Structure and Bonding

Question 1

What are the processes when matters change?

Answer 1

Gas → condensing → liquid → freezing → solid → melting → liquid → evaporating → gas

Question 2

Solids

Answer 2

Fixed shape and volume

Cannot be compressed

Question 3

Liquids

Answer 3

Fixed volume but can flow and change their shape

Occupy slightly more space than when solid

Question 4

Gases

Answer 4

No fixed shape or volume

Can be compressed easily

Question 5

Gas to liquid

Answer 5

Hotter solid → faster particles vibrate
Vibrations so strong particles break free from neighbours
Solid starts to melt as particles separate

Question 6

Liquid to gas

Answer 6

Gas condenses to liquid
Hotter a liquid is, faster particles move
Temperature rises → more and more energy is transferred from surroundings to particles
Particles escape from surface of liquid
Rate of evaporation increases
Liquid boils and bubbles of gas rise and escape within liquid

Question 7

Difference of electrons between covalent bonding and ionic

Answer 7

Sharing electrons = covalent
Transferring electrons = ionic bonding (loses or gains so positively charged as electrons are being transferred elsewhere)

Question 8

What groups gain and lose electrons?

Answer 8

Groups 5, 6, 7 = gain electrons

Groups 1, 2, 3 = lose electrons

Question 9

Ionic Bonding

Answer 9

Transferring of electrons between a metal and a non-metal → makes an ion because it gains/loses electron
Lattice
Strong electrostatic forces broken when melted or boiled
High melting and boiling points = lots of energy to break electrostatic forces of attraction between oppositely charged ions

Question 10

Ionic Bonding Electricity

Answer 10

Can conduct electricity only when molten or dissolved = have charged ions but not free-moving
Ions move around because electrons aren’t delocalised = fixed place within shells so ions move

Question 11

Giant Ionic Structures

Answer 11

High melting point
High boiling point
Because strong electrostatic forces use lots of energy to break ions

Only conducts electricity when molten or dissolved → ions in fixed positions in lattice, no freely moving charged particles

Greater change of ions, stronger the forces holding them

Question 12

Covalent Bonding

Answer 12

Low melting and boiling points
Share electrons between 2 non-metals
Making atoms stable
e.g. water and oxygen

Question 13

Intermolecular forces

Answer 13

Forces between small molecules
Intermolecular forces = weaker than covalent bonds
When small molecular substances melt or boil = weak intermolecular forces are broken

Attraction between individual molecules = weak intermolecular forces
Does not take a lot of energy to break
Intermolecular forces increase with size → larger molecules → higher melting points

Compounds made of simple molecules do not conduct electricity unless aqueous because there is no overall charge
Neutral molecules cannot carry electrical charge

Question 14

Simple Covalent Structure

Answer 14

Held together by intermolecular forced of attraction
Sharing of electrons
Melt and boil → intermolecular forces break
Water

Question 15

Giant Covalent Structure

Answer 15

Held together by covalent bonds
Diamond
Melting and boiling = covalent bonds break → lots of energy
Can’t conduct electricity → no free-moving charged particles

Question 16

Bonding in Graphite

Answer 16

Layers of carbon
Held together by covalent bonds → takes lots of energy to break
Carbon in group 4

1 electron is not attached to other carbons, so is free to move through structure

Melting and boiling points = don’t melt and boil because still have giant covalent structure
→intermolecular forces break when melts/boils (little energy)
→layers can then slide over each other

Electricity = electrons delocalised → have negative charge and are free moving

Question 17

Metallic Bonding

Answer 17

Atoms arranged in regular patterns
Electrons in outer shell of metal delocalised → free to move throughout whole structure
Electricity = because electron is negatively charged and can move → free moving charged particles so can conduct
Metal and boiling points = have to separate atom from structure → takes lots of energy

Question 18

Pure Metals

Answer 18

In layers

Slide over each other → so they are soft

Question 19

Alloys

Answer 19

Mixture of two or more elements with at least one being a metal
Distorted layers
Cannot slide → so they are hard

Question 20

Explaining Properties of Metals

Answer 20

Negative charge between positive ions, holds the metal ions in place
Delocalised electrons enable the lattice to distort
Ductile

High melting points = electrostatic forces of attraction are in all directions so takes a lot of energy to break and melt the metal

Question 21

What are nanoparticles made from?

Answer 21

Lots of different atoms

Question 22

Risks of using nanoparticles

Answer 22

Effective as catalysts
Risk of finding their way into atmosphere
Unpredictable effects
Few health risks