Atoms

Atoms

1. The nucleus

   • In the middle of the attom
   • Contain protons and neutrons
   • It has a positive charge because of the potons
   • Almost the whole mass of the atom is concentrated
   • It is tiny compared to the rest of the aom

2. The electons

   • They move around the nucleus in energy levels called shells
   • They're negativly charged
   • They are tiny,but cover a lot of space
   • The size of their orbits detrmines how big the atom is
   • They virtually have no mass

3. Protons

   • Heavy
   • Positively charged

4. Neutrons

   • Heavy
   • Neutral

5. Electrons

   • Tiny
   • Negatively charged
     • Electron mass is often taken as zero
   • Number of electrons equals number of protons
     • Same size charge , but opposite
     • If some electrons are added or removed, the atom becomes charged and is then an ion

6. 23 Na 11

   • Mass number-total number of protons and neutrons
   • Atomic number- number of protons

7. Molecules are groups of Atoms

   • Atoms join together to make molecules
   • Some molecules are made from just one element, while others are made up of more than one element
   • Molecules are held together by covalent bonds