There are 118 elements in the periodic table, each with a unique symbol and atomic number. Symbol: A one or two-letter abbreviation used to represent the element. Atomic number: The number of ...

The numbers of subatomic particles in an atom can be calculated from its atomic number and mass number. The periodic table - AQA Mendeleev made an early periodic table. In the modern periodic ...

Atomic structure - AQA Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells. The number of subatomic particles in an atom can be calculated from the atom's ...