Transcript Diagramming Atoms

Diagramming Atoms
Labeling Electrons – Part 1
Supplement to Book – Glencoe: Chapter 22 and 19-3
First a bit of Review!
• Atomic number – number of protons in
the nucleus of an atom
• Mass number – number of protons +
number of neutrons in the nucleus of an
atom
Atomic Diagrams
• Electron shell diagrams are ways to
visualize the arrangement of electrons in
an atom
• These diagrams
show which energy
levels, called shells,
the electrons are
found.
Electron shell diagrams
Particle locations
1. Nucleus
- All protons (p+)
are found in
the nucleus
- All neutrons (N)
are found in
the nucleus
Electron shell diagrams
2. Electron Cloud
- The general space around an atom
where the electrons are found
- All electrons (e-)
are found in the
electron clouds
in orbitals
Electron shell diagrams
3. Neutral atoms of any element have
equal numbers of protons and electrons
4. The number of neutrons can be found
from the atomic mass of an element
- Round atomic mass to the nearest whole number
 mass number
- Mass number = Atomic number + neutron number
Energy levels in atoms
Quantum Numbers – values which
represent the theoretical “address” of
an electron in an atom
1. Electrons are modeled in atoms
combining two atomic models
Bohr’s Model
• Electrons
orbit the
nucleus
in fixed
paths
Modern Atomic Model
• Electrons
are found
in areas
called
electron
clouds
Energy levels in atoms
2. There are distinct energy levels in an atom 
“n” number (this is the first quantum number)
• Energy levels – specific regions of space in
which electrons can move about the
nucleus of an atom, based on stability of the
atom
Energy Level Number
a. “n” can equal
1, 2, 3, 4, 5, 6, or 7
b. Only whole,
n=1
non-negative
numbers
c. Like the rungs
of a ladder
n=2
*There is nothing
n=3
between the energy levels but open space
Energy levels in atoms
3. Energy level numbers generally
correspond to period number (there is a
pattern to it)
Energy levels in atoms
4. Each energy level may contain only a
specific maximum number of electrons
n#
1
2
3
4
5
6
7
Max
e-
2
8
18
32
32
32
32
Energy levels in atoms
5. Energy levels fill
up in a specific
order
 lowest
energy (n = 1)
(most stable)
to
highest energy (n = 7)
(least stable)