1. ELEMENTS, IONS AND ISOTOPES
UNIT #2 THE ATOM

2. The Subatomic Particles
Protons – positive charge (p+)
Neutrons – neutral charge (n0)
Electrons – negative charge (e-)
Protons and neutrons are found in the nucleus
Electrons are found in the electron cloud

3. Atomic Number and Atomic Mass
Atomic number is the number of protons in the atom
Atomic mass is the number of protons + neutrons
The number of protons an atom has determines which element that atom is

5. Practice
Identify the atomic number, the atomic mass and the element of the atoms below:

6. Isotopes
Atoms which have the same number of protons (have the same atomic number) but are different in the number of neutrons (have different atomic masses)

7. Ions
Atoms which are charged – have a different number of protons and electrons

8. Using Symbols to Represent Isotopes

9. Practice Isotope Atomic Number Mass Number Protons Neutrons Electrons32 16 18 50 69 46 37 48 36

10. Important Side Note
When chemists are discussing ions, they typically will not use the isotopic notation
Instead, the will just write the element symbol and the charge
Also: when the charge is +1 or -1, write just – or +