{title2=$\mathrm{C_{15}H_{10}O_2}$}

\b[<Flavone>] is the unsubstituted <flavonoid> parent molecule with a <phenyl group> at position2 of an oxygen-containing ring system and a <carbonyl group> at position4. Its neutral <molecular formula> is $\mathrm{C_{15}H_{10}O_2}$; its two oxygen atoms are the ring oxygen and the carbonyl oxygen. ChEBI distinguishes this specific molecule from the wider class of substituted flavones.<Flavone in ChEBI>[CHEBI:42491, definition, formula and structure; class relation CHEBI:24043]{ref}

The structural distinction matters when reading names. <3-Hydroxyflavone> has a <hydroxy group> at position3, whereas unsubstituted <flavone> does not. Adding that group by replacing a carbon-bound hydrogen adds one oxygen without changing the total hydrogen count:
$$
\mathrm{C_{15}H_{10}O_2}\longrightarrow\mathrm{C_{15}H_{10}O_3}.
$$
It changes both molecular identity and possible interactions; an alcohol suffix in a related name is not merely another spelling of the same substance.

An original <degree of unsaturation> calculation for the neutral parent gives
$$
\mathrm{DBE}=\frac{2(15)+2-10}{2}=11.
$$
Oxygen does not enter this conventional closed-shell formula count. The eleven units are consistent with two benzene-like rings contributing four each, plus a third ring, one further carbon–carbon <double bond> and the carbonyl <double bond>. The same total occurs after hydroxyl substitution, showing why this count constrains but does not uniquely determine molecular structure.

For an original amount calculation using rounded <molar mass> $222.24\,\mathrm{g\,mol^{-1}}$, a $0.100\,\mathrm{mmol}$ amount weighs $22.224\,\mathrm{mg}$. Substituted members require their own <molecular formulas> and <molar masses>.

NIST archives a <mass spectrum> and an ultraviolet/visible spectrum for the identified parent compound.<Flavone in the NIST Chemistry WebBook>[Flavone, CAS525-82-6, identity section and linked spectral records]{ref} These are complementary observations: composition, fragmentation and optical response test different aspects of a proposed chemical identity. A shared carbon framework does not supply one universal spectrum or biological effect for every <flavonoid>.


 Flavone (source code)