1. Electron Configuration
A Closer Look at Electrons

2. Where are they in the Atoms?
Located within energy levels
Energy levels range from 1-7
Higher energy levels
The electron (e-) is farther from the nucleus
The more energy the e- has

3. Energy Level Changes
An electron absorbs energy to “jump” to a higher energy level.
When an electron falls to a lower energy level, energy is emitted.
In the visible range, the emitted energy appears as a color.
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4. Electron Energy Levels
Electrons are arranged in
specific energy levels that
are labeled n = 1, n = 2, n = 3, and so on
increase in energy as n increases
have the electrons with the lowest energy in the first energy level (n = 1) closest to the nucleus
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5. Within each energy level
There are sublevels that differ by slight differences in energy
There are four sublevels
S, P, D, F
Within each sublevel are paths called Orbitals

6. Number of Sublevels
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7. Orbitals S sublevels, there is 1 orbital, which holds a total of 2 e-
P sublevels, there are 3 orbitals, holding a total of 6 e-
D sublevels, there are 5 orbitals, holding a total of 10 e-
F sublevels, there are 7 orbitals, holding a total of 14 e-

8. Writing The e- configuration
1s2
1 = the energy level
S = the sublevel or orbital
2= the number of electrons

9. What order do orbitals fill?
Orbitals Fill in this order
Number of this type of orbital
Total # of electrons 1s 1 2 2s 2p 3 6 3s 3p 4s 3d 5 10 4p

10. How to write an e- configuration
Locate the element on the periodic table.
2. Fill the orbital in the proper order.
3. Check that the total # of e- you have equals the atomic # for that element

11. Complete filling order
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p

12. Orbitals
An orbital
is a three-dimensional space around a nucleus where an electron is most likely to be found
has a shape that represents electron density (not a path the electron follows)
can hold up to 2 electrons
contains two electrons that must spin in opposite ↑↓
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13. s Orbital's An s orbital has a spherical shape around the nucleus
increases in size around the nucleus as the energy level n value increases
is a single orbital found in each s sublevel
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14. p Orbitals A p orbital has a two-lobed shape
is one of three p orbitals that make up each p sublevel
increases in size as the value of n increases
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15. Sublevels and Orbitals
Each sublevel consists of a specific number of
orbitals.
An s sublevel contains one s orbital.
A p sublevel contains three p orbitals.
A d sublevel contains five d orbitals.
An f sublevel contains seven f orbitals.
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16. Practice problems
Write the electron configuration for the following elements
Carbon (C)
Lithium (Li)
Sodium (Na)
Chlorine (Cl)
Potassium (K)
Iron (Fe)

17. Chemistry 111/112 Chapter 9
Orbital Diagrams
An orbital diagram represents each orbital with a box, with orbital's in the same subshell in connected boxes; electrons are shown as arrows in the boxes, pointing up or down to indicate their spins.
REMEMBER:Two electrons in the same orbital must have opposite spins. ↑↓
Copyright (c) 2003 Thomson Learning Reprinted with permission 1