Polarity and Solubility, H-Bonding

Question 1

Polar Covalent bonds

Answer 1

If the electron pair in a covalent bond is not attracted equally to each atom then a POLAR covalent bond is formed. (unequal sharing of electrons between atoms)

Atoms further to the right of the periodic table generally have a stronger attraction for the shared electrons. This attraction is called electronegativity. Fluorine is the most electronengative.

e.g. in H20 oxygen is the most electron negative so the shared electrons will pull more towards it giving it a delta negative charge.

Question 2

Non-polar Covalent bonds

Answer 2

If the 2 atoms in a covalent bond are the same (e.g. H2) the bond is nonpolar since the two atoms are identical. They must share the same attraction for the shared electrons.

Equal sharing of electrons, therefore no electronegativity attraction.

Question 3

Ionic compounds, summary

Answer 3

• Solids at room temp, crystals made of ions, High melting point.
• Usually, soluble in water and insoluble in organic solvents.
• It is an electrolyte; ie the solution in water will conduct electricity

Question 4

Covalent compounds, summary

Answer 4

• Generally liquids or gases at room temp, Low melting point
• Often insoluble (non-polar) in water and soluble in organic solvents. Polar substances are soluble in water.
• If they form a solution in water it is a nonelectrolyte ie it does not conduct electricity