Structure of an Atom What is an ATOM??? Pg 331-335

Basic parts of an atom Proton Electron Neutron Has a positive charge Has a negative charge Neutron Has neutral charge (no charge)

Atoms Most of an atom’s mass is packed into the nucleus. Parts of the Nucleus are called Nucleons Nucleons that are electrically neutral are NEUTRONS Nucleons that are electrically charged are called PROTONS. Neutrons are similar to each other, while protons are similar to each other.

Isotopes Atoms of the same element having different number of neutrons are called ISOTOPES. Ex: Hydrogen – Has 1 proton, no neutron If it has 1 proton and 1 neutron – it is called deuterium isotope If it has 1 proton and 2 neutrons – it is called tritium isotope

Isotope Examples Carbon-12 Which is an isotope of Hydrogen? Has 6 protons Has 6 neutrons Carbon-14 Has 8 neutrons Which is an isotope of Hydrogen? Protons 2 Neutrons 1 Protons 1 Neutrons 2 Protons 3 Neutrons 2 Protons 2 Neutrons 2

Atomic Number Is the number of protons in the nucleus. The number at the top in the table. Since #p = #e, the atomic number also tells us the # e in an atom Mass number The number of protons and neutrons in the nucleus Number at the bottom

Isotopes Examples Isotope # of Electrons # of Protons # of Neutrons Carbon - 12 6 ? Nitrogen-14 7 Arsenic-75 33 6 12- 6 =6 7 14- 7 = 7 33 75-33 = 42

Neutral Atom When the number of protons equal the number of electrons, we have an atom When the number of protons differs from the number of electrons we have an ION Cation - Positive ion – has lost an electron Anion - Negative ion – has gained an electron

Review Atoms – Protons (+), Electron (-), Neutron Nucleus – Protons and Neutrons only Atomic number = # of protons Isotopes – Have different # neutrons, same # of protons Ions

Using what we just learned Complete the worksheet