1. The Bohr Model of the Atom

2. What do we need to know? Atoms have 2 main parts
Electron cloud -- contains electrons
Nucleus – central part of the atom, contains protons and neutrons

3. Subatomic particles Symbols for each subatomic particle Electrons = e-
Protons = p+
Neutrons = n0

4. What do you need to know? Orbitals are found around the nucleus
There are 7 possible orbitals
Orbitals are determined by by looking at what period (row) the element is in
The orbitals hold a specific number of electrons (which is the same as the atomic number)

5. How many electrons per orbital?
Period 1  orbital (ring) 1: 2 e-
Period 2  orbital (ring) 1: 2 e-
orbital (ring) 2: 8 e-
Period 3  orbital (ring) 1: 2 e-
orbital (ring) 3: 8 e-
Period 4  orbital (ring) 1: 2 e-
orbital (ring) 3: 18 e-
orbital (ring) 4: 8 e-

6. Information to create a Bohr model
Atomic # = Protons and Electrons
Element name and symbol:
Magnesium (Mg)
Atomic number: 12
Atomic mass: 24
Protons: 12
Electrons: 12
Neutrons: ( ) = 12 12 Mg
24.305
Magnesium
Atomic Mass

7. Bohr model for Mg
Nucleus
12p+
12n0

8. Bohr model for Al
13p+
14n0
Ask “How many orbitals should Al have?”; “How many protons?”; “How many neutrons?”; “How many electrons in the first orbital?”; “How many electrons in the second orbital?”; “How many electrons in the third orbital?”; “What is so special about these 3 electrons?”

9. Questions??