A LEVEL Chemistry structure and bonding

• ionic compounds are always solid at room temperature. They have giant structures and therefore high melting and boiling points.

  ionic compounds conduct electricity when molten or aqueous due to delocalised ions that can carry charge

  ionic compounds are brittle and shatter when given a sharp blow as they form a lattice of alternating positive and negative ions so produce contact force between ions with like charges
• covalent molecules have low melting and boiling points as the forces between molecules are weak intermolecular forces.
• Electronegativity is the power of an atom to attract electrons towards itself in a covalent bond.
• The scale of electronegativity ranges from 0.7 - 4, with the higher number indicating a more electronegative element.
• electronegativity Decreases down a group in the periodic table as there is an increase in atomic radius and more shielding
• Increase along a period in the periodic table results in a decrease in atomic radius and an increase in nuclear charge, which can lead to an increase in electronegativity.
• The first 4 highest elements on the scale of electronegativity are FONCL: F, O, N, Cl.
• Halogens have high electronegativity values.
• Electronegativity is affected by three factors: nuclear charge, atomic radius, and shielding.
• Nuclear charge, which is more protons, results in a stronger attraction between the nucleus and the bonding pair of electrons.
• Atomic radius, which is closer to the nucleus, also results in a stronger attraction between the nucleus and the bonding pair of electrons.
• Shielding, which is the number of shells of electrons between the nucleus and the electrons, results in less shielding and a stronger attraction between the nucleus and the bonding pair of electrons.