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Binary covalent compounds(BNC)
Definition:Binary covalent compounds, which are pure substances that consist of two nonmetallic elements.Eg. H2O, CH4

BNCs can be recognized by their formulas, which contain symbols for only two, non-metallic elements.

Example, N2O3, is a BNC as N, nitrogen and O, oxygen are both non-metals.
The identity of an element can be indicated using the following prefixes with respect to theirsubscript;
1 - mon(o)
2 - di
3 - tri
4 - tetr(a)
5 - pent(a)
6 - hex(a)
7 - hept(a)
8 - oct(a)
9 - non(a)
10 - dec(a)

The second element is indicated by its respective root;
H - hyd
C - carb
N - nitr
P - phosph
As - arsen
O - ox
S - sulf
Se - selen
F - fluor
Cl - chlor
Br - brom
I - iod

Hence N2O3: Dinitrogen trioxide