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지시엣이 Chemistry > C2 - Bonding, Structure and Properties of Matter > Flashcards

C2 - Bonding, Structure and Properties of Matter Flashcards

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1
Q

Ions

A

Charged particles which can be singles atoms or a group of atoms

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2
Q

Why do atoms lose or gain electrons to form ions?

A

To get a full outer shell, “a stable electronic structure”

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3
Q

What happens when metals form ions?

A

The lose electrons from their outershells to form positive ions

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4
Q

What happens when non-metals form ions?

A

They gain electrons into their outer shell to form negative ions`

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5
Q

What groups are most likely to form Ions?

A

Groups 1, 2, 6, 7

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6
Q

What is ionic bonding?

A

When a metals and non-metal react together, the metals atom loses electrons to form a positively charged ion and the non-metal gains these electrons to form a negatively charged ion. These oppositely charged ions are strongly attracted to one another by electrostatic forces

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7
Q

What are dot and cross diagrams used for?

A

To show the arrangement of electrons in an atom or ion. Each electron is represented by a dot ore a cross.

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8
Q

Why may dot and cross diagrams may not be useful?

A

They don’t show the structure of the compound, the size of the ions or how they’re arranged

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9
Q

What structure do ionic compounds have?

A

A giant ionic lattice

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10
Q

How do the ions form a closely packed regular lattice arrangement?

A

Loads of strong electrostatic forces of attraction between oppositely charged ions, in all directions in the lattice

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11
Q

Give some similar properties of ionic compounds

A
  • High melting and boiling points
  • Can’t conduct electricity unless they are melted
  • Some can dissolve in water
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12
Q

Why do ionic compounds have high melting and boiling points?

A

Many strong bonds between the ions which means more energy to overcome the electrostatic forces of attraction

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13
Q

When can ionic compounds conduct electricity?

A

When they melt because the ions separate and are free to move in the and they’ll carry electric charge

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14
Q

When an ionic compounds dissolves in water, why can they carry electric charge?

A

Because the ions separate and are free to move in the solution

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15
Q

Covalent bonds

A

When non-metal atoms bond together and share pairs of electrons. Positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces making covalent bonds very strong. Atoms only share electrons in their outer shells. Each single covalent bond provides one extra shared electron for each atom. Each atom generally makes enough covalent bonds to fill up its outer shell. This process happens in compounds of non-metals and in non-metal elements.

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16
Q

What are some different ways of drawing covalent bonds?

A

Use dot cross diagrams, Displayed formula and 3D models.

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17
Q

Advantage for drawing covalent bonds with dot and cross diagrams

A

Useful for showing which atoms the electrons in a covalent bonds come from

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18
Q

Disadvantage for drawing covalent bonds with dot and cross

A

They don’t show the relative sizes of the atoms or how the atoms are arranged in space

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19
Q

Advantages of drawing covalent bonds with the displayed formula

A

Showing how atoms are connected in large molecules

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20
Q

Disadvantages of using displayed formulae for drawing covalent bonds?

A

They don’t show the 3d structure of the molecule or which atoms the electrons in the covalent bond have come from

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21
Q

Advantages of using 3d model for covalent bonds

A

Shows their arrangement in space next to each other

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22
Q

Disadvantages of using 3d models

A

Can quickly get confusing for large molecules where there are lots of atoms to include. They don’t show where the electrons in the bonds have come from.

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23
Q

What are simple molecular substances

A

Molecules containing a few atoms joined together by covalent bonds

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24
Q

What are some common examples of simple molecular substances

A
  • Hydrogen (H2) : Hydrogen atoms only have 1 electron so they only need 1 more to complete the first shell. (single)
  • Chlorine (Cl2): Each chlorine atom needs just one more electron to complete the outer shell. So 2 chlorine atoms can share one pair of electrons (single)
  • Oxygen (O2): Each oxygen atom needs to more electrons to complete it’s outer shell. So 2 oxygen atoms share 2 pairs (double)
  • Nitrogen (N2): Need 3 more electrons, so 2 nitrogen atoms share 3 pairs of electrons (triple)
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25
Q

Properties of Simple Molecular Substances

A
  • Held together by very strong covalent bonds (the forces of attraction between the molecules are very weak)
  • To melt or boil these, you need to break the intermolecular forces and not the covalent bonds which means they have very low melting and boiling points
  • Most of them are gases or liquids at room temperature
  • As the molecules get bigger, the strength of the intermolecular forces increase and therefore more energy is needed to break them (melting and boiling points increase)
  • Molecular compounds don’t conduct electricity simply because they aren’t charged, so there are no free electrons or ions
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26
Q

Polymers

A

Lots of small units linked together to form a long molecule that has repeating sections.

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27
Q

What are all the atoms in a polymer joined by?

A

Strong covalent bonds

28
Q

How can you find out the molecular formula of a polymer

A

Write down the molecular formula of the repeating unit brackets and put an ‘n’ outside

29
Q

Molecular formula of polythene

A

(C2H4)n

30
Q

Why do you need more energy to break the intermolecular forces in polymers?

A

Because they are larger than between simple covalent molecules so more energy is needed to break them down. This means that polymers are solid at room temperature.

31
Q

Why do polymers have lower boiling points than ionic or giant molecular compounds?

A

The intermolecular forces are still weaker than ionic or covalent bonds.

32
Q

Macromolecules

A

Giant covalent Structures

33
Q

Giant covalent structures

A

All the atoms are bonded to each other by strong covalent bonds.

34
Q

Why can’t giant covalent structures conduct electricity?

A

They don’t contain charged particles, not even when molten (except for some exceptions)

35
Q

Name 3 Giant Covalent Structures

A
  • Diamond : Each carbon atom forms 4 covalent bonds in a very rigid giant covalent structure
  • Graphite : Each carbon atoms forms 3 covalent bonds to create layers of hexagons. Each carbon atom also has one delocalised (free) electron
  • Silicon dioxide
36
Q

Allotropes

A

Different structural forms of the same element in the same physical state

37
Q

Give some Allotropes of Carbon

A

Diamond, Graphite and Graphene

38
Q

Diamond covalent bonds

A

A giant covalent structure which each form 4 covalent bonds (which makes it really hard)

39
Q

Why is Diamond’s melting/boiling point so high?

A

More energy is needed to break the strong covalent bonds

40
Q

Why does diamond not conduct electricty?

A

It has no free electrons or ions

41
Q

Graphite covalent bonds

A

Only 3 atoms form 3 covalent bonds, creating sheets of carbon atoms arranged in hexagons.

42
Q

Why is graphite used as a lubricating material?

A

There aren’t any covalent bonds between the layers - they’re only held together weakly so they’re free to move over each other which makes it soft and slippery

43
Q

Why can graphite conduct electricity and thermal energy?

A

Only 3 of each carbon’s 4 outer electrons are used in bonds, so each carbon atom has one electron that’s delocalised (free) and can move.

44
Q

Graphene

A

A sheet of carbon atoms joined together in hexagons. Because it is only 1 atom thick, it is considered a 2-dimensional substance. The network of covalent bonds make it very strong. Very light and can be added to composite materials to improve their strength without adding much weight. Like graphite, it contains delocalised electron so it can conduct electricity through the whole structure.

45
Q

Fullerenes

A

Molecules of carbon shaped like closed tubes or hollow balls. Mainly made up of carbon atoms arranged in hexagons but can also contain pentagons or heptagons.

46
Q

Uses of fullerenes

A

To ‘cage’ other molecules which can be used for cancer patients.

47
Q

Why are fullerenes useful for industrial use?

A

They have huge surface areas for lubricants

48
Q

First fullerene discovered

A

Buckminsterfullerene (C60) which forms a hollow sphere

49
Q

Nanotubes

A

Carbon cylinders made from fullerenes. The ratio between the length and diameter is very high. They can conduct electricity and thermal energy. They are also very tensile

50
Q

Do metals consist of giant structures?

A

Yes

51
Q

Metallic bonding

A

Where the outer shell of the metal atoms are delocalised, and a strong electrostatic attraction between the positive metal and ions and the shared negative electrons which hold the atoms together in a regular structure. (The delocalised electrons in the metallic bond produce all the properties of metals)

52
Q

What are most metals solid at Room Temperature?

A

The electrostatic forces between the metal atoms and delocalised sea of electrons are very strong, so need lots of energy to be broken. This means that most compounds with metallic bonds have very high melting and boiling points, so they’re generally solid at room temperature

53
Q

Why are Metals good conductors of of electricity and heat?

A

Delocalised electrons carry electronical charge and thermal energy through the whole structure, so metals are good conductors of electrity and heat

54
Q

Why are most metals Malleable?

A

The layers of atoms in a metal can slide over each other, making metals malleable - meaning that they can be bent or hammered or rolled into flat sheets.

55
Q

Alloys

A

A mixture of 2 or more metals or a metal and another element.

56
Q

Why are alloys more useful than pure metals?

A

They are harder as pure metals are quite soft

57
Q

Why do alloys become harder?

A

Different elements have different sizes, so when another element is mixed in, the metal atoms will distort the layers of the metal atoms, making it more difficult for them to slide over each other

58
Q

What are the 3 states of matter?

A
  • Solids
  • Liquids
  • Gases
59
Q

Which state something is at certain temperature depends on how strong the forces of attraction are between the particles of the material. What determines how strong the forces are?

A
  • Material
  • Temperature
  • Pressure
60
Q

Solids

A
  • There are strong forces of attraction between particles which hold them close together in a fixed position to form a very regular lattice arrangement
  • Particles don’t move from their positions so all solids keep a definite shape and volume, and don’t flow like liquids
  • The particles vibrate about their positions, the hotter the solid becomes, the more they vibrate (which can cause them to expand slightly)
61
Q

Liquids

A
  • There’s a weak force of attraction between the particles. They’re randomly arranged and free to move past each other, but they tend to stick closely together
  • Liquids have a definite volume but don’t keep a definite shape, and will flow to fill the bottom of the container
  • The particles are constantly moving with random motion. The hotter the liquid gets, the faster they move. This causes liquids to expand slightly when ehated
62
Q

Gases

A
  • The forces of attraction between the particles is very weak - they’re free to move and are far apart. The particles in gases travel in straight lines
  • Gases don’t keep a definite shape or volume and will always fill any container
  • The particles move constantly with random motion. The hotter the gas gets, the faster they move. Gases either expand when heated, or their pressure increases
63
Q

What are some disadvantages of the particle theory?

A
  • Particles aren’t solid or inelastic and they aren’t spheres
  • Doesn’t show the forces of attraction between the particles
64
Q

Melting

A

Solid to liquid

65
Q

Boiling (evaporating)

A

Liquid to gas

66
Q

Condensing

A

Gas to liquid

67
Q

Freezing

A

Liquid to solid

지시엣이 Chemistry (10 decks)

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