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Chemistry > Chem B > Flashcards

Chem B Flashcards

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1
Q

How are covalent bonds formed

A

By atoms sharing a pair of electrons

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2
Q

Which type of atoms form covalent bonds between them?

A

non-metals

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3
Q

Describe the structure and bonding of a giant coval
substance.

A

billions of atoms bonded together by strong covalent
bonds

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4
Q

Describe the structure and bonding of small molecules.

A

small numbers of atoms group together into molecules with strong covalent bonds between the atoms and weak intermolecular forces between the molecules

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5
Q

Describe the structure and bonding of polymers.

A

many identical molecules joined together by strong covalent bonds in a long chain, with weak intermolecular forces between the chains

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6
Q

Why do giant covalent substances have high melting points?

A

it takes a lot of energy to break the strong covalent bonds between the atoms

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7
Q

Why do small molecules have low melting points?

A

only a small amount of energy is needed to break the weak intermolecular forces

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8
Q

Why do large molecules have higher melting and boiling points than small molecules?

A

the intermolecular forces are stronger in large molecules

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9
Q

Why do most covalent substances not conduct electricity

A

do not have delocalised electrons or ions

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10
Q

Describe the structure and bonding in graphite.

A

each carbon atom is bonded to three others in hexagonal rings arranged in layers - it has delocalised electrons and weak forces between the layers

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11
Q

Why can graphite conduct electricity?

A

the delocalised electrons can move througn the grapnite

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12
Q

Explain why graphite is soft.

A

layers are not bonded so can slide over each other

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13
Q

What is graphene?

A

one layer of graphite

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14
Q

Give two properties of graphene.

A

strong, conducts electricity

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15
Q

What is a fullerene?

A

hollow cage of carbon atoms arranged as a sphere or a
tube

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16
Q

What is a nanotube?

A

hollow cylinder of carbon atoms

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17
Q

Give two properties of nanotubes.

A

high tensile strength, conduct electricity

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18
Q

Give three uses of fullerenes.

A

lubricants, drug delivery (spheres), high-tech electronics

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19
Q

What is an ion?

A

atom that has lost or gained electrons

20
Q

Which kinds of elements form ionic bonds?

A

metals and non-metals

21
Q

What charges do ions from Groups 1 and 2 form?

A

Group 1 forms 1+, Group 2 forms 2+

22
Q

What charges do ions from Groups 6 and 7 form?

A

Group 6 forms 2-, Group 7 forms 1-

23
Q

Name the force that holds oppositely charged ions together.

A

electrostatic force of attraction

24
Q

Describe the structure of a giant ionic lattice.

A

regular structure of alternating positive and negative ions, held together by the electrostatic force of attraction

25
Q

Why do ionic substances have high melting points?

A

electrostatic force of attraction between positive and negative ions is strong and requires lots of energy to break

26
Q

Why don’t ionic substances conduct electricity when
solid

A

ions are fixed in position so cannot move, and there are no delocalised electrons

27
Q

When can ionic substances conduct electricity?

A

When melted or dissolved

28
Q

Why do ionic substances conduct electricity when melted or dissolved?

A

ions are free to move and carry charge

29
Q

Describe the structure of a pure metal.

A

layers of positive metal ions surrounded by delocalised
eeatons

30
Q

Describe the bonding in a pure metal.

A

strong electrostatic forces of attraction between metal
Ions dnic acrocalised erectrons.

31
Q

What are four properties of pure metals?

A

malleable, high melting/boiling points, good conductors or electricity, good conductors or thermal energy

32
Q

Explain why pure metals are malleable.

A

layers can slide over each other easily

33
Q

Explain why metals have high melting and boiling points.

A

electrostatic force of attraction between positive metal ions and delocalised electrons is strong and requires a lot of energy to break

34
Q

Why are metals good conductors of electricity and of thermal energy?

A

delocalised electrons are free to move through the metal

35
Q

what is an alloy

A

mixture of a metal with atoms of another element

36
Q

Explain why alloys are harder than pure metals.

A

different sized atoms disturb the layers, preventing them from sliding over each other

37
Q

Structure of a metal

A

Layers of positive metal ions in a sea of delocalised electrons

38
Q

Malleable

A

The ability to bend

39
Q

Why are metals malleable?

A

The layers of of ions can slide over each other

40
Q

Melting point?

A

High melting point as a lot of energy is needed to break the metallic bond and electrostatic force between the positive ions and negative electrons

41
Q

Electrical conductivity of metallic bonding

A

Can conduct electricity as the sea of delocalised electrons can carry the electrical current through the material

42
Q

Alloy metallic bonding

A

A mixture of two different metals

43
Q

Why are alloys harder than pure metals in metallic bonding

A

They have different sized atoms so the layers can not slide over each other

44
Q

Covalent bonding

-Happens between…..

A

Two non-metals

45
Q

How does covalent bonding form?

A

Non metals share a pair of electrons

46
Q

Metals structure and properties

A

The atoms that make up metals form layers. The electrons in the outer shells of the atoms are delocalised - this means they are free to move through the whole
The positive metal ions are then attracted to these delocalised electrons by the electrostatic force of attraction.
Some important properties of metals are:
pure metals are malleable because the layers can slide over each other
• they are good conductors of electricity and of thermal energy because delocalised electrons are free to move through the whole structure
• they have high melting and boiling points because the electrostatic force of attraction between metalions and delocalised electrons is strong so lots of energy is needed to break it.

47
Q

Giant ionic lattice

A

When metal atoms non-metal atoms you end up with positive and negative ions. These are attracted to each other by the strong electrostatic force of attraction. This is called ionic bonding. The electrostatic force of attraction works in all directions, so many billions of ions can be bonded together in a 3D structure.

Chemistry (3 decks)

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