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AS Chemistry - Unit 1 > Unit 1: Section 3 - Bonding And Periodicity > Flashcards

Unit 1: Section 3 - Bonding And Periodicity Flashcards

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0
Q

How are ions formed?

A

When electrons are transferred from one atom to another

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1
Q

What are the two main types of bonding?

A

Ionic and covalent

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2
Q

What group do 2+ ions come from?

A

Group 2

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3
Q

What group do 3- ions come from?

A

Group 5

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4
Q

How can you tell which ion an atom will form?

A

There group number tells you how many atoms are in their outer shell, and from that you can see how many electrons it needs to gain or lose to get a full outer shell. The number it needs to gain will give it a -charge, and any lost will give it a + charge.

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5
Q

What happens during ionic bonding?

A

Electrons are transferred from one atom to another so that they have a full outer shell. This creates ions which have opposite charges and electrostatic attractions hold positive and negative ions together creating an ionic bond.

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6
Q

Name two ionic compounds?

A

Sodium chloride and magnesium oxide

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7
Q

What diagram can you use to represent ionic bonding?

A

Dot and cross

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8
Q

Who would you figure out the ratio of atoms in sodium chloride?

A

Sodium forms a Na+ ion and chlorine forms a Cl- ion. This means one sodium will bond with chlorine as then the negative charges balance the positive charges meaning the overall charge is zero . This means the ratio is 1:1

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9
Q

What type of structure does sodium chloride form?

A

Goat ionic structure

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10
Q

What shape are sodium chloride lattices?

A

Cube

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11
Q

Do ionic compounds conduct electricity?

A

When they are molten or dissolved in a solution

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12
Q

Why do ionic compounds conduct electricity when they are molten or dissolved in a solution?

A

The ions are free to move and carry the charge

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13
Q

Do ionic compounds have high or low melting points?

A

High

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14
Q

Why do ionic compounds have high melting points?

A

The giant ionic lattices have strong electrostatic forces of attraction holding them together, which are hard to overcome increasing their melting points

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15
Q

Are ionic compounds soluble in water?

A

Yes they tend to be

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16
Q

Why do ionic compounds tend to dissolve in water?

A

Water molecules are polar, as oxygen is very electronegative compared to hydrogen. This means the oxygen atom becomes slightly negative and the hydrogen atom becomes slightly positive. The negative charges pull the ions away from the lattice and cause it to dissolve

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17
Q

What happens during covalent bonding?

A

Two atoms share electrons so they have both got full outer shells of electrons. Then both of the positive nuclei are attracted to the shared electrons

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18
Q

Do ionic and covalent happen between metals and non metals?

A

Covalent bonding - non metals

Ionic bonding - a metal and a non metal

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19
Q

Can atoms just form single covalent bonds?

A

Do double and triple too

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20
Q

What two structures can covalent bonds form?

A

Simple molecular and giant covalent structures

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21
Q

What are the two names for giant covalent carbon structures?

A

Carbon and graphite

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22
Q

It terms of bonds between the electrons what is the difference between graphite and diamond?

A

Graphite carbon atoms only form the bonds where as diamond forms four

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23
Q

What does the structure of graphite look like?

A

Sheets of hexagons with delocalised electrons

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24
Q

Why can graphite be used in pencils?

A

The weak van der waals forces between the layers of graphite are easily broken so the sheets can slide over each other, and can be transferred onto paper

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25
Q

Can diamond graphite conduct electricity and why?

A

Graphite as it’s delocalised electrons are free to carry the current

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26
Q

Why is graphite used to make strong lightweight sports equipment?

A

The strong covalent bonds means it is strong, and as the lights are quite far apart compared to the lengths of the covalent bonds it means it has a low density and so is light

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27
Q

Why is graphite and diamond insoluble?

A

Covalent bonds in the sheets and between atoms are too difficult to break

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28
Q

Does graphite have a high or low melting point and why?

A

High as the strong covalent bonds are hard to break

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29
Q

What shape is the structure of diamond?

A

Tetrahedral

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30
Q

What properties does strong covalent bonds give diamond?

A

Very high melting point and it is very hard

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31
Q

Why is diamond a good thermal conductor?

A

Vibrations can travel easily through the stiff lattice meaning heat can pass through it easily

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32
Q

What is dative covalent bonding?

A

When both electrons come from one atom in a covalent bond

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33
Q

What is the atom called if it gives both pairs of electrons in dative covalent bonding?

A

The donor atoms

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34
Q

How can you represent dative covalent bonding on a diagram?

A

An arrow pointing away from the donor atoms

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35
Q

What does molecular shape depend on?

A

The number of electron pairs in the outer shell of the central atom

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36
Q

What is a charge cloud?

A

An area where you have a really big chance of finding an electron pair

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38
Q

Shared electrons are called?

A

Bonding pairs

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39
Q

Unshared electrons are called?

A

Lone pairs

40
Q

Between bonding pairs and lone pairs which ones have the greatest repulsion?

A

Lone pairs

41
Q

Do electron clouds repel or attract each other and why?

A

They repel each other because they are all negatively charged so will each other as much as they can

42
Q

Do lone pair charges clouds repel more than bonding pair charge clouds?

A

Lone pair charge clouds

43
Q

In what size order do the angles between bonding pairs of electrons and lone pairs of electrons go?

A

Lone pair/lone pair - biggest
Lone pair/bonding pair
Bonding pair/bonding pair - smallest

44
Q

What is the valence shell electron pair repulsion theory?

A

How lone pairs and bonding pairs of electrons repel each other

45
Q

How to draw electron on a molecule diagram to show which way they are pointing?

A

Normal lines show bond is in line with the paper, wedges show the bonds are pointing towards you and dotted lines show they are pointing away from you

46
Q

What is the bond angle and shape for an atom with two bonding electron pairs around the central atom?

A

180 - linear

47
Q

What is the bond angle and shape for an atom with three bonding pairs of electrons around the central atom?

A

120 - trigonal planar

48
Q

What is the bond angle and shape for an atom with four bonding pairs of electrons around the central atom?

A

109.5 - tetrahedral

49
Q

What is the bond angle and shape for an atom with three bonding pairs and one lone pair around the central atom?

A

107 - trigonal pyramidal

50
Q

What is the bond angle and shape for an atom with two bonding pairs of electrons and two lone pairs of electrons?

A

104.5 - non - linear

51
Q

What are the bond angles and shape for an atom with five bonding pairs of electrons?

A

Three are on a trigonal planar so have the bonding angle of 120, the other two will be at 90 to the line - tigonal bipyramidal

52
Q

What are the bond angles and shape for an atom with six bonding pairs of electrons?

A

90 - octahedral

53
Q

What shape molecules has the bond angle of 180?

A

Linear

54
Q

What shape molecules has the bond angle of 120?

A

Trigonal planar

55
Q

What shape molecules has the bond angle of 109.5?

A

Tetrahedral

56
Q

What shape molecules has the bond angle of 107?

A

Trigonal pyramidal

57
Q

What shape molecules has the bond angle of 104.5?

A

Non linear

58
Q

What shape molecules has the bond angle of 90 and 120?

A

Trignal bipyramidal

59
Q

What shape molecules has the bond angle of 90?

A

Octahedral

60
Q

What is electronegativity?

A

The ability of an atom to attract the bonding electrons in a covalent bond

61
Q

What is an example of non polar covalent bonds?

A

In diatomic gases

62
Q

What is meant by a non polar covalent bond?

A

If atoms have equal electronegativity they are equally attracted to both nuclei and so the shared pair of electrons will be found in the middle of both atoms and so they are non polar

63
Q

What makes a covalent bond polar?

A

If atoms have different electronegativities, the bonding pair of electrons will be more attracted to the more electronegative ones, moving it closer ot that one making it polar

64
Q

What a diploe caused by in a polar covalent bond?

A

When the shared electrons move closer to one atom it’ll make that atom slightly negative and the other one slightly positive. This difference in charge causes a dipole.

65
Q

Are intermolecular forces stronger or weaker than ionic bonds?

A

Weaker

66
Q

What are the three types of intermolecular forces you need to know about?

A

Van deer Waals, permanent dipole-diploe forces and hydrogen bonding

67
Q

What is another name for van der waals forces?

A

Induced dipole-diploe forces

68
Q

How are induced dipole-dipole forces caused?

A

Electron clouds are constantly moving, at any one point the electrons in the atom are more likely to be one side than the other. This makes one side slightly negative and the other slightly positive creating a temporary dipole. This dipole can cause another temporary dipole in the neighbouring atom because of the slight charges. The two dipoles are then attracted to each together

69
Q

With induced diploe-diploe forces why do they keep changing?

A

The electron are constantly moving so the diploes are continually be created and destroyed

70
Q

How are iodine molecules held together?

A

Iodine atoms are held together in pairs by strong covalent bonds. And then these molecules are then held together in a molecular lattice arrangement by weak van der waals attractions ( temporary dipole-dipole forces)

71
Q

Why do larger molecules have larger van der waals forces?

A

They have a larger surface area and so have more of the electron cloud exposed they also have larger electron clouds =

72
Q

Why does the boiling point increase as you go down the noble gases?

A

Increased number of electrons, bigger electron cloud, stronger van de waals forces which are harder to overcome and so increasing the boiling points

73
Q

How are permanent dipole diploe forces caused?

A

The slightly positive and slightly negative charges on polar molecules cause weak electrostatic forces of attraction between the molecules creating a permanent dipole dipole force

74
Q

What is the strongest type of intermolecular force?

A

Hydrogen bonding

75
Q

What does hydrogen have to be covalently bonded to for hydrogen bonding to happen?

A

Fluorine, nitrogen and oxygen

76
Q

What happens during hydrogen bonding?

A

The fluorine, nitrogen and oxygen atoms are so electronegative that they draw the bonding electrons away from the hydrogen atom. As the bond is now so polarised and hydrogen has such a high charge density because it so small the hydrogen forms another bond with a lone pair of electrons

77
Q

How can you represent a hydrogen bond on a diagram?

A

Dotted line

78
Q

What about bonding makes ice less dense than water?

A

Ice has more hydrogen bonds than water, and as hydrogen bonds are relatively bonds it means the H20 molecules are more spread out making it less dense

79
Q

Metal elements exist as what structures?

A

Giant metallic lattices

80
Q

What does metallic bonding evolve?

A

There are negative delocalised electrons free to move around the metal, which leaves a positive metal ion. The positive metal ions are attracted to the delocalised negative electrons forming a metallic bond and holding it together in a closely packed lattice

81
Q

How is melting point affected by metallic bonding?

A

The more delocalised electrons per atom there are the stronger the electrostatic forces and so the stronger the metallic bonds increasing the melting point

82
Q

What about metallic bonding makes metals malleable?

A

As there are no bonds holding specific ions together they are free to slide over each other and therefore making them malleable

83
Q

What about metallic bonding means metals can conduct electricity?

A

They have delocalised electrons which are free to move and pass on the current

84
Q

Why are metals insoluble?

A

The metallic bonds are too strong

85
Q

Describe the particles in a solid?

A

They are very close together, giving it a high density and making it incompressible, the particles vibrate around their fixed point and cant move freely

86
Q

Describe the particles in a liquid?

A

They have a similar density to a solid and are virtually incompressible however they can move round freely and randomly

87
Q

Describe the particles in a gas?

A

The particles have a much lower density and are much further apart they move around freely

88
Q

A row in the periodic table is called a?

A

Period

89
Q

A column in the periodic table is called a?

A

Group

90
Q

Do elements in the same period have the same around or electrons in the outer shell?

A

No, they have the same number of electron shells, atoms in the same group have the same number of electrons in the outer shell

91
Q

What happens to the atomic radius along a period 3?

A

Decreases

92
Q

Why does atomic radius decrease along a period 3?

A

Along a period the number of protons increase and so the positive charge of the nucleus increases. The means the electrons are more strongly attracted and are pulled closer to the nucleus making the radius smaller

93
Q

What is the general trend for melting and boiling points along period 3?

A

From sodium to silicon they increase and then from silicon to argon it decreases

94
Q

Why do the melting points from sodium, magnesium to aluminium generally increase?

A

They are metals and so as you go along the period they have more delocalised electrons and more protons increasing the attraction and so the strength of the metallic bond and so the melting and boiling points

95
Q

Why does the melting and boiling point increase up till silicon in period 3?

A

Silicon is a macromolecular, and has strong covalent bonds linking all the atoms together requiring a lot of energy to break the bonds

96
Q

Why do the melting and boiling points begin to decrease from phosphorus, sulphur, chlorine to argon?

A

Because of the weaker Van der waals forces as you go along as they are smaller. (Silicon is slightly bigger than them all so there is a slight increase)

97
Q

What is periodicity?

A

The trends as you go along the periodic table

AS Chemistry - Unit 1 (4 decks)

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