Define electronegativity - Leaving Cert Chemistry - Question 11 - 2019

The increase in electronegativity across the second period can be attributed to two primary factors: first, the effective nuclear charge experienced by the valence electrons increases due to a higher number of protons, leading to a greater pull on electrons; second, the atomic radius decreases, as electrons are attracted closer to the nucleus, enhancing the atom's ability to attract electrons.

In oxygen difluoride, the electronegativity values indicate that oxygen is more electronegative than fluorine, resulting in a slightly polar covalent bond. The bonding is characterized as covalent due to the sharing of electrons, with oxygen attracting the electron density slightly more than fluorine.

The shape of the OF₂ molecule is v-shaped or bent. This is because the molecule has two bond pairs and two lone pairs. The presence of lone pairs pushes the bond pairs closer together, resulting in a bent geometry.

The most probable bond angle in oxygen difluoride is 103°. This angle is preferred as it accounts for the repulsions between the bond pairs and lone pairs. The lone pairs exert greater repulsive forces, pushing the bond angles closer together than the regular 109.5° typical of tetrahedral geometry.