(s) + H₂SO₄(aq) → MSO₄(aq) + 2H₂O(l)

Which group 2 carbonates are insoluble in water?

All except BeCO₃

What is different about Ca, Sr and Ba carbonates?

Insoluble sulfate layer on solid carbonates stops further reaction after bubbling of CO₂ gas

What does carbonate + dilute hydrochloric acid form?

chloride + water + carbon dioxide

What does carbonate + dilute sulfuric acid form?

sulfate + water + carbon dioxide

What is the general equation for the reaction between group 2 carbonates and dilute HCl?

MCO₃(s) + 2HCl(aq) → MCl₂(aq) + H₂O(l) + CO₂(g)

What is the general equation for the reaction between group 2 carbonates and dilute H₂SO₄?

MCO₃(s) + H₂SO₄(aq) → MSO₄(aq) + H₂O(l) + CO₂(g)

What three calcium compounds are commonly used in agriculture and construction?

Limestone Quicklime Slaked lime

What is limestone?

Impure calcium carbonate

What is quicklime?

Calcium oxide

What is slaked lime?

Calcium hydroxide

Why are calcium compounds used in agriculture?

To raise pH of soil

How do calcium compounds raise soil pH?

All bases so react with acids in soil to raise pH

What is sulfur scrubbing?

Process of removing sulfur dioxide from flue gases using calcium compounds

What is barium used for?

Used in sulfate form for patients having X-rays on intestines

How does Barium allow intestinal X-rays?

Absorbs X-rays Gut shows up white

Why is barium used in medicine in sulfate form?

Barium is toxic Barium sulfate is insoluble so not absorbed into blood

What is magnesium hydroxide used for?

Treating constipation Used in suspension to neutralise excess stomach acid