ELECTRONS!!!
Parts of an atom
Electrons
• Negative charge
• Located outside the nucleus in an electron cloud
• They are organized into shells
• Move very quickly – impossible to see where they are
• Scientists figured out where they ‘hang out’
• Help create bonds between elements
Valence electrons are located in the outer shell or energy level.
Helium
4.00260
He
2
Total Number of electrons = 2
Valence Electrons = 2
2
Valence electrons are located in the outer shell or energy level.
Lithium
6.941
Li
3
Total Number of electrons = 3
Valence Electrons = 1
2- 1
4 & 5. Atomic mass is
the number of proton
and neutrons
Sodium
22.98977
6. 23
P: 11
N: 12
7 & 8. Atomic number =
the number of protons
Na
11
3. Valence electrons
2- 8 -1
1. Electron configuration
2. 2+8+1 = 11 total electrons
The Bohr Model – Aluminum (Al)
1. Determine the # of protons, neutrons, and electrons.
P = 13
N = 14
e- = 13 (electron configuration: 2-8-3)
The Bohr Model – Aluminum (Al)
• Draw a circle for the nucleus – fill in the number of
protons and neutrons
P+ 13
N
14
The Bohr Model – Aluminum (Al)
• Draw first energy level, draw in a maximum of 2 electrons.
P+ 13
N
14
The Bohr Model – Aluminum (Al)
• Draw second energy level, draw in a maximum of 8
electrons.
P+ 13
N
14
The Bohr Model – Aluminum (Al)
• Draw third energy level, draw in a maximum of 8
electrons.
P+ 13
N
14
Let’s Try One Together…
• Please draw the Bohr Model of Nitrogen (N)…
• Please draw the Bohr Model of Sodium (Na)…
The Lewis Structure
• Determine the amount of valence electrons using the
periodic table’s electron configuration.
• 2-8-3
• Draw a symbol for Aluminum and place the outer most
energy level of electrons around it …
Al
Let’s Try One Together…
• Please draw the Lewis Structure of Nitrogen (N)…
• Please draw the Lewis Structure of Sodium (Na)…