Chemical bonding

What are the types of bonding

• ionic

• Covalent

• Metallic

What is ionic bonding

This takes places when metals and non metals react by transferring electrons.

What are covalent bonds

This is when non metals share pairs of electrons between each other

What is an ion

This is an electrically charged atom made by the loss or gain or electrons

What are anions

These are negative ions that form when atoms gain electrons

What are cations

These are positive ions formed when atoms lose electrons

Describe dot and cross diagrams

• useful for illustrating transfer of electrons

• Indicates the atoms where bonding electrons come from

• Fails to Illustrate the 3D arrangements of atoms and electron shells

• Does not indicate relative size of atoms

Describe ball and stick model

• useful for showing 3D arrangements of atoms

• Useful for showing the shape of a molecule

• Fails at showing movement of electrons

• The atoms are placed far apart which is not the case which in reality is not the case as the gaps between atoms are much smaller

Describe 2D representations of molecules

• shows how atoms are in a molecule and how they are connected

• Fails to show the relative sizes of atoms and bonds

• Doesn’t show the shape of a molecule

Describe solids

• particles are in regular arrangement

• Particles vibrate about a fixed position

• Particles are very close

Describe liquids

• particles are randomly arranged

• Particles move around each other

• Particles are close

Describe gases

• particles are randomly arranged

• Particles move quickly in all directions

• Particles are far apart

What is the different between boiling and evaporation

In boiling heat causes bubbles of gas to form inside the liquid allowing for liquid particles to escape from the surface and within the liquid boiling happens at a specific temperature while evaporation occurs only at the surface of the liquid where high energy particles can escape from the liquids surface at low temperatures and it occurs at a range of temperatures

What is the particle theory

This explains how matter changes state depending on the energy and forces present between the particles in the substance

What happens when a solid is heated

• the particles absorb heat which is converted to KE

• The particles vibrate more as temperature increases they vibrate so much that the solid expands until the bonds break and the solid melts

• As heating continues the now liquid substance expands more and some particles at the surface gain sufficient energy to overcome intermolecular forces and evaporate

• When the boiling point is reached all the particles gain enough energy for the intermolecular forces to break and the molecules yo escape as the liquid boils

What are the limitations of particle theory

• the theory fails to consider intermolecular forces that exist between different particles in different particles

• It does not consider the shape and size of particles

• It does not consider the space between particles

What are the properties of ionic compounds

• high melting and boiling points due to strong electrostatic forces between oppositely charged ions in all directions

• Conduct electricity when in molten form

• Brittle

When do ionic compounds conduct electricity and why

Liquids. Because when in solid state the ions are in fixed positions in the lattice and therefore unable to move and carry charge but when the ionic compounds are molten they are free to move and carry charge

What are the types of bonds between substances made up do small molecules

• covalent bonds : found between atoms

• Intermolecular forces : found between molecules

What is a polymer

They are made by linking together large number of smaller molecules called molecules

What are giant covalent structures

These are solids with high melting points because they have strong covalent bonds between atoms

What are alloys

This is a mixture of two or more metals or metal with a non metal such as carbon

What are the properties of alloys

• they can be stronger or harder than metals

• They are resistant to corrosion or extreme temperatures

Why are alloys harder than pure metals

Alloys contain atoms of different sizes so the layers become distorted this makes it difficult for atoms to slide over each other

How do metals conduct electricity

Metal atoms lose electrons to become positively ions the electrons become delocalised. Metals can conduct electricity because the delocalosed electrons are able to move through the structure and carry charge

What is a mettalic bond

This is the strong force of attraction between positive metal ions and delocalised electrons

What are allotropes

These are different forms of the same element in the same physical state

What are the allotropes of carbon

• diamond

• Graphite

• Graphene

• Fullerenes

What are the features of diamond

• they can’t conduct electricity

• They are hard and dense

• They have high boiling points

What are the properties of graphite

• Can conduct electricity

• High melting point

• Slippery

• Can be used to make inert electrodes for electrolysis

Why is graphite slippery

Graphite is arranged in layers although the atoms within the layers have strong covalent bonds between them the layers have weak intermolecular forces between them as a result the layers slide over each other

What are the properties of graphene

• it is extremely strong but also very light

• It conducts heat and electricity

• It is transparent

• It is flexible

Why is graphene so strong

This is due to its unbroken pattern and strong covalent bonds between the carbon atoms

What are fullerenes

These are a group of carbon allotropes which consists of molecules that form hollow tubes or spheres

What was the first fullerene discovered

Buckminsterfullerene spherical or ball shaped

Whar are carbon nanotubes

These are created when graphene is rolled into a cylinder

How can particles be categorized according to diameter

• coarse

• Fine

• Nano particles

What are nano particles

These are particles between 1-100 nanometers in size

What are the uses of nano particles

• they are used as catalysts due to high surface area to volume ration

• Titanium dioxide is used in sunscreen as it blocks UV light

• Silver nanoparticle are sprayed on medical clothing which gives them flexibility and the antibacterial properties of silver metal

• Silver nano particles act as built in deodorant for clothing