TRIPLE Structure and Bonding

What type of substance melts at a specific temperature?

A pure substance

What type of substance melts over a temperature range?

A mixture

What is a formulation?

A mixture made up in definite proportions designed to give a product the best properties for its function.

Name seven examples of formulations?

Fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods.

In paper chromatography, what is the stationary phase?

The paper

In paper chromatography, what is the mobile phase?

The solvent

In chromatography, how can you tell a substance is a mixture?

There is more than one spot

How do you calculate the Rf value in chromatography?

Distance moved by substance ÷ distance moved by solvent

Why do atoms form ions?

To obtain a full outer shell/noble gas electron structure

How do group 1 atoms form ions?

Lose 1 electron.

What is the charge on a group 1 ion?

+1

How do group 2 atoms form ions?

Lose 2 electrons

How do group 7 atoms form ions?

Gain 1 electron

What is the charge on a group 7 ion?

-1

How do group 6 atoms form ions?

Gain 2 electrons

What is the charge on a group 6 ion?

-2

In chemistry, what is a species?

A particle

What is an electrostatic force?

An attraction between positive and negative species

What is an ionic bond?

An electrostatic force between oppositely charged ions

How do ionic bonds form?

Electron(s) transferred from metal atom to non-metal atom

What is a lattice?

A regular giant 3D structure

What is the structure of ionic compounds?

A giant ionic lattice

What type of bond is formed between a metal atom and a non-metal atom?

Ionic

What happens when a substance melts?

Forces or bonds between particles are overcome

Why do different substances have different melting points?

Forces or bonds between particles may be weaker or stronger

What is the melting point of an ionic substance?

High

Give two reasons why ionic substances have a high melting point

Giant structure and strong ionic bonds

What is needed to allow a substance to conduct electricity?

Mobile charged particles

Do ionic substances conduct electricity when solid?

No

What can you do to an ionic substance to make it conduct electricity?

Melt it or dissolve it

Why don't solid ionic substances conduct electricity?

Ions are fixed in position

What feature of molten or dissolved ionic substances allow them to conduct electricity?

Ions can move

How do molten or dissolved ionic substances conduct electricity?

Mobile ions carry the charge

What is a covalent bond?

A shared pair of electrons

How do two non-metal atoms combine?

By sharing electrons

What type of atoms combine using covalent bonds?

Non metals

How does a covalent bond form?

Two non-metal atoms share electrons

Why do non-metal atoms share electrons?

To get a full outer shell/noble gas electron structure

Name two types of covalent structure

Simple molecular and giant covalent

What is a simple molecular structure?

Consists of small molecules

In a simple molecular structure what type of bond is found within the molecules?

Covalent

What is an intermolecular force?

A weak attraction between molecules

Why do atoms form ions?

To get a full outer shell/noble gas electron structure.

How do group 1 atoms form ions?

Lose 1 electron

When a simple molecular substance melts, what is overcome?

Intermolecular forces, the molecules separate from one another

What happens to covalent bonds when a simple molecular substance melts?

Nothing: the molecules separate

What is a giant covalent structure?

A regular 3D structure consisting of many non-metal atoms

Name three giant covalent structures

Diamond, graphite and silicon dioxide

Which element forms graphite and diamond?

Carbon

In graphite how many covalent bonds does each carbon atom form?

3

In diamond, how many covalent bonds does each carbon atom form?

4

Give three properties of diamond

Hard, high melting point, does not conduct electricity

Give four properties of graphite

Soft, slippery, high melting point, conducts electricity

Why does graphite conduct electricity?

Delocalised electrons carry charge through the structure

Why do diamond and graphite have high melting temperatures?

Many strong covalent bonds must be broken

Why is graphite slippery?

Layers can slide over each other

What is graphene?

A single layer of graphite

Give two properties of graphene

Conducts electricity, very strong

What is a fullerene?

Molecules of several carbon atoms with hollow shapes

What shape can fullerenes be?

Tubes or spheres

What is a nanotube?

A cylindrical fullerene

Give two properties of nanotubes

Very strong, conducts electricity

Give three uses of fullerenes

Lubricants, drug delivery, electronics

Why can spherical fullerenes be used a lubricants?

They can roll

What are nanoparticles?

Particles between 1 to 100nm in diameter

How are nanomaterials different from other materials?

MUCH higher surface area to volume ratio

Give three uses of nanoparticles

Catalysts, cosmetics, sunscreen

What are fine nanoparticles?

Particles between 100 and 2500nm in diameter

What are coarse nanoparticles?

Dust particles between 2.5-10 micrometres in diameter