1. Modern Theory of the Atom: Quantum Mechanical Model

3. Recap of Bohr Model electrons:
particles moving in circular orbits with specific speed, position, & energy
energy levels possess specific quantum of energy
electrons can move between energy levels
higher energy levels farther from nucleus
e- moving up to higher E level: electron absorbs energy
e- moving down to lower E level: electron emits light energy
ground state:
electrons located in lowest possible energy levels, closest can be to nucleus

4. DeBroglie Electron-Wave
Proposed this Idea: if light can show both particle and
wave behavior, maybe matter can too
wavelength describing electron depends on energy of electron
at certain energies, electron waves make standing waves in atom
wave does not represent path of electron

5. 2 kinds of waves Traveling Wave wave not confined to given space
travels from one location to another
interrupted by hitting
boundary or another
wave
Standing Wave
confined to given space (ends are pinned)
interference between incident & reflected waves
at certain frequencies:
certain points seem to be standing still
other points - displacement changes in regular way

6. Transverse (ocean)
Longitudinal (compressed/sound)

8. Bohr Model vs. Modern Theory
electron = particle
e- path is orbit
holds 2n2 electrons
circular path
each orbit has specific energy
can find exact position/ speed
electron = wave
e– path is orbital
holds 2 electrons
not necessarily circular
each orbit has specific energy
probable location

9. Heisenberg uncertainty principle
fundamentally impossible to know velocity & position of particle at same time
impossible to make observation without influencing system
cannot specify both position & speed of electron
can only determine probability of electron’s location in given region of space

10. Orbital – Modern Theory
orbital: term describes region where e- might be found
each orbital:
specific energy & specific shape
described by 4 parameters of wave function (like an address)
quantum numbers = n, l, m, s
structure of orbitals explain:
bonding, magnetism, atom size, crystal structure

11. n: principal quantum number
specifies atom’s principal energy levels
whole number values: 1, 2, 3, 4, …
2n2 = maximum # electrons in any principal
energy level

12. l = describes sublevels
sublevels are labelled by shape:
s, p, d, f

13. s orbitals:
spherical

14. p orbitals: dumbbell shaped

15. d orbitals: complex shapes

16. f orbitals: complex shapes too

17. Sublevels 1st principal energy level: s (1 sublevel) 2nd level:
s,p (2 sublevels)
3rd level:
s,p,d (3 sublevels)
4th level:
s,p,d,f (4 sublevels)

18. m = 3rd quantum number (orbitals)
each sublevel contains 1 or more orbitals
each orbital holds a max of 2 electrons
s has 1 orbital
p has 3 orbitals
d has 5 orbitals
f has 7 orbitals
1st PEL =s (1 sublevel) = 1 orbital (__ electrons)
2nd PEL =s,p (2 sublevels) = 4 orbitals (__ e-)
3rd PEL = s,p,d (3 sublevels) = 9 orbitals (___ e-)
4th PEL s,p,d,f (4 sublevels) = 16 orbitals (___ e-) 2 8 18 32

19. 4th quantum number = s  e- spin: 2 possible values
clockwise and counter clockwise
Illustrated by arrows with opposite directions 

20. address for each electron
4 quantum numbers
no 2 e- can
occupy the same space in atom
can have same 4 quantum numbers
therefore only 2 electrons per orbital
(Pauli exclusion principle)

21. Memorize s s p d f 1 3 5 7 2e- 6e- 10e- 14e- p d f
sublevels
# of orbitals
max # of electrons
*each orbital holds 2 e- s p d f

22. electron configurations
add e- to atoms so that e- are in lowest energy levels – most stable or ground state configuration
start with 1s, then work upward in order of increasing energy
use Aufbau rule.

23. Each box represents an orbital and holds 2 electrons
3rd principal energy level, 3 sublevels
2nd principal energy level, 2 sublevels – s & p 
1st principal energy level, 1 sublevel – s
Each box represents an orbital and holds 2 electrons

24. Aufbau Principle follow arrows 1s 2s 2p sequence of orbitals: 3s 3p 3d
1s, 2s, 2p, 3s, 3p, 4s,
3d, 4p, 5s, 4d, …
exceptions do occur:
- half-filled orbitals
have extra stability
- magic # is 8 1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f

25. 1s2
2s2 2p6
3s2 3p6 3d10
4s2 4p6 4d10 4f14
5s2 5p6 5d10 5f14
6s2 6p6 6d10
7s2 7p6 7d10 He C Mg Zn
1s2
1s22s22p2
1s22s22p63s2
1s22s22p63s23p6 4s23d10

26. He C Mg Zn 1s22s22p2 1s22s22p63s2 1s22s22p63s23p64s23d10
from these modern configurations, we can figure out Bohr Configurations
All you have to do is add up the electrons in each shell (energy level) He C Mg Zn
1s2
1 = 2 2
1s22s22p2
1 = 2 2 = 2+2
2 – 4
1s22s22p63s2
1 = 2 2 = = 2
2 – 8 – 2
1s22s22p63s23p64s23d10
1 = = = =2
2 – 8 – 18 – 2

27. Hund’s Rule most e- with same spin, so if more than one same orbital:
e- fill orbitals one at time before pairing up
1s s p4

29. How many orbitals contain e-?
Which element?
How many unpaired e-?
How many principal energy level’s occupied?
How many principal energy level’s are fully occupied?
How many sublevels contain e-?
How many sublevels full?
How many orbitals contain e-?
Boron 1 2 1
Figure UN
Title:
SAMPLE INTEGRATIVE EXERCISE | Putting Concepts Together (solution (b))
Caption:
(b) The complete orbital diagram is shown. The valence electrons are the ones in the outermost occupied shell, the 2s2 and 2p1 electrons. The 1s2 electrons constitute the core electrons, which we represent as [He] when we write the condensed electron configuration, [He]2s22p1.
Notes:
Keywords: 3 2 3