Atomic Structure
II. Electron Cloud Model
 Orbital
 Energy Levels
 Bohr Model Diagrams
A. Orbital
 Region where there is 90% probability of
finding an electron.
 Can’t pinpoint the
location of an
electron.
 Density of dots
represents degree
of probability.
A. Orbital
 Orbitals have different shapes.
B. Energy Levels
 Electrons can only exist at
certain energy levels.
 Low energy levels are
close to the nucleus.
 Each energy level (n) can
hold 2n2 electrons.
C. Bohr Model Diagrams
 Simplified energy levels using Bohr’s
idea of circular orbits.
Lithium
Atomic #: 3
Mass:
7
# of p:
# of e:
# of n:
3
3
4
e-
en np n
pn p
e-
Can replace with:
3p
4n
Maximum eLevel 1
Level 2
Level 3
Level 4
2e8e18e32e-
C. Bohr Model Activity
 Choose a number between 1 & 18.
 Find your element by the atomic number you picked.
 Draw a Bohr Model diagram for your element on
your marker board.
• Round off the mass listed on the table and
subtract the atomic # to find the # of neutrons.
• Abbreviate the # of ‘p’ and ‘n’ in the nucleus.
 Have a partner check your drawing.
 Repeat with a new element.