2. Bonding, Structure and The Properties of Matter

1. Solid to Liquid

2. Liquid to Solid

3. Liquid to Gas

4. Gas to Liquid

5. Solid to Gas

6. Gas to Solid

1. Melting

2. Freezing

3. Evaporation

4. Condensation

5. Sublimation

6. Deposition

Changes of state are..

physical changes because no new

substances are formed

Solids

Particles have low energy

Particles held in fixed position by forces

Particles vibrate but cannot move freely so solids keep their own shape / do not flow

Particles are close together so solids cannot be compressed

Liquids

Particles have more energy and move quite fast
Particles move freely so liquids flow

Particles are close together so liquids cannot be compressed

Gases

Particles have high energy so move very randomly

Very weak forces between particles so particles are far apart.

This means:
-gases can be compressed

-gases expand in all directions to fill their containers

Limitations of Particle Model

• Particles are shown as solid spheres

• It does not show weak forces between particles

• It does not show movement/speed of particles 

Bulk Properties

• ‘Bulk’ means the whole substance (all particles together)

Melting & boiling points and density are ‘bulk properties’ because they depend upon how all particles behave together

Ionic bonding

-attraction between oppositely charged ions

-occurs between metals and non-metals (name or formula of a compound has metal & non-metal = ionic)

Ionic bonding occurs because

metal atoms lose outer electrons to form + ions

non-metal atoms gain outer electrons to form - ions

the oppositely charged ions strongly attract each other

Ionic Charges - group:

1, 2, 3, 5, 6, 7

1. +1, Transfer/lose 1 electron

2. +2, Transfer/lose 2 electron

3. +3, Transfer/lose 3 electron

5. -3, Accept/gain 3 electrons

6. -2, Accept/gain 2 electrons

7. -1, Accept/gain 1 electrons

Example of ionic bonding question

Ca transfers 2 outer e to form Ca 2+

2 Cl each gain 1 e to form Cl -

Ca 2+ & Cl - ions strongly attract each other

Zn is…

+2

To work out the state (solid, liquid or gas) at room temperature,

compare room temperature

with each mpt & bpt:

-if room temperature is below mpt AND bpt: it has not even melted = solid

-if room temperature is between mpt & bpt: it has melted but not yet boiled = liquid

-if room temperature is above mpt AND bpt: it has melted and boiled = gas

Limitations of Ionic Models

2D Model: It only shows 1 layer of ions/does not show where the

other ions are
3-D model: It is not to scale/large gaps between ions

Dot & cross diagrams: Do not show the structure of the compound/how the ions are arranged

Predict Ionic formulae

This diagram has the same number of grey + (Li) & green – (iodine, I)

For every 1 x Li there is 1 x I

The formula is LiI

Structure of Metals

a giant lattice of positive metal ions

attracted to free (delocalised) electrons

Why can metals be Bent/shaped/stretched

into wires why are they soft?

metal atoms/ions are same size

layers are not distorted

layers slide

Why can metals conduct heat?

free (delocalised) electrons

move & transfer energy

through the structure

Why can metals conduct electricity?

Delocalised/free electrons

move & carry charge

through the structure

Why do metals have a high mpt/bpt?

giant lattice

lot of energy needed to break

strong metallic bonds

Pure metals are very soft/malleable (easily shaped) because:

atoms are the same size

layers not distorted

and can slide over each other

Pure metals have limited uses because…

-they aren’t strong (soft)

-Metals are made into alloys to make them harder and stronger

Alloys are…

mixtures of metals or a mixture of a metal & non-metal

eg carbon

Alloys are examples of a formulation because…

they are a mixture

designed as a useful product

Alloys are stronger than pure metals because:

other atoms are different size to original metal atoms

so layers of metal atoms are distorted

and cannot slide over each other

Why do molecules have low mpts and bpts?

simple molecules

little energy needed to break

weak intermolecular forces

Why do molecules not conduct

electricity?

no free electrons

to carry charge

through the structure

Diamond and Graphite are both

allotropes of carbon (different pure forms of the same element)

Diamond - description of structure

giant lattice of C atoms

each bonded to 4 others

by covalent bonds

Why does diamond have a High mpt?

giant lattice

lot of energy needed to break

strong covalent bonds

Why is diamond hard?

each C atom bonded to 4 others

by strong covalent bonds

atoms cannot move

Why does diamond NOT conduct electricity?

no free (delocalised) electrons

to carry charge through the structure

Uses of diamond (related to properties)

Drill bits (very hard, high mpt)

Cutting other diamonds (very hard)

Graphite - Description of

structure

giant lattice of C atoms

each bonded to 3 others

by covalent bonds

weak forces between hexagon layers

Why does graphite have a high mpt?

giant lattice

lot of energy needed to break

strong covalent bonds

Why is graphite soft?

weak forces between layers

so layers slide

Why does graphite conduct electricity?

Delocalised/free electrons

move & carry charge

through the structure

Graphite Uses (related

to properties)

Pencil “lead” (soft)

Lubricating machinery (slippery)

Electric motor contacts (conducts electricity)

What are fullerenes?

Hollow molecules of C atoms mainly arranged in hexagons (but

some include rings with 5 or 7 C atoms)

1st fullerene discovered:

Buckminsterfullerene (‘Buckyball’)

‘Buckyball’ contains…

60 C atoms covalently bonded into a

sphere of hexagons & pentagons

Why does Buckminsterfullerene have a low mpt/ bpt?

molecular structure/simple molecules

little energy needed to break

weak intermolecular forces

Why is Buckminsterfullerene slippery?

spherical shape

weak intermolecular forces

molecules can slide/roll

Why does Buckminsterfullerene conduct electricity?

Delocalised/free electrons

move & carry charge

through the structure

Carbon nanotubes are…

fullerenes in cylinder form

Why do Carbon Nanotubes have Relatively high mpt/bpt?

large molecules

lot of energy needed to break

strong covalent bonds

Why do carbon nanotubes resist stretching?

very long compared to their width

Uses of fullerenes

delivering drugs around the body (as they are hollow)

catalysts

strengthening other materials (as they do not break when

stretched)

electrical circuits

Surface Area to Volume Ratio

Surface Area / Volume

Energy Change

Bond breaking - Bond making

(Left - right)

Bond breaking (LHS) is..

endothermic (absorbs heat energy)

Bond making (RHS) is..

exothermic (gives out heat energy)

If overall energy change is negative

Exothermic

If overall energy change is positive

Endothermic

In terms of bonds, endothermic and exothermic reaction

Exothermic: Energy given out making new bonds > Energy needed (used) to make bonds

Endothermic: Energy given out making new bonds < Energy needed (used) to make bonds

Overall Exothermic

Overall Endothermic

Molecule size

molecules get larger

the weak intermolecular forces are stronger

more energy needed to break them

Examples of molecule size

group 7 mpt/bpt increase down the group

organic molecules getting longer

very long polymers compared to small molecules

What does this show

atoms losing and gaining an electron to form ions with all electrons shown

What does this show

atoms losing and gaining an electron to form ions with only outer electrons shown.

Describing what happens in ionic bonding

-’who’ transferred electrons

-the charge it now has (periodic table!)

-’who’ gained electrons & how many

-what charge it now has (periodic table!)
-a reference to ‘oppositely charged ions strongly attract’

Describing what happens in ionic bonding EXAMPLE

Na transfers 1 outer electron to form Na^+
Cl gains 1 electron to form Cl^-
Na^+ & Cl^- strongly attract each other

Describe the ionic bond

Mg transfers 2 outer electrons to form Mg²+
O gains 2 electrons to form O²-
Mg²+ & O²- ions strongly attract each other.

Describe the ionic bond

Ca transfers 2 outer electrons to form Ca²+

2 Cl each gain 1 electron to form Cl^-

Ca²+ & Cl^- ions strongly attract eachother

Ion charges: Group 1-3

-Group 1-3 elements (metals) transfer/lose electrons
-Their outer shells are now full like group 0 elements

-They are now positive ions because they have less electrons than protons

Ion charges: Group 6 & 7

-Group 6 & 7 elements (non-metals) accept/gain electrons

-Their outer shells are now full like group 0 elements

-They are now negative ions because they have more electrons than protons

For transition elements ion charge

Roman numeral in compound

Ions to know:

1. Cu²+

2. Fe²+

3. Fe³+

4. Ag^+

5. Zn²+

1. Copper (II)

2. Iron (II)

3. Iron (III)

4. Silver (I) or just silver

5. No Romans: +2

Molecular ions: Name charge and name of ion in compound:

1. NO3

2. OH

3. SO4

4. CO3

5. NH4

1. - nitrate

2. - hydroxide

3. -2 sulphate

4. -2 carbonate

5. + ammonium

Ionic compound formula is correct

if + and - charges cancel

Elements in compounds exist as a

structure

In all ionic compounds..

ions are arranged in a giant lattice

oppositely charged ions are held by strong electrostatic forces of attraction

since structure is 3D, forces act in every direction

Physical properties of ionic compounds

1. High melting point: Giant lattice, lots of energy needed to break strong forces of attraction between oppositely charged ions

2. Conducts electricity when melted or dissolved (solution): Ions not held in giant lattice so free to carry charge

   Does not conduct electricity when solid: Ions held in giant lattice, not free to carry charge through the structure

How to recognise an ionic compound

-Melting points only give structure of a substance: high melting point = a giant lattice

-To tell if compounds are ionic/made of ions/have ionic bonding:

metal & non-metal in the names/formula eg NaF

conduct electricity only when melted or dissolved but not when solid

Limitations of ionic models

2-D model: only shows 1 later of ions/ doesn’t show where other ions are

3-D model: not to scale and large gaps between ions

Molecular ions need brackets if

there are 2 or 3 of that ion in a formula

Molecular Ions: Do the charges match + Formula of compound examples

1. Na+ & NO3-

2. Li+ & SO4-2

3. Mg²+ & NO3-

4. NH4+ & CO3-²

1. Yes - NaNO3

2. No. Need an extra Li - Li2SO4

3. No. We need an extra NO3 - Mg(NO3)2

4. No. We need extra NH4+ - (NH4)2CO3

To predict ionic formulae with a diagram…

Count & compare how many of one element compared to another

Grey = Iodine

Green = Lithium

Same number of Grey + (Li) and Green - (I)

For every 1 x Li there is 1 x I

So formula is just LiI

Predict ionic formulae
Grey = O

Black = Ti

Twice as many grey dots (O) as black dots (Ti)

1x Ti, 2 x O

TiO2

Structure of a metal

Metallic Bonding

the attraction between positive metal ions and free (delocalised) electrons

occurs in metallic elements and alloys

delocalised electrons free to move through structure, shared through structure so metallic bonds are strong

To describe the structure of any metal

a giant lattice of positive metal ions

attracted to free (delocalised) electrons

Properties of metals

1. Bent/shaped/stretched into wires/soft: metal atoms/ions are same size, layers are not distorted, layers slide

2. Conduct heat: delocalised electrons carry energy THROUGH THE STRUCTURE

3. Conduct electricity: delocalised electrons carry charge THROUGH THE STRUCTURE

4. High melting and boiling point: Giant lattice, lot of energy needed to break, strong metallic bonds

Limitations of covalent models

Dot and Cross - do not show shape of molecule/not 3 dimensional/ only 2 dimensional

Ball & stick - not to scale; doesn’t show electrons

Displayed formula - does not show shape of molecule/not 3d/ only 2d

Most molecules

are gases at room temperature (oxygen, nitrogen), some are liquid (water) & a few are solid (sulphur) but all have low/very low mpts and bpts

Physical properties of molecules

1. Low melting and boiling point - simple molecules, little energy needed to break, weak intermolecular forces

2. Do not conduct electricity - no free electrons, to carry charge, through the structure

Pure metals are very soft/malleable

atoms are the same size

layers not distorted

can slide over eachother

Pure metals have limited uses because

they are not strong (soft) eg they cannot be used in construction

Metals are made into alloys to…

make them stronger and harder

Alloys

mixtures of metals or a mixture of a metal & non-metal eg carbon

Alloys are examples of

a formulation because they are a mixture designed as a useful product

Alloys are stronger than pure metals because

other atoms are different size to original metal atoms

so layers of metal atoms are distorted

and cannot slide over each other.

Graphite - Description of structure

giant lattice of C atoms

each bonded to 3 others

by covalent bonds

weak forces between hexagon layers

Graphite - High Mpt

giant lattice

lot of energy needed to break

strong covalent bonds

Graphite - soft

weak forces between layers

so layers slide

Graphite - Conducts electricity

Delocalised/free electrons

move & carry charge

through the structure

Graphite - Uses (related to properties)

Pencil “lead” (soft)

Lubricating machinery (slippery)

Electric motor contacts (conducts electricity)

Graphene - High mpt/bpt (like

graphite)

giant lattice

lot of energy needed to break

strong covalent bonds