U1 CHEMISTRY
1.3 Bohr Diagram
AGENDA
1. Attendance
2. Starter : Game
3. Lesson : Drawing Bohr Diagrams
4. Explore: Patterns on the Periodic Table – Periods
5. Activity: Skittle Bohr Diagram
6. HW : Draw Bohr Diagrams
TOPIC: BOHR DIAGRAMS
LEARNING TARGETS
•I can apply Bohr’s model to explain that
the electrons of an atom are found in
different shells.
•I can apply Bohr’s model to draw
diagrams of atomic structure.
STARTER:
•THE EPIC PERIODIC TABLE
SCAVENGER HUNT!
THE BOHR MODEL
(shell)
BOHR DIAGRAMS:

Bohr diagrams show how many electrons appear in each electron shell around an atom.
BEFORE WE LEARN HOW
TO DRAW BOHR
DIAGRAMS…
WE NEED TO RECALL…
RECALL: ELECTRIC
CHARGE OF AN ATOM
•Atoms are electrically
neutral meaning the
number of protons is
equal to the number of
electrons.
RECALL: ATOMIC MASS
•Atomic Mass = # protons + # neutrons
•You’ll notice that the atomic mass shown
on the periodic table is NOT a whole
number.
•To calculate the number of neutrons in an
atom, you need to round the atomic mass
and subtract the atomic number.
VALENCE ELECTRONS
•Electrons at the outermost are called
valence electrons.
•The outer most energy level is also
referred to as the valence shell or orbit.
•The number of valence electrons do not
exceed 8.
•Each shell holds a maximum number of
electrons (2, 8, 8, 8)
b
12
DRAWING BOHR DIGRAMS
#P= 8
#n= 16-8=8
#e= 8
PRACTICE
Hint: They are in Group one
Neon has 8 electrons in its valence shell…
A stable octet: when there are 8 electrons in the
outermost shell. Very Stable!! Not Reactive!!
Oct = 8
TIP:
 Quick way to find the number of valence electrons?
[Except the transition elements (groups 3-12)]
last digit of the group # = # of
valence electrons
Ex:
Group 1 = 1 valence electron,
Group 13 = 3 valence electrons
RECALL: PATTERNS ON THE PERIODIC TABLE
•You will notice that groups or
families (vertical columns) all
possess the same number of
valence electrons.
•Atoms in periods (horizontal
rows) a have electrons on the
same number of energy
levels (shells).
ACTIVITY: SKITTLE BOHR DIAGRAM
HOMEWORK
Dram the Bohr diagrams of the first 20 elements.