# How can the same elements form different compounds?

Mar 4, 2017

Organic chemistry provides a rich and varied demonstration of this principle. Take carbon, and hydrogen, 2 single elements. An entire alkane series is available: ${C}_{n} {H}_{2 n + 2}$, from methane to tars, that is huge and widely studied.
Take the olefin series, ${C}_{n} {H}_{2 n}$, different proportions allows a different family of compounds, and many members in the family.
And we could move to inorganic chemistry. There is $O {H}_{2}$, which we would call what? And also $\text{hydrogen peroxide}$, ${H}_{2} {O}_{2}$. And we could even invoke the formal cation, ${H}_{3} {O}^{+}$. What are the proportions in each example?