Bohr Models and Lewis Dot Structures
Atoms **• Basic unit of matter• Consists of: Electrons, Protons, & Neutrons
+1
+2 +3 +/-4 -3 -2 -1
0
-5
Periodic Table of Elements
= element charges = Valence Electrons
I
II III IV V VI VII
VIII
Element• a pure chemical substance consisting of one type of atom
Atomic Number= Number of Protons = Number of Electrons
Symbol
Name
Mass Number = Number of Protons + Number of Neutrons
Bohr Models
• Proposed by Niels Bohr in 1915• Electrons orbit the nucleus in orbits that have a
set size and energy. • The energy of the orbit is related to its size. • The lowest energy is found in the smallest orbit.
Energy Levels
• When two atoms approach each other, the nuclei do not touch
• Only Electrons are involved in Chemical Reactions
• Electrons feel each other first • MOST IMPORTANT particle for bonding!
• WATCH THIS!
Bohr Models **
• Show just electrons with energy levels• 1st level holds 2• 2nd holds 8• 3rd holds 18 but is stable at 8• 4th holds 32 but is stable at 8
Try Some
• Carbon– Number of p/n/e– Draw Bohr Model
Try Some• Nitrogen
– Number of p/n/e– Draw Bohr Model
– Try some from Worksheet!!!!
Valence Electrons• Electrons that are found on the outer most
energy level. This determines the elements chemical properties
How to draw a Bohr Model?
Lewis Dot Structures• Show only valence electrons • Show only those electrons on outer energy
level