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