The oxides of elements in period 3

Question 1

What do the metal oxides form? What properties does this give them?

Answer 1

• giant ionic lattice
  
  • bonding extends throughout the compound
• results in high melting points

Question 2

How is aluminium oxide different?

Answer 2

• ionic but with some covalent character
• aluminium forms a very small ions with a large positive charge
• therefore it can approach closely to the O^2- ion and distort its electron cloud
• so it has some added covalent character

Question 3

How can the ionic character of a bond be predicted?

Answer 3

• difference in electronegativities
• the bigger the difference, the greater the ionic character

Question 4

Why does silicon oxide have a large melting point?

Answer 4

• forms a giant covalent (macromolecular) structure
• the bonding extends throughout the giant structure, but this time it is covalent
• high MP because many strong covalent bonds must be broken to melt it

Question 5

Why do phosphorus and sulfur oxides have low boiling points?

Answer 5

• exist as seperate covalently bonded molecule
• phosphorus oxides aer solid,
  
  • weak vdW and dipole-dipole
• sulfur oxides are gases

Question 6

Why does P₄O₁₀ have a larger boiling point than sulfur oxides?

Answer 6

• larger the molecular, the greater the intermolecular forces

Question 7

What does a large difference in electronegativity?

Answer 7

ionic character