# How does the number of valence electrons vary with atomic number?

The number of valence electrons increases sequentially with $Z$.
Read all the answers in this [thread.](https://socratic.org/questions/what-kind-of-charge-does-oxygen-have174826) The identity of an element depends on Z#, the atomic number, which is the number of positively charged particles in the element's nucleus.
However, if there are $Z$ positive charges, in the NEUTRAL atom, there must necessarily be $Z$ negative charges, supplied by $Z$ electrons, all whizzing about the nucleus. Conservation of charge is a fundamental principle of Chemistry (and Physics).