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Chemistry > C3 : Structure and Bonding > Flashcards

C3 : Structure and Bonding Flashcards

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1
Q

Why are ionic compounds crystals?

A

Due to their regular structure of the ionic lattice.
- the ions are joined by strong ionic bonds between oppositely charged ions

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2
Q

Why do ionic compounds have high melting/boiling points?

A

A lot of energy is needed to break the bonds bc they’re very STRONG.

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3
Q

Why can a solid ionic substance NOT conduct electricity but a molten/aqueous ionic substance can? (6)

A
  • When solid, ions are bonded together by the lattice in a fixed position .
  • ions cant move to carry the electrical charge
  • in liquid, ions can break free from lattice
  • able to move, bc supplied with enough energy to become a liquid
  • can carry electrical charge
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4
Q

What do ionic bonds form between?

A

Metal / non-metal - conduct in molten/aqueous state

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5
Q

What do covalent bonds form between?

A

2 non- metals
- don’t conduct electricity/heat

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6
Q

Why do the simple covalent bonds have low MP/BP?

A

Bc intermolecular forces are relatively weak - less energy is needed to OVERCOME the forces
Intermolecular forces are weaker than covalent bonds - covalent bonds aren’t broken

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7
Q

compare the strength of bonds between atoms in the molecule to the forces that exist between the different molecules. (2)

A

The strength of the coaled bonds are stronger Tham the intermolecular forces - they are weak.

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8
Q

Examples of SIMPLE covalent bonds. (3)

A

H20 - water
CO2 - carbon dioxide
NH3 - ammonia

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9
Q

Examples of giant covalent bonds. (5)

A

Diamond
graphite
graphene
fullerenes
silicon dioxide

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10
Q

Why do giant covalent bonds have high MP/BP?

A
  • Bc they don’t form molecules
    -A lot of energy is needed to break the strong covalent bonds
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11
Q

What are graphite’s properties and why do they have these properties? (3)

A

Soft/slippery - layers are far apart
- forces between layers are weak
- easy to separate layers /slide

High MP
- difficult to break strong covalent bonds

Conducts Electricity/Heat
- 3 of the 4 outer electrons are held in place in the layer
- the 4th electron is is DELOCALISED. Electron current can be carried/travel through material.

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12
Q

What are allotropes?

A

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

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13
Q

what are the allotropes of carbon?

A

Diamond
Graphite
Graphene
Fullerenes

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14
Q

Why do metals have high BP/MP?

A
  • takes a lot of energy to separate metal ions from fixed positions, as electrostatic forces are very strong
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15
Q

How are ions held together in a metal? (3)

A
  • lattice structure of positive ions
  • with delocalised electrons/free electrons
    -Strong electrostatic forces between the electrons and + ions bond the metal ions together.
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16
Q

How does the structure and bonding in metals allow them to bent and shaped?

A
  • layers of atoms are able to SLIDE easily over each other
17
Q

Properties of diamond and uses.

A
  • very hard - lots of covalent bonds
    - takes a lot of energy to break these bonds
    - giant lattice structure
  • BAD conductor of ELECTRICITY
    - no delocalise electrons

USED FOR : jewellery
cutting tools/blade edges

18
Q

Properties of graphene. SFC

A

STRONG - due to strong covalent bonds/unbroken pattern
CONDUCTS ELECTRICITY/HEAT - has free electrons to carry current/heat
3/4 electrons are bonded , 4th Is delocalised
FLEXIBLE - bonds between atoms are flexible

19
Q

What can fullerenes be used for and what properties allow this?

A

-can CAGE other molecules - good for DRUG DELIVERY
- large SURFACE AREA - make them good industrial catalysts
WEAK intermolecular forces , so SLIPPERY/LOW MP - lubricants

20
Q

describe the nature of chemical bonding in ionic strictures? (3)

A
  • giant lattice structure
    -held together by strong electrostatic forces between oppositely charged ions
    -theses forces act in all directions
21
Q

why are alloys harder than pure metals?

A
  • atoms/ions/particles are different sizes
  • layers can’t slide over eachother
22
Q

NANOPARTICLES SIZE?

A

(1X10-9) - (1X10-7)
1nm - 100nm

23
Q

surface area: volume ration equyation?

A

SA / VOL

24
Q

USES OF nanoparticles ?

A
  • high SA:V - CATALYSTS
    DRUG DELIVERY - absorbed into body easily
    ELECTRIC CIRCUITS - conductor
    POLYMER FIBRES - (surgical masks/wound dressing) - ANTIBACTERIAL
    COSMETICS
25
Q

what are effects on health by using nanoparticles?

A
  • jnot sure LONG TERM EFFECTS
  • SHld be clearly labelled so consumer can decide whether to use product or not
  • could DAMAGE CELLS/DAMAGE ENVIRON
26
Q

how are nanoparticles able to catalyse reaction?

A
  • A catalyst provides an alternative reaction pathway with lower activation energy
  • Often by creating more surface area for reactant particles to collide
  • As nanoparticles have a high surface area to volume ratio
  • They provide much more surface area for catalytic activity to occur
  • Hence increasing the rate of reaction

Chemistry (15 decks)

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