Bohr Model - OCPS TeacherPress

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Transcript Bohr Model - OCPS TeacherPress

Vocabulary
• Bohr model
• Energy level (shell)
• Valence electrons
Bohr Model
• Electrons orbit the nucleus
of an atom in set energy
levels
P = 20
N = 20
Energy Level
• The specific energies an electron in an atom
can have
• In the Bohr model used to describe the
different orbits or shells that the electrons
travel in around the nucleus
Valence Electrons
• The electrons in the highest or
outermost energy level
Bohr Models are NOT Boring!
How to Draw Bohr Diagrams
Bohr models-a simple way to draw an
atom
• Bohr models are a way of showing the
electrons in an atom.
• Electrons are arranged in energy levels. In
actual atoms, those energy levels are clouds of
crazy shapes where the electrons are likely to
be found.
• Bohr models show the electron energy levels
in nice, neat, easy to draw circles.
Bohr Diagrams
1) Find the element on the periodic table.
2)Determine the number of electrons--it is the
same as the atomic number.
3)This is how many electrons you will draw.
Bohr Diagrams
1
• Find out which period
(row) your element is in.
2
3
4
5
6
7
•Elements in the 1st period
have one energy level.
•Elements in the 2nd period
have two energy levels,
and so on.
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The electron energy levels or shells surrounding
the nucleus each hold a particular number of
electrons.
Energy levels or shells are represented by n=
period number:
n=1
n=2
n=3
n=4
max 2 electrons
max 8 electrons
max 18 electrons
max 32 electrons
Remember: The outer shell of an atom (no
matter what letter) can only hold 8 electrons!
Max Electrons in each Energy Levels
2 electrons in 1st, 8 electrons in 2nd, 18 electrons in the 3rd, 32 electrons in the 4th
Things get a little crazy in the 3rd and 4th rings…8 go into the 3rd, then the
next 2 go into the 4th, then the electrons go back and fill up the 3rd
2e
P=
N=
8e
18 e
32 e
Max rule (2,8,18,32)
Fill rule (2,8,8,2 then rest in 3rd)
Bohr Diagrams
1) Draw a nucleus.
P=6
N=6
2)Write the number of
Protons and Neutrons the
element has inside the
nucleus.
Note: Round mass to nearest 1 when figuring neutrons.
Bohr Diagrams
P=6
N=6
1) Carbon is in the 2nd period,
so it has two energy levels,
or shells.
2) Draw the shells around the
nucleus.
Bohr Diagrams
1) Add the electrons.
P= 6
N=6
2) Carbon has 6 electrons.
3) The first shell can only
hold 2 electrons.
4) The second shell put the
remaining 4 electrons
Bohr Diagrams
H
P+ =
N0 =
Try Hydrogen:
Atomic Mass:
Atomic Number:
Protons:
Electrons:
Neutrons:
Shells:
Valence electrons:
Bohr Diagrams
H
P=1
N=0
Try Hydrogen:
Atomic Mass: 1.008
Atomic Number: 1
Protons: 1
Electrons: 1
Neutrons: 0
Shells: 1
Valence electrons: 1
Bohr Diagrams
Check Yourself.
P= 1
N= 0
H (1)
Bohr Diagrams
He
P=
N=
Try Helium:
Helium
Atomic Mass:
Atomic Number:
Protons:
Electrons:
Neutrons:
Shells:
Valence electrons:
Bohr Diagrams
He
P= 2
N= 2
Try Helium:
Helium
Atomic Mass: 4.003
Atomic Number: 2
Protons: 2
Electrons: 2
Neutrons: 2
Shells: 1
Valence electrons: 2
Bohr Diagrams
P= 2
N= 2
Check Yourself!
He (2)
Bohr Diagrams
O
P+=
N0=
Try Oxygen:
Atomic Mass:
Atomic Number:
Protons:
Electrons:
Neutrons:
Shells:
Valence electrons:
Bohr Diagrams
P= 8
N= 8
Try Oxygen:
Atomic Mass: 15.999
Atomic Number: 8
Protons: 8
Electrons: 8
Neutrons: 8
Shells: 2
Valence electrons: 6
Bohr Diagrams
Check Yourslef!
P= 8
N= 8
O (2,6)
Bohr Diagrams
P= 13
N= 14
Try Aluminum:
Atomic Mass: 26.982
Atomic Number: 13
Protons:13
Electrons:13
Neutrons:14
Shells:3
Valence electrons:3
Bohr Diagrams
Check Yourself!
Al (2,8,3)
P= 13
N= 14
Bohr Diagrams
P= 13
N= 14
Try Aluminum:
Atomic Mass: 26.982
Atomic Number: 13
Protons:13
Electrons:13
Neutrons:14
Shells:3
Valence electrons:3
Bohr Diagrams
P= 22
N= 26
Try Titanium (Ti) :
Atomic Mass: 47.88
Atomic Number: 22
Protons: 22
Electrons: 22
Neutrons: 26
Shells: 4
Valence electrons: 2
Bohr Diagrams
Check Yourself!
Ti (2,8,10,2)
P= 22
N= 26