chemistry - intro to electron configurations

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electron configurations:

show how electrons are distributed within an atom

principal energy levels

n = 1,2,3,4, etc

describes the average distance of an electron from the nucleus

sublevels

correspond to the different areas an electron can be located in an atom

s, p, d, f, g, etc

energy level 1

1s

energy level 2

2s 2p

energy level 3

3s 3p 3d

energy level 4

4s 4p 4d 4f

energy level 5

5s 5p 5d 5f 5g

atomic orbitals

each sublevel is oriented differently in 3-d space, and each orientation is called an atomic orbital

s sublevel

1 orbital, 2 electrons

_

p sublevel

3 orbitals, 6 electrons

_ _ _

d sublevel

5 orbitals, 10 electrons

_ _ _ _ _

f sublevel

7 orbitals, 14 electrons

_ _ _ _ _ _ _

g sublevel

9 orbitals, 18 electrons

aufbau principle

electrons enter sublevels with the lowest energy first

pauli principle

atomic orbitals can only hold two electrons at most and they must have opposite spins

hunds rule

in a sublevel with more than one orbital, put one electron into each orbital before putting two electrons into any one orbital

isoelectronic

if two atoms have the same number of electrons they are said to be :

valence electrons

electrons located in the outermost energy level

to count the number of valence electrons you must look at the highest numbered energy level

n- principle quantum #

first #

1,2,3, etc

average distance of electrons to nucleus

the larger the value, the farther frim nucleus

l - angular momentum quantum #

shape of the orbitals (sublevels)

s=0 p=1 d=2 f=3 g=4

m l -magnetic quantum #

orientation of orbital

_ _ _

-1 0 1

ms- electron spin quantum #

tells whether up or down

+1/2 or -1/2