Structural formulas are a source of dread for many students, but they're an essential tool in biology lessons. A study has now shown that the stress levels of students working with chemical formulas ...

The formula H₂O shows that water is made from two atoms of hydrogen (H) bonded to one atom of oxygen (O). Katie: Time for some science. And today it's a chemistry classic, the periodic table. And here ...

Valency is the combining power of an element. Elements in the same group of the periodic table have the same valency. The valency of an element is related to how many electrons are in the outer shell.