Electron Configuration
Electron Orbits
• Number of P+ in an atom equals the
number of e• Electrons are arranged in orbits or shells
around the nucleus
• Each orbit can only hold a certain number
of electrons. Max e- per orbit:
– Orbit 1:
2 e– Orbit 2 on: 8+, Variable
Wolfgang Pauli
Subshell
# of Orbitals
s
1
Max # of
Electrons
2
p
3
6
d
5
10
f
7
14
Shell
Subshells
Max Shell
Population
1
1s
2
2
2s 2p
8 (2 + 6)
3
3s 3p 3d
18 (2 + 6 + 10)
4
4s 4p 4d 4f
32 (2+6+10+14)
Electron Configuration
• The arrangement of electrons
– Diagram or Numbers
• Electron configuration determines how an
atom will react with other atoms.
– What it can bond with and what type of bond it
will form.
• Periodic Table Column Numbers
– Number of electrons in outer orbit
Example Problems
Review
• Write out the electron configuration for:
– Helium
– Oxygen
– Calcium
– Iron
– Iodine
– Uranium
Shells
• Electron shell = Energy Level
• Valence Shell
– Outermost energy level
Table
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Metals
Transition Elements
Poor Metals
Nonmetals
Noble Gases
Radioactivity
On-Line Periodic Table
Atomic Spectra
• The most stable state of an atom is when
electrons are at their lowest energy levels.
• Adding energy to an atom can move an electron
up to a higher energy level.
• When the atom releases energy, the electron
falls back to a stable energy level. The move
and the release of the associated energy is
emitted as light.
• Line emission spectra are like fingerprints of
elements.