Learn: C3 - Structure and Bonding (TRIPLE)

Which kind of atoms form ionic bonds?

Metals with non-metals

Which kind of atoms form covalent bonds?

Non-metals

Which kind of atoms form metallic bonds?

Metals

What happens to metals in ionic bonding?

They lose electrons to form positive ions

What happens to non-metals in ionic bonding?

They gain electrons to form negative ions

What must be included on ions in dot and cross diagrams?

Square brackets and charges

How are ionic compounds held together?

By strong electrostatic forces of attraction between the oppositely charged ions

What is the structure of an ionic compound?

A lattice of alternating positive and negative ions

State three limitations of dot and cross diagrams

They show electrons in fixed positions but in reality they should be moving.

They do not show the different sizes of ions.

They only show a small number of atoms/ions.

State two limitations of ball and stick diagrams

There are no sticks between atoms in ionic lattices.

Does not show the true shape of small covalent molecules.

State one limitation of 3D diagrams of ionic lattices

They can only show a tiny fraction of the structure

What happens to electrons in ionic bonds?

They are lost by metals and gained by non-metals

What happens to electrons in covalent bonds?

They are shared

State the three types of covalent structure

Small covalent molecules, large covalent molecules (polymers and fullerenes), giant covalent structures.

Draw the dot and cross diagram for hydrogen

Draw the dot and cross diagram for chlorine

Draw the dot and cross diagram for nitrogen

Draw the dot and cross diagram for oxygen

Draw the dot and cross diagram for HCl

Draw the dot and cross diagram for water

Draw the dot and cross diagram for NH3

Draw the dot and cross diagram for CH4

Describe the structure of metals

Lattice (regular arrangement) of positive ions with a sea of delocalised electrons

What holds the structure together in metals?

Strong electrostatic forces of attraction between positive ions and delocalised electrons

Give three limitations of the particle model of solids, liquids and gases

All particles are represented as spheres.

Particles are solid but should be mostly empty space.

There are no forces between the particles.

Define boiling point

The temperature at which boiling and condensing take place

Define melting point

The temperature at which freezing and melting take place

How are melting/boiling point related to bonding?

The stronger the forces between particles, the higher the boiling and melting point.

Give the state symbol for a solid

(s)

Give the state symbol for a liquid

(l)

Give the state symbol for a gas

(g)

Give the state symbol for an aqueous solution

(aq)

Is the melting point of an ionic compound high or low and why?

High because strong electrostatic forces require a lot of energy to break

Do solid ionic compounds conduct electricity and why?

They cannot conduct because ions are fixed in a lattice so cannot move so charge cannot flow.

Do liquid or aqueous ionic compounds conduct electricity and why?

They can conduct electricity because ions are free to move so charge can flow.

Is the melting/boiling point of small covalent molecules high or low and why?

Low because there are only weak intermolecular forces which require very little energy to break. Strong covalent bonds between the atoms are not broken when it melts/boils.

How is the size of a small covalent molecule related to boiling point?

The bigger the molecule, the higher the boiling point as the weak intermolecular forces are stronger for bigger molecules.

Do small covalent molecules conduct electricity and why?

They cannot conduct because there are no charged particles. Covalent molecules do not have an overall charge.

Describe a polymer

Large covalent molecule which is a chain of monomers joined by strong covalent bonds with weak intermolecular forces between the polymer chains

Describe why metals can be bent/shaped

The layers of atoms in a metallic lattice can slide over each other

Describe why metals are good conductors of electricity

Delocalised electrons are free to move so charge can flow

Describe why metals are good conductors of heat

Delocalised electrons are free to move and transfer energy

Describe why alloys are harder than pure metals

The regular layers of atoms are distorted by atoms of different sizes in an alloy so the layers cannot slide over each other.

Describe the structure of diamond

Each carbon atom forms four strong covalent bonds to other carbon atoms

Why is the melting point of diamond high?

Strong covalent bonds require a lot of energy to break.

Can diamond conduct electricity and why?

It cannot conduct because there are no charged particles

Describe the structure of graphite

Each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings of carbon atoms. There are delocalised electrons and weak intermolecular forces between layers.

Explain why graphite and graphene conduct electricity

It has delocalised electrons which can move through the structure so charge can flow

Describe the structure of graphene

Single layer of graphite

Describe the structure of fullerenes

Large covalent molecules of carbon atoms with hollow shapes, with rings with five, six or seven carbon atoms

What is buckminsterfullerene?

C60

State two properties of carbon nanotubes

High length to diameter ratio, good conductors of electricity

State one use of graphene and carbon nanotubes

Electronics

What are nanoparticles?

Structures that are 1-100 nm in size, of the order of a few hundred atoms

State the diameter of fine particles

Between 100 and 2500 nm

State the diameter of coarse particles

Between 1 x 10-5 m and 2.5 x 10-6 m

What happens to surface area to volume ratio when the side of a cube decreases by a factor of ten?

As the side of cube decreases by a factor of 10 the surface area to volume ratio increases by a factor of 10.

Why may nanoparticles have properties different from those for the same materials in bulk?

Because of their high surface area to volume ratio.

State six uses of nanoparticles

Medicine, electronics, cosmetics, sun creams, deodorants, and as catalysts

What does "aqueous" mean?

Dissolved in water

Explain why graphite is soft and slippery

The structure has layers and there are no covalent bonds between the layers but only weak intermolecular forces, meaning the layers can slide over each other.