1. Structure of an Atom
What is an ATOM??? Pg

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

3. 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.

4. 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

5. 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

6. 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

7. 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

8. 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

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

10. Using what we just learned
Complete the worksheet