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Z/ HIGHER Chemistry > Unit 1: Chapter 2 - The Periodic Table - Bonding and Structure > Flashcards

Unit 1: Chapter 2 - The Periodic Table - Bonding and Structure Flashcards

1
Q

in metallic bonding what are the atoms arranged in?

A

In metallic bonding the atoms are arranged in a crystalline structure where the positive atoms are surrounded with a SEA OF ELECTRONS.

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2
Q

What is it that holds the structure in place, in metallic bonding?

A

It is the ELECTROSTATIC ATTRACTION of positive atoms and negative outer electrons that hold the structure in place.

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3
Q

What gives the most metals high melting and boiling points and what is the rule for this?

A

The strong electrostatic attraction. The higher the melting point the stronger the electrostatic attraction.

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4
Q

What happens if one electron (electricity) is inserted into one end of a metal and what does this mean for the metal?

A

An electron is ejected at the other end similar to falling dominoes. It can conduct electricity

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5
Q

Why can metals be bent and what is this property called?

A

As the atoms are all the same size, and in an ordered structure, metals can be bent, a property known as malleability.

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6
Q

What is covalent bonding?

A

Covalent bonding is when atoms share pairs of electrons. The covalent bond is a result of two
positive nuclei being held together by their common attraction for the shared pair of electrons/the electrostatic attraction between the positive nuclei and the negative shared pair of electrons.

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7
Q

Are the electrons shared equally in a covalent bond?

A

Yes

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8
Q

Why do atoms move together?

A

The electrons in orbit around the nucleus are negatively charged and the nucleus is positively charged. The covalent bond is created when the negatively charged electrons of one atom are attracted to the positively charged nucleus of another atom.

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9
Q

Why do atoms eventually stop moving towards each other

A

The attraction pulls the atoms together until the POSITIVE NUCLEI start to REPEL each other, it is then a balance is reached.

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10
Q

What is ionic bonding and what does this create?

A

Ionic bonds are the electrostatic attraction between positive and negative ions. Ionic compounds form lattice structures of oppositely charged ions.

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11
Q

What is the London Dispersion Forces of attraction between?

A

Between monatomic atoms and small discrete molecules.

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12
Q

What is the force caused by in London Dispersion Forces?

A

The force is caused by uneven distribution of the constantly moving electrons around the nuclei of the atoms. The atom has an electron deficient side which is very slightly positive (δ+) and is attracted to a side of another atom which has an excess of electrons which is very slightly negative (δ-) . THIS IS CAUSED BY THE MOVEMENT OF THE ELECTRONS IN ATOMS.

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13
Q

Are London Dispersion Forces easily broken and what element and compounds can they be found?

A

Yes. Elements and compounds with very low melting and boiling points.

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14
Q

What group number are the halogens and what properties do they have?

A

Group 7 and they kill bacteria.

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15
Q

What group are the alkalis and what do they all have in common?

A

Group 1 and they are all very reactive.

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16
Q

What group are the alkaline earth metals?

A

Group 2

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17
Q

What is the valency of group 1 and what charge do they form?

A

1 and a +1 charge.

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18
Q

What is the valency of group 2 and what charge do they form?

A

2 and a +2 charge.

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19
Q

What is the valency of group 3 and what charge do they form?

A

3 and a 3+ charge.

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20
Q

What is the valency of group 4 and what charge do they form?

A

+4 or -4 and a charge of +4 or -4

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21
Q

What is the valency of group 5 and what charge do they form?

A

-3 and a charge of -3

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22
Q

What is the valency of group 6 and what charge do they form?

A

-2 and a charge of -2

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23
Q

What is the valency of group 7 and what charge do they form?

A

-1 and a charge of -1

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24
Q

What accounts for higher melting and boiling points within London Dispersion Forces?

A

AS you go down a group for instance group 7, the molecules get bigger with more electrons meaning the negative dipoles are stronger thus the melting and boiling points increase.

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25
Q

What does the London Dispersion Forces cause the formation of?

A

TEMPORARY DIPOLES.

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26
Q

What are the diatomics?

A

Hydrogen, nitrogen, oxygen, fluorine, chlorine, iodine, bromine.

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27
Q

What are diatomics?

A

Molecules composed of only two atoms.

28
Q

What are known as the covalent molecular structures?

A

Hydrogen, oxygen, nitrogen, phosphorus, sulphur, the halogens, chlorine nanotubes and the fullerenes.

29
Q

Give an account of the covalent molecular of nitrogen?

A

Nitrogen is the most common gas in the air (around 80%). The two nitrogen atoms are held together by three strong covalent bonds (triple bond). The nitrogen molecules are held together by weak London Dispersion Forces.

30
Q

Give an account of the covalent molecular of oxygen?

A

Oxygen is vital to sustain life and takes part in many chemical reactions such as combustion and corrosion. Oxygen atoms are held together by two strong covalent bonds (double bond). Similar to nitrogen the oxygen molecules are held together by weak London Dispersion Forces.

31
Q

Give an account of the covalent molecular of chlorine?

A

Chlorine is very reactive and like most of the halogens can be dangerous and used as a disinfectant. The two chlorine atoms are held together by one strong covalent bond (single bond). The chlorine molecules are held together by weak London Dispersion Forces.

32
Q

Give an account of the covalent molecular of Sulphur?

A

Sulphur is a yellow solid which can be recognised by its bad smell. Due to elemental sulphur forming a closed eight members covalently bonded ring (S8), the London Dispersion Forces between the S8 molecules are strong which makes sulphur a solid at room temperature.

33
Q

Give an account of the covalent molecular of Phosphorus?

A

Phosphorus was extracted from urine in the 17th century and glows in the dark, it can appear in a ‘ red ‘ and ‘ white ‘ configuration both being highly poisonous. Phosphorus makes use of strong single covalent bonds to form P4 molecules. Like sulphur the London Dispersion Forces between molecules are strong which allows it to exist as a solid.

34
Q

Give an account of the covalent molecular of Fullerenes?

A

Fullerenes were discovered in 1985 in ‘ soot ‘ the fullerenes are discrete, covalently bonded molecules of carbon with the smallest being C60. Named after the American architect Buckminster Fuller who designed the Geodesic Dome which has a similar shape. The
‘ buckyball ‘ has a spherical shape which contains only carbon atoms which are bonded in 5 and 6 members rings.

35
Q

Give an account of the covalent molecular of Nanotubes?

A

Nanotubes are cylindrical fullerenes. These tubes of carbon can range from less than a micrometer to several millimetres in length. Their unique molecular structure results in extraordinary properties, including high tensile strength, high electrical and heat conductivity, and are relatively stable.

36
Q

How can London Dispersion Forces increase in strength at lower temperatures?

A

London Dispersion Forces increase in strength at lower temperatures due to a decrease in molecular vibration.

37
Q

What is not affected in the London Dispersion Forces wether the covalent molecules are solid liquid or gas?

A

The strong covalent bond holding the atoms together are not affected.

38
Q

Give an account of the covalent network structure of Boron?

A

Boron is a rare as it is extremely difficult to separate from its compounds. Chemically boron is inert and resistant to attack by boiling acid, Boron has a strong covalent network structure which makes it almost as hard as diamond and a poor conductor of electricity at room temperature. Compounds of boron are found in ‘pyrex’ glass.

39
Q

What are elements that can bond in a covalent network structure?

A

Boron Carbon and Silicon.

40
Q

In their natural state what do the elements boron, carbon and silicon comprise of?

A

A vast three dimensional lattice structure where each atom is bonded by strong covalent bonds in a continuous network.

41
Q

Give an account of the covalent network structure of Silicon?

A

Silicon rarely occurs as the pure element in nature. 90% of the Earth’s crust is composed of silicates, making silicon the 2nd most abundant element in the Earth’s crust after oxygen. It has a covalent network structure, medium reactivity and is best known as a semiconductor used in the ‘silicon chip’ in computers.

42
Q

Give an account of the covalent network structure of Carbon?

A

Carbon is a part of the fullerenes, which are small discrete molecules. Other forms of carbon are diamond, graphite and sugar charcoal, (normal charcoal has impurities) and have large covalent network structures.

43
Q

Give an account of the covalent network structure of Diamond?

A

Diamond is the hardest substance on earth, it has a giant covalent network structure with each carbon bonded to four other carbons. It does not conduct electricity, is unreactive and is used as jewellery and as a cutting tool. A process to make synthetic diamond has been discovered which requires high temperatures and pressure.

44
Q

Give an account of the covalent network structure of Graphite?

A

Graphite is the only form of a non-metal that conducts electricity. Unlike diamond the carbon atoms in graphite are only bonded three times. This leaves a mobile electron to conduct electricity which is found in-between the graphite layers. the layers of graphite are easily removed from the covalent network structure allowing graphite to be used in pencils and as a lubricant.

45
Q

Why is graphite a conductor of electricity?

A

Unlike diamond the carbon atoms in graphite are only bonded three times. This leaves a mobile electron (delocalised electron) to conduct electricity which is found in-between the graphite layers.

46
Q

Why do the noble gases not bond/unreactive?

A

The noble gases do not bond due to the outer electrons having a ‘STABLE OCTET’, with the exception of helium which has a filled outer shell of two electrons.

47
Q

Are the noble gases diatomic and why is this?

A

No, they are monatomic as they consist of only one atom.

48
Q

Why are the noble gases very unreactive?

A

Due to the filled outer shell in the noble gases they are very unreactive.

49
Q

What happens when electricity passes through a noble gas and what are they used for because of this property?

A

When electricity passes through a noble gas the glow and are used in advertising lighting and found inside bulbs and strip lighting.

50
Q

Apart from the fact they glow, why else are the noble gases found in bulbs and lighting?

A

As they are very unreactive the metal strip which glows does not erode as fast as it would with oxygen.

51
Q

What are intramolecular bonds?

A

Bonds which join atoms within the molecule.

52
Q

What are intermolecular bonds?

A

Bonds which join individual molecules.

53
Q

What are properties of covalent bonding (including network) related to a change of state?

A

Very high melting and boiling points which require intermolecular bonds to be broken down for a change of state to occur.

54
Q

When a substance changes state i.e. from solid to liquid, what bonds have to be broken or weakened?

A

Intramolecular and intermolecular bonds.

55
Q

What are properties of London Dispersion Forces related to a change of state?

A

Very low melting and boiling points which require intermolecular bonds to be broken down for a change of state to occur.

56
Q

What have higher melting and boiling points the left hand side or the right hand side of the periodic table?

A

Higher on the left of the periodic table and fall dramatically for elements on the right as the type of bonding changes.

57
Q

How does reactivity differ in group 1 and why is this?

A

As you move down group 1 there is an extra shell of electrons being added. This makes the attraction between the outer electron and the positive nucleus weaker, therefor easier to remove the outer electron. Hence more reactive the further you go down.

58
Q

What do the halogens form when they accept electrons?

A

Halide ions

59
Q

How does reactivity differ with the halogens and why is this?

A

The halogens reactivity decreases the further they are down the table. This is because the halogen molecule with the more exposed nucleus , has the greater ability to attraction and is therefore more reactive.

60
Q

How does the structure of a fullerene differ from that of diamond?

A

Fullerens consists of discrete molecules where as diamond is a covalent network.

61
Q

Why are noble gases used in a lot of things instead of air?

A

The noble gases are unreactive and will not react (burn/corrode) with things that air would.

62
Q

What is the test for saturated and unsaturated hydrocarbons?

A

The bromine water test - unsaturated will decolourise the bromine water due to the double bond whereas saturated will not decolourise the bromine water.

63
Q

Why does the H+ ion not exist?

A

H+ has no electrons

64
Q

What is the reaction of the first ionisation energy of sodium?

A

Na(g) = Na+(g) + e-

65
Q

Why does the first ionisation energy down a group decrease?

A

The outermost electron being removed is further from the nucleus and increased shielding down the group.

66
Q

How can you decrease the activation energy?

A

By adding a catalyst.

Z/ HIGHER Chemistry (25 decks)

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