Atomic Structure and Models
Every atom contains three main particles that determine its properties. Protons have a positive charge (+1) and mass of 1, neutrons have no charge (0) but the same mass, and electrons have a negative charge (-1) with virtually no mass.
The nucleus sits at the atom's centre, containing protons and neutrons packed incredibly tightly. It's actually 10,000 times smaller than the whole atom! Electrons whizz around this tiny nucleus in the vast empty space that makes up most of an atom.
Scientists once thought atoms looked like a "plum pudding" - a cloud of positive charge with negative electrons dotted throughout like raisins in a pudding. This plum pudding model helped explain the discovery of electrons, though we now know atomic structure is more complex.
⚡ Remember: Atoms are mostly empty space - if an atom were the size of a football stadium, the nucleus would be like a marble in the centre!