Topic 2 – Bonding, Structure, and The Properties of Matter

Ionic Bonding

Between a metal and non-metal, the transfer of electrons

Metal atoms lose electrons to form positive ions (cations), while non-metal atoms gain electrons to form negative ions (anions).

The electrostatic attraction between oppositely charged ions forms an ionic bond.

Ionic compounds have high melting and boiling points due to strong electrostatic forces.

Ionic compounds

Ions form when atoms gain or lose electrons to achieve noble gas electron configurations.

Positive and negative ions attract each other to form ionic compounds with regular lattice structures.

Ionic compounds have high melting and boiling points due to strong electrostatic forces.

They conduct electricity when molten or dissolved but not as solids since ions are fixed in place.

Covalent Bonding

Between two non-metals

Atoms share electrons to create a stable electron configuration for both atoms, forming a molecule.

Examples of covalent compounds include hydrogen (H₂), oxygen (O₂), and methane (CH₄).

Covalent bonds can be single, double, or triple, depending on the number of electron pairs shared.

Giant Covalent Structures - Diamond

Each carbon atom forms four strong covalent bonds in a tetrahedral arrangement. Diamond is hard, has a high melting point, and does not conduct electricity as it has no delocalised electrons

Giant Covalent Structures - Graphite

each carbon atom forms three covalent bonds with other carbon atoms

the carbon atoms form layers of hexagonal rings

there are no covalent bonds between the layers

there is one non-bonded - or **delocalised** - electron from each atom

Particle Theory

The amount of energy needed to change state from solid to liquid and from liquid to gas depends on the strength of the forces between the particles of the substance. The larger force is needed with higher strength

Limitations of Particle Theory

Particle theory considers all particles, irrespective of their state to be small, solid, and inelastic

It doesn’t consider the difference caused by different particles, such as atoms, ions or molecules, or mixtures of all three

The theory also fails to consider the intermolecular forces that exist between different particles

Solids

Strong forces of attraction between particles, particles are packed very closely together in a fixed and regular pattern

Atoms vibrate in a fixed position but can’t change position or move

Solids have a fixed volume and shape, and a relatively high density

Solid particles have only a small amount of energy

Liquids

Particles are close together in an irregular, unfixed form

Particles can move and slide past each other which is why liquids adopt the shape of the container they are in and also why they are able to flow

Gases

Particles are in random movement and so there is no defined pattern

Particles are far apart and move quickly (around 500 m/s) in all directions, they collide with each other and with the sides of the container with force (this is how pressure is created inside a can of gas)

No fixed volume, since there is a lot of space between the particles, gases can be compressed into a much smaller volume. Gases have low density

Gaseous particles have the highest amount of energy

Aqueous

dissloved in water

Small Molecules

Small molecules are compounds made up of molecules that contain just a few atoms covalently bonded together

They have low melting and boiling points, due to the weak intermolecular forces that require little energy to overcome