Transcript Bohr Model & Lewis Dot Diagrams

Bohr Model & Lewis Dot
Diagrams
8th Grade Physical Science
Recall...
Atom Diagrams
There are two models of the
atoms we will be using in class.
Bohr Model
Lewis Dot Structure
Bohr Model
 The Bohr Model shows all of the particles in the
atom.
 In the center are circles. Each circle represents a
single neutron or proton. Protons should have a
plus or P written on them. Neutrons should be
blank or have an N.
 In a circle around the nucleus
are the electrons.
Electrons should have a minus
sign or an e.
Facts:
 You can’t just shove all of the electrons into
the first orbit of an atom.
 Electrons orbit the nucleus in energy levels,
shells, we even call them electron clouds or
orbitals.
 Only so many electrons can be in any certain
shell.
 The electrons in the outer most shell of any
element are called valance electrons.
Row #
# of
Maximum
Elements
# of
in the Row Electrons
for that
Energy
Level
1
2
2
2
8
8
3
8
8
Valence
# of
electrons
in
outermost
shell
Atomic Structure
Try an Example!
 How to draw a Lithium atom…
 First, look at the Periodic Table of Elements
 Second, determine the number of protons
(atomic number)
 Then determine the number of neutrons
(atomic mass – atomic number)
 Then determine the number of electrons
(atomic number)
Practice:
Try the following elements on
your own:
a) H
b) O
c) Al
Lewis Dot Diagrams
The Lewis Dot Structure is a bit
different from the Bohr model.
It only shows the element
symbol and it’s outer most
electron shell.
Example:
 Step 1: Write the Element Symbol
 Step 2: Find the number of electrons in the
last energy level of the Bohr Model
(Valence Electrons)
 Step 3: Place the electrons (dots) around
the symbol in clockwise order so that there
are no more than 2 electrons per side.
 Practice: Lithium