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UACE Chemistry > Group IV Elements > Flashcards

Group IV Elements Flashcards

1
Q

Metallic, nonmetallic or metalloid?
- carbon
- Silicon
- Germanium
- Tin
- Lead

A
  • carbon-non-metallic
  • Silicon-metalloid
  • Germanium-metalloid
  • Tin-metal
  • Lead- metal
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2
Q

What type of bonding do the following exhibit?
- carbon
- Silicon
- Germanium
- Tin
- Lead

A
  • carbon -covalent
  • Silicon- covalent
  • Germanium- covalent
  • Tin- metallic
  • Lead- metallic
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3
Q

What is the structure of the following?
- carbon
- Silicon
- Germanium
- Tin
- Lead

A
  • carbon -giant molecular
  • Silicon- giant molecular
  • Germanium- giant molecular
  • Tin- giant metallic
  • Lead- giant metallic
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4
Q

What is the metallic character of group IV?

A
  • C is a non-metal
  • Si and Ge are metalloids
  • Sn and Pb show typical metallic characteristics.
  • The metallic character increases down the group.
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5
Q

Describe the oxidation states of group IV elements

A
  • Group IV elements exhibit +2 and +4 oxidation states in their compounds.
  • The stability of the +2 oxidation state increases down the group due to phenomenon known as inert pair effect.
  • Inert pair effect is caused by the reluctance of s-electrons to participate in bonding.
  • In large atoms such as germanium, tin and lead the s-electrons are not effectively shielded by the d-electrons and as a result the s-electrons become more strongly attracted by the nucleus.
  • Hence the increase in the inert pair effect down the group.
  • Consequently the +4 oxidation state becomes less stable down the group.
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6
Q

What makes carbon unique?

A
  • Carbon has the smallest atomic radius
    • Carbon has the highest electronegativity
    • Carbon lacks vacant d-orbital electrons.
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7
Q

What is catenation?

A

Catenation is the ability of atoms of the same element to bond to each other forming stable long chain and ring compounds.

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8
Q

How does carbon differ from the rest of group IV elements?

A
  • Carbon can form long stable chains of carbon atoms and ring compounds i.e. catenation.
    (Carbon is capable of catenation because of the high carbon-carbon bond energy resulting into stable compounds.)
  • Carbon can form multiple bonds with itself and other elements
  • Carbon forms a maximum of four covalent bonds while other group members can form up six covalent bonds.
  • Carbon forms gaseous oxides; other group members form solid oxides.
  • Carbon tetrahalides are not hydrolysed by water unlike tetrahalides of other group members.
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9
Q

How do group IV elements react with oxygen?

A

They all react with oxygen on heating forming dioxides apart from lead that forms a monoxide

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10
Q

How do group IV elements react with water?

A
  • White hot carbon is oxidized by steam to carbon monoxide and the steam reduced to hydrogen gas.
  • Silicon is oxidized by steam (or boiling water) to silicon(IV) oxide and the water reduced to hydrogen gas
  • Tin reacts with steam forming tin (iv) oxide and hydrogen gas
  • Lead reacts slowly with soft water containing oxygen forming lead(ii) hydroxide
  • Germanium is protected by a thin layer of germanium(iv) oxide and does not react with water in any form
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11
Q

How do group IV elements react with alkalis?

A
  • Carbon is not attacked by sodium hydroxide or any other alkalis
  • Silicon, germanium, tin and lead react with hot, concentrated aqueous sodium hydroxide forming a solution consisting of silicate, germanate(IV), stannate(IV) and plumbate(II) ions respectively and liberating hydrogen gas.
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12
Q

How do group IV elements react with dilute nitric acid?

A
  • All group IV elements do not react with dilute mineral acids except tin that reacts with dilute nitric acid forming a mixture nitrogen compounds.
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13
Q

How is carbon monoxide prepared?

A

CO is a neutral oxide prepared by:
- Reduction of carbon dioxide gas by hot charcoal/coke/carbon

  • Dehydration of methanoic acid by concentrated sulphuric acid
  • Dehydration of ethanedioic acid crystals by concentrated sulphuric acid. The carbon dioxide gas can be removed by passing the gaseous products through concentrated sodium hydroxide solution or concentrated potassium hydroxide solution.
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14
Q

How is silicon(II) oxide prepared?

A

It is very unstable and is prepared by heating silicon(IV) oxide and silicon in oxygen-free conditions.

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15
Q

How is germanium (II) oxide prepared?

A

By reduction by heating germanium(IV) oxide, GeO2 with germanium.

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16
Q

How is tin(II) oxide prepared?

A

By heating tin(II)ethanedioate or tin(II)hydroxide.

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17
Q

How is lead (II) oxide prepared?

A

By heating lead(II) nitrate or lead(II) hydroxide or lead(II) carbonate.

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18
Q

How do group IV monoxides react with acids?

A
  • Carbon monoxide is a neutral oxide and does not react with acids.
  • Germanium(II) oxide, silicon(II) oxide, tin(II) oxide and lead(II) oxide are amphoteric.
  • They react with acids with increasing vigour from GeO to PbO as their basic character increase forming soluble a salt and water.
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19
Q

How do group IV monoxides react with alkalis?

A
  • Carbon monoxide is a neutral oxide and does not react with alkalis.
  • Germanium(II) oxide, tin(II) oxide, and lead(II) oxide are amphoteric.
  • They react with concentrated sodium hydroxide forming soluble complexes of germanate(II), stannate(II) and plumbate(II) ions.
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20
Q

What type of bonding do the following exhibit?
- carbon dioxide
- Silicon(iv) oxide

A
  • carbon dioxide -covalent
  • Silicon(iv) oxide- covalent
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21
Q

What type of structure do the following have?
- carbon dioxide
- Silicon(iv) oxide
- Germanium(iv) oxide
- Tin(iv) oxide
- Lead(iv) oxide

A
  • carbon dioxide -simple molecular
  • Silicon(iv) oxide- giant molecular
  • Germanium(iv) oxide- giant ionic
  • Tin(iv) oxide- giant ionic
  • Lead(iv) oxide- giant ionic
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22
Q

Acidic, basic, or amphoteric?

  • carbon dioxide
  • Silicon(iv) oxide
  • Germanium(iv) oxide
  • Tin(iv) oxide
  • Lead(iv) oxide
A
  • carbon dioxide- acidic
  • Silicon(iv) oxide- acidic
  • Germanium(iv) oxide- amphoteric
  • Tin(iv) oxide- amphoteric
  • Lead(iv) oxide- amphoteric
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23
Q

How is carbon dioxide prepared?

A

Action of dilute hydrochloric acid on calcium carbonate or by burning carbon in excess oxygen

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24
Q

How is silicon(iv) oxide prepared?

A

Heating silicon in oxygen

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25
Q

How is germanium(iv) oxide prepared?

A

Heating germanium in oxygen

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26
Q

How is tin(iv) oxide prepared?

A

Heating tin in oxygen

27
Q

How is lead(iv) oxide prepared?

A

Action of hot dilute nitric acid on tri-lead tetraoxide (also known Lead(II, IV) oxide) or by action of sodium hypochlorite on a soluble lead(II) salt.

28
Q

How is lead(ii, iv) oxide / tri-lead tetraoxide prepared?

A

Lead(II, IV) oxide, Pb3O4 is prepared by heating lead(II) oxide strongly in air to temperatures between 450 – 480 degrees centigrade

29
Q

Describe the bonding and structure of group four dioxides

A
  • carbon dioxide is covalently bonded and has a simple molecular structure consisting of discrete molecules held by weak van der waal forces which are easily broken at low temperature. It is therefore a gas at room temperature.
  • SiO2 is also covalently bonded and has a giant molecular structure consisting of a three – dimension network in which each silicon atom is joined to four oxygen atoms by strong covalent bonds and each oxygen atom bonded to two silicon atoms by single covalent bonds. A lot of heat is needed to overcome or break the many strong covalent bonds and this explains why silicon(IV) oxide is a solid at room temperature with very high melting point.
  • GeO2, SnO2 and PbO2 predominantly ionic. PbO2 is unstable and on little heating decomposes forming lead(II) oxide and oxygen.
30
Q

Describe the action of acids on dioxides of group IV

A
  • CO2 is acidic and does not react with any acid.
  • Silicon(IV) oxide is acid and does not react with other acids, except hydrofluoric acid forming hexafluorosilicic acid and water.
  • GeO2, SnO2 and PbO2 are amphoteric and therefore they react with dilute mineral acids germanium(IV), tin(IV) and lead(IV) salts respectively together with water.
  • PbO2 reacts with cold concentrated hydrochloric acid forming lead(IV) chloride, a colourless liquid and water.
  • (However with warm concentrated hydrochloric acid, a white precipitate of lead(II) chloride, a yellow-green gas (chlorine) and water are formed. This is because lead(IV) chloride is unstable and on warming it decomposes into lead(II) chloride and chlorine gas.)
31
Q

Describe the action of sodium hydroxide on dioxides of group IV

A
  • Carbon dioxide reacts with cold dilute sodium hydroxide forming sodium carbonate and water.
  • Silicon(IV) oxide reacts with hot concentrated sodium hydroxide forming sodium silicate and water.
  • Germanium(IV) oxide, tin(IV) oxide and lead(IV) oxide react with hot concentrated sodium hydroxide forming sodium germannate(IV), sodium stannate(IV) and sodium plumbate(IV) solution respectively and water.
32
Q

True or false
The shape of all group IV tetrachlorides is tetrahedral

A

True

33
Q

True or false
All group IV tetrachlorides have simple molecular structure and covalent bonding

A

True

34
Q

How are group IV tetrachlorides prepared?

A
  • Carbon tetrachloride (tetrachloromethane), CCl4 is a colourless liquid made by reacting carbon disulphide with chlorine in presence iron catalyst.
  • Silicon(IV) chloride, germanium(IV) chloride and tin(IV) chloride are colourless liquids made by heating the elements in a stream of dry chlorine gas.
  • Lead(IV) chloride is a colourless liquid made by reacting lead(IV) oxide with cold concentrated hydrochloric acid.
35
Q

True or false
The thermal stability of the tetrachlorides of group IV decreases from carbon to lead

A

True

  • down the group, the atomic radius of the elements increases, and the M-CL bond becomes longer, and weaker
  • Due to the imert pair effect whereby the s-electrons in the valence shell become more reluctant to take part in bonding. As a result, the +4 oxidation state becomes less stable down the group.
36
Q

True or false
All other group IV tetrachlorides are stable at room temperature but lead tetrachloride is unstable

A

True
It decomposes into lead(ii) chloride and chlorine gas on heating

37
Q

Why does tin tetrachloride have a significantly higher boiling point than carbon tetrachloride?

A

This is due to increased van der waal forces of attraction as the molecular mass of the tetrachlorides increase with increasing atomic mass of the group IV element. The stronger van der waal forces require more heat to break before the individual molecules can separate for boiling to take place.

38
Q

Why isn’t carbon tetrachloride hydrolyzed by water?

A

Due to lack of empty d-orbitals by carbon to accommodate the lone pairs of electrons from water molecules.

39
Q

True or false
SiCl4, GeCl4, SnCl4 and PbCl4 are not hydrolyzed by water molecules

A

False

  • They are hydrolyzed due to presence of empty d-orbitals forming misty fumes of hydrogen chloride.
  • The ease of hydrolysis increases from SiCl4 to PbCl4 as the metallic nature of the element increases. PbCl4 is the most rapidly hydrolysed.
40
Q

True or false
Only Ge, Sn and Pb form stable dichlorides

A

True

They are all ionic solids

41
Q

How is Germanium(II) chloride prepared?

A

By reduction of germanium(IV) chloride vapour by hot germanium.

42
Q

How is Anhydrous tin(II) chloride prepared?

A

By passing dry hydrogen chloride gas over heated tin.

  • SnCl2 is hydrolyzed by water forming a milky suspension consisting of a basic chloride and white fumes of hydrogen chloride.
43
Q

How is PbCl2 is prepared?

A

By precipitation by action of either dilute hydrochloric acid (or aqueous
sodium chloride) on aqueous lead(II) nitrate (or lead(II) ethanoate).

  • PbCl2 is less soluble in water but dissolves in concentrated hydrochloric acid due to formation of a soluble complex of tetrachloroplumbate(II) ions.
44
Q

True of false
Hydrides of group IV elements, are covalent, have simple molecular structures and their molecules have tetrahedral shape

A

True

45
Q

How are group IV hydrides prepared?

A

Prepared by reduction of their tetrachlorides by lithium aluminium hydride (LiAlH4) at 0 degrees centigrade.

46
Q

What is the trend of the thermostability of group IV hydrides?

A

They become less stable down the group because the +4 oxidation state becomes less stable down the group due to inert pair effect.

47
Q

True or false
Carbon tetrahydride is hydrolyzed by water

A

False

It is not hydrolyzed due lack vacant d-orbitals on the carbon atom to accommodate lone pairs of electrons from water molecules.

The rest of the hydrides are hydrolyzed more readily in alkaline, conditions liberating soluble salt and hydrogen gas.

48
Q

What is the result of burning group IV hydrides in air?

A
  • Methane (CH4), Silicon tetrahydride (SiH4) and tin tetrahydrides (SnH4) readily burn in air forming the corresponding dioxide and water.
  • Lead(IV) hydride forms lead(II) oxide and water on burning.
49
Q

What is the result of lead (II) ions reacting with sodium hydroxide?

A

A white precipitate soluble in excess alkali to form a colourless solution.

50
Q

What is the result of lead (II) ions reacting with ammonia solution?

A

A white precipitate insoluble in excess.

51
Q

What is the result of lead (II) ions reacting with dilute hydrochloric acid?

A

A white precipitate soluble on boiling forming a colourless solution and re-precipitates on cooling.

52
Q

What is the result of lead (II) ions reacting with dilute sulphuric acid?

A

A heavy white precipitate insoluble on boiling.

53
Q

What is the result of lead (II) ions reacting with potassium iodide?

A

A yellow precipitate is formed (confirmatory test).

54
Q

What is the result of lead (II) ions reacting with potassium chromate solution?

A

A yellow precipitate is formed.

The precipitate is soluble in dilute nitric acid forming an orange solution.

The precipitate is also soluble in dilute sodium hydroxide forming a yellow solution. (Confirmatory test).

55
Q

What is the result of tin (II) ions reacting with sodium hydroxide solution?

A

A white precipitate soluble in excess alkali to form a colourless solution.

56
Q

What is the result of tin (II) ions reacting with ammonia solution?

A

A white precipitate insoluble in excess

57
Q

What is the result of tin (II) ions reacting with mercury(II) chloride solution?

A

On warming the mixture a white precipitate (mercury (I) chloride) which turns grey.

58
Q

What is the result of tin (II) ions reacting with acidified potassium dichromate(VI) solution?

A

The orange colour of potassium
dichromate(VI) changes to green. This is due to reduction of dichromate(VI) ions to chromium(III) ions by tin(II) ions.

59
Q

What is the result of tin (II) ions reacting with potassium iodide?

A

A yellow precipitate is formed (confirmatory test).

60
Q

What is the result of lead (II) ions reacting with acidified potassium manganate(VII) solution?

A

The purple colour of potassium
manganate(VI) solution changes to colourless. This is due to reduction of manganate(VII) ions to manganese(II) ions by in (II) ions.

61
Q

How do group IV elements react With concentrated nitric acid?

A
  • Silicon does not react with concentrated nitric acid.
  • Carbon, germanium and tin react with concentrated nitric acid forming a dioxide of the element, brown fumes of nitrogen dioxide gas and water.
  • Lead reacts with concentrated nitric acid forming lead(II) nitrate, nitrogen monoxide gas and water
62
Q

How do group IV elements react with concentrated sulphuric acid?

A
  • Carbon reacts with hot concentrated sulphuric acid forming carbon dioxide gas, sulphur dioxide gas and water.
  • Germanium and tin react with hot concentrated sulphuric acid forming germanium(IV) sulphate and tin(IV) sulphate respectively plus sulphur dioxide gas and water.
  • Lead forms lead(II) sulphate, sulphur dioxide and water with hot concentrated sulphuric acid.
63
Q

How do group IV elements react with concentrated hydrochloric acid?

A
  • Carbon, silicon and germanium do not react with concentrated hydrochloric acid.
  • Tin is vigorously reacts with concentrated hydrochloric forming tin(II) chloride and hydrogen gas.
  • Lead reacts with boiling concentrated hydrochloric acid forming lead(II) chloride and hydrogen gas
  • In excess boiling concentrated hydrochloric acid the lead(II) chloride dissolves forming a soluble complex of tetrachloroplumbate(II) ions.
64
Q

How do group IV elements react with concentrated hydrofluoric acid?

A
  • Silicon reacts with hot concentrated hydrofluoric acid forming hexafluorosilicic acid and hydrogen gas.

UACE Chemistry (20 decks)

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