"Secular term"? I wasn't aware there was a religious term for it.
Nitrogen plus hydrogen is "nitrogen and hydrogen". The two can combine chemically to form ammonia (NH3) or hydrazine (N2H4). Other combinations are possible but unlikely.
Secular has nothing to do with N+H.
It's called a hydrogen bond. (There's also a vaguely similar concept called a "dipolar" or "dative" bond, but the fact that you've limited it specifically to hydrogen, oxygen, and nitrogen means that "hydrogen bond" is almost certainly the term you're looking for.)
madrigal
Temporal, lay, worldly...
The term for bacteria that convert nitrogen into nitrogen compounds is nitrogen-fixing bacteria.
The scientific term for air is "atmosphere." It is a mixture of gases that surround a planet and is composed primarily of nitrogen and oxygen.
Hydrogen (H) is not the same as the Hydrogen ion H+. H+ is the term for a hydrogen atom that has lost its electron. Since the number of electrons is not equal to the number of protons, it is called an ion. Since the hydrogen atom is comprised of one proton and one electron, the hydrogen ion H+ is simply a proton.
"Secular" is a word having to do with non-religious beliefs or practices. So the answer is "No".
secular
conversion of nitrogen gas to a usuable form
same attitude towards every religion
The term inorganic for carbon dioxide is only a conventional, historical characterization. Plus, it does not have carbon hydrogen bond.
Living organisms are made from compounds of three primary elements: hydrogen, oxygen and carbon - the last giving the term "organic chemistry" to describe now that of any carbon compound even if entirely artificial. There are also other elements in organisms, depending on the specific Biology, including nitrogen, sulphur, calcium and phosphorous, plus traces of others.