2.1 Bonding, Structure and Properties Flashcards

1
Q

Properties of metals (5)

A
  • malleable and ductile
  • conduct electricity
  • conduct heat
  • high melting and boiling points
  • react with oxygen to form basic oxides (reactivity varies)
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2
Q

Structure of metallic bonding

A

Electrons from outer shells of atoms are delocalised- free to move throughout the structure

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3
Q

Why are there strong metallic bonds in metals and what makes them so strong

A

Positive ions share delocalised electrons
The bond is strong because of strong electrostatic forces between positive metal ions + and negative electrons -

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4
Q

Explain the electrical conductivity of metals

A

Delocalised electrons carry electrical charge throughout the structure

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5
Q

Explain the thermal conductivity of metals

A

Delocalised electrons and closely packed ions transfer energy throughout the structure by conduction
Free electrons move faster and conduct heat, also vibration of particles

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6
Q

Why are metals malleable and ductile

A

Layers of metal ions can slide past each other when hammered/stretched

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7
Q

Why do metals have high melting and boiling points

A

Large amounts of energy are needed to break the strong metallic bonds

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8
Q

What happens to the melting and boiling points of metals as you move across a period and why

A

Increase
There are more delocalised electrons, increasing the (electrostatic forces &) attraction between the + ions and - free electrons (stronger bonds)

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9
Q

What is an ion

A

A charged particle

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10
Q

Giant ionic structure definition

A

Positive and negative ions held together by strong electrostatic forces in a regular 3D lattice
Each + ion attracts all the - ions around it

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11
Q

Why do giant ionic structures have high melting and boiling points

A

Due to strength of electrostatic forces between the ions

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12
Q

When do giant ionic structures only conduct electricity and why

A

Only when dissolved or molten
Only them are the ions free to move to carry the charge

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13
Q

Why are giant ionic compounds brittle

A

Ion layers are shifted and jump over each other
Ions of the same charge are brought side by side and repel each other

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14
Q

Properties of giant ionic structures

A

High melting and boiling points
Conduct electricity when dissolved or molten

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15
Q

What are simple molecular/covalent structures and examples

A

A few atoms held together by covalent bonds
H, H20, CO2

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16
Q

Properties of simple covalent/molecular structures

A

Low melting and boiling points
Do not conduct electricity

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17
Q

Explain why simple covalent structures have low melting and boiling points

A

Due to weak inter molecular forces (forces between molecules)

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18
Q

Explain why simple molecular/covalent structures don’t conduct electricity

A

No free electrons to carry electric current

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19
Q

Arrangement of giant covalent structures

A

Lots of atoms held together by covalent bonds into giant lattices

20
Q

Why are giant covalent structures extremely strong

A

Because of the large number of covalent bonds in the structure

21
Q

2 examples of giant covalent structures- allotropes of carbon- bonding structure (each carbon atom bonded to __others)

A

Diamond 💎- each carbon atom bonded to 4 others
Graphite ✏️ - each carbon atom bonded to 3 others

22
Q

Allotrope definition

A

A different form of the same element with a different structure

23
Q

Properties of diamond 💎

A

Does not conduct electricity (no free electrons)
Very strong as very strong bonds

24
Q

Uses of diamond 💎

A

Drill bits
Glass cutting
Jewellery

25
Q

Property of graphite

A

Conducts electricity - delocalised electrons between layers carry charge

26
Q

Uses of graphite

A

Used in pencils ✏️ and lubricants - layers can Slide Over each other.

27
Q

Single bond - how many electrons shared

A

1 pair

28
Q

Double bond - how many electrons shared

A

2 pairs shared

29
Q

Carbon nanotubes, fullerenes and graphemes are all what

A

Allotropes of carbon

30
Q

What are carbon nanotubes

A

Types of fullerene
Graphite layers form and then roll up into tubes

31
Q

Why are carbon nanotubes so strong

A

Because of the covalently bonded hexagonal sheets

32
Q

Why do carbon nanotubes conduct electricity

A

Because of the free electrons

33
Q

Uses of carbon nanotubes

A

Strength: boats, resins, bike components
Proposed uses: in miniature electronic circuits

34
Q

Properties of other fullerenes (balls or cages) and uses

A

Very strong
Used to trap molecules- carrying drugs through the body

35
Q

Graphene - what is it and properties

A

One layer of graphite
Thinnest yet strongest material discovered
Best conductor of heat/electricity

36
Q

Do individual atoms have the same properties as their bulk form
Why?
What is another example of this

A

No!
Because of the arrangements of the atoms (different arrangements =different properties)
Nano particles

37
Q

Nano scale silver particles uses

A

Used to kill micro organisms- antiseptic uses

38
Q

Titanium dioxide uses

A

Blocks UV light -used in transparent sunscreen (advantages)
used in cosmetics

39
Q

Possible risks of using nano particles

A

Damaging to the environment (silver and titanium dioxide
Can be absorbed through the skin
We don’t know their full effects yet

40
Q

What do smart materials do

A

Change reversibly with a change in their surroundings

41
Q

Thermochromic pigments-what did they do and uses

A

Change colour with temperature
Mugs, battery power indicators

42
Q

Photochromic pigments what do they do and uses?

A

Change colour with light intensity
Photochromic lenses in sunglasses

43
Q

Shape memory polymers what do they do and uses

A

Plastics that regain their shape when heated
Car bodies- repair dents
medical stitches

44
Q

Shape memory alloys what do they do and uses

A

Metal alloys that regain their shape when heated
Deformable glasses frames 👓
Thermostats
Surgical wires/plates

45
Q

Hydrogels What do they do and uses?

A

Shells that absorbable expel water
swell or shrink due to temperature or pH changes
Nappies, firefighting