Structure of the atom

Structure of the atom

1. Atoms are the smallest particles of an element that can take part in chemical reactions

   • They are too small to see directly, but the result of many experiments allows us to understand of the atom.
     • The smallest part of an atom is at the centre and is called the nucleus
       • This isabout 20 000 times smaller that the atom itself

2. Subatomic particles- Atoms are made from three types of subatomic particle.

   • The nucleus contains protons and neutrons
     • The electrons are arranged in shells (or energy levels) at different distances from the nucleus
       • Subatomic particles have very very small masses and electrica charges. Rather than give their actual masses an charges, its more convenient to descrobe their masses and charges compared to the proton
         • These are called the particles relative mass and relative charge

3. Atoms and elements- every atom of a particular element has the same number of protons- hydrogen atom has one- helium has two

   • All atoms contain the same number of protons as electrons
     • This means they have no overall charge= neutral