HSC CHEMISTRY 2015​.

Bonding of O2 and O3

Properties:

Both O2 and O3 are covalent molecular substances thus have low melting and boiling points due to the weak intermolecular bonds between molecules, additionally due to being covalent molecular they are commonly gas thus have a low density. However O3 has a slightly higher melting, boiling point and density.

O2 is a non-polar molecule, as both atoms have equal electronegativity, thus is insoluble in water due to their different polarities and has weak dispersion intermolecular bonds. Conversely O3 has a slight dipole due to an uneven electron distribution. While the central O∙ atom shares electrons with two other atoms, the outer atoms only share electrons with one other atom, making the central atom δ+ and the outer atoms δ-.

Due to its polar nature O3 is soluble in water, as like dissolves like, and its intermolecular bonds are dipole-dipole bonds which are stronger than O2’s weak dispersion bonds increasing its melting and boiling points. In addition to this O3 has more atoms thus is heavier meaning it has a higher density and requires more energy to vibrate the particles and heat up.

Reactivity:

When an O2 molecule reacts the double bond between atoms has to be broken. Ie. C + O2 --> CO2, the O2 has to be split so the C can go inbetween. On the other hand when O3 molecules react the generally only split off one O∙ atom, resulting in a free radical and a stable O2 molecule. This require much less energy than breaking a double bond.