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Bohr described atoms as being like solar system.The electrons orbiting around the nucleus.

Schrodinger described atomic model with

electrons in three dimensions.

He described where electrons could be found interms of three coordinates:

Prinicpal quantum number – n ngular quantum number – l

!agnetic quantum number " m

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Principal #uantum number – n

$escribes the energy le%el within the atom& i.e.the shell number – '& (& )& etc

 ngular *momentum+ quantum number " l  $escribes the suble%el in the principal quantum

number 

Suble%els in the atoms are s, p, d, f • ,or s suble%el l = 0

• ,or p suble%el l - '

• ,or d suble%el l - (

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!agnetic quantum number – m

$escribes the orbital within the suble%el s has one orbital – m -

p has three orbitals – m - "'& & /' d has fi%e orbitals – m - "(& "'& & /'& /(

The fourth quantum number is the one known asthe Spin #uantum number 

This describes the spin of the electron

0lectrons in the same orbital must ha%e opposite

Possible spins are clockwise and anticlockwise

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• Shell number 

• Sub"shell

• 0nergy shift

• Spin

• n *'& (& )+

• l (0, 1, 2)

• ml(0;-1,0,1; ...)

• ms

• '& (& )

• s& p& d

• "l – l 

• "1 – 1

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n Principal #uantum number *Shellnumber – '& (& )& ...+

l  2rbital shape3angular quantumnumber *Sub"shell – s *+& p *'+ d*(++ – n"'

ml  

!agnetic quantum number *energyshift+ "l    – l   

ms

0lectron spin quantum number*electron spin "1 or 1

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n = 1 l = 0 ml  = 0 ms = -½

n = 1 l = 0 ml  = 0 ms = ½'s

(s

(p(p

4(p

y(p

5

n = 2 l = 0 ml  = 0 ms = -½

n = 2 l = 0 ml  = 0 ms = ½

n = 2 l = 1 ml  = -1 ms = -½

n = 2 l = 1 ml  = -1 ms = ½

n = 2 l = 1 ml  = 0 ms = -½

n = 2 l = 1 ml  = 0 ms = ½

n = 2 l = 1 ml  = 1 ms = -½

n = 2 l = 1 ml  = 1 ms = ½

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2rbital Shapes

 n atomic orbital can be thought of as a picturethat would be obtained if we photograph wherethe electron has been at different times

i.e. if we would plot the probability of finding anelectron at a particular distance from thenucleus in three dimensions

6t is a sort of a cloud around the nucleus

2rbitals are ) dimensional structures withcomplicated features

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The s orbitals arespherical

The p orbitals are

dumbbell shaped

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Blocks in the Periodic Table

• The periodic table is di%ided into blocks

 –  s block: ha%e %alence configuration of s' or s(

 –  p block: has %alence configuration of s( p' to s( p7

 –  d block elements ha%e %alence configuration inwhich d subshells are being filled

• 8hemically& elements in the same block show

same general characteristics• e.g. s block elements are all metals with low

electronegati%ity

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• P block elements are mi4ed – with some metalson the left& and non"metals on the right

• Between the metals and non"metals found in

the p block are the semi"metals *metalloids+• The d block elements are the transition metals