The 'electronagativity' was a handwave for 'the chemical and physical properties of the element'. E.g. the solubility of its salts or other compounds in water,

The 'electronagativity' was a handwave for 'the chemical and physical properties of the element'. E.g. the solubility of its salts or other compounds in water, processes that cycle or collect it elsewhere, etc. Nitrogen is less reactive than Oxygen, doesn't form as many compounds as Carbon and has a molecule too fat to easily escape into space.