Final answer:
Sodium has metallic bonding; sodium chloride has ionic bonding; the melting point of sodium chloride is high due to strong electrostatic attractions; the melting point of sodium iodide is lower than sodium bromide due to weaker ionic bond strength.
Step-by-step explanation:
The type of bonding in the element sodium is metallic bonding. In metallic bonding, the valence electrons of metal atoms are delocalized and form a 'sea' of electrons that are free to move throughout the structure. This results in the characteristic properties of metals such as malleability and electrical conductivity.
To draw a diagram of the particles arranged in a crystal of sodium, we would represent the sodium atoms as small spheres (particles) and arrange them in a repeating pattern. In a two-dimensional diagram, we can show a minimum of six sodium particles arranged in a rectangular lattice.
The type of bonding in sodium chloride is ionic bonding. In ionic bonding, there is a transfer of electrons from one atom to another, resulting in the formation of positively charged ions (cations) and negatively charged ions (anions). These oppositely charged ions are attracted to each other, forming a lattice structure.
The melting point of sodium chloride is high because of the strong electrostatic attraction between the positive sodium ions and negative chloride ions in the crystal lattice. Breaking these strong ionic bonds requires a significant amount of energy, resulting in a high melting point.
The melting point of sodium iodide is lower than the melting point of sodium bromide because the ionic bond strength decreases as the size of the ions increases. Sodium iodide has larger ions compared to sodium bromide, which leads to weaker ionic bond strength, and hence a lower melting point.