Maximum Number of Maximum Number of ElectronsElectrons

• the formula 2nthe formula 2n22 is used to find the max. # of e- on any energy level. is used to find the max. # of e- on any energy level.

- n = the energy level = (row on P.T.)- n = the energy level = (row on P.T.)

• Ex…Ex…

• energy level 3…energy level 3… 2(3)2(3)22 = = 18 e-18 e-

• energy level 6…energy level 6… 2(6)2(6)22 = = 72 e-72 e-

Quantum numbers

• Principal Quantum Numbers• Map to determine location of the

electrons…..• (Methods for denoting e- arrangement

for an atom: orbital notation)

Quantum NumbersQuantum Numbers

• there are four quantum numbers (actually letters)... there are four quantum numbers (actually letters)...

• the ‘address’ of an e-. the ‘address’ of an e-.

11stst = = nn = energy level of the e-. = energy level of the e-.

- 1 = lowest, 7 = highest - 1 = lowest, 7 = highest

22ndnd = = ll = shape of sub-orbital= shape of sub-orbital - 4 different shapes…found on each energy level- 4 different shapes…found on each energy level

- ‘the principle quantum number’- ‘the principle quantum number’

33rdrd = = mm = orientation of orbital in space. = orientation of orbital in space.

- which axis the orbital lies on - which axis the orbital lies on

44thth = = ss = spin of the e- on its axis. = spin of the e- on its axis.

- clockwise or counter-clockwise - clockwise or counter-clockwise

- represented by rows on the periodic table- represented by rows on the periodic table

1st Quantum Number

• 1. Principal Quantum Number (n) – Describes the size and energy of an orbital

• ↑n ↑E ↑Distance from nucleus & ↓stability• Ex. n=1

22ndnd Quantum Number Quantum Number

• ll = shape of orbital= shape of orbital

• there are four orbital shapes, represented by letters…there are four orbital shapes, represented by letters…

• ss = sphere = sphere

- lowest energy- lowest energy

• each orbital can only hold each orbital can only hold 22 e-. e-.

= = 11 orbital orbital = = 22 total e- total e-

• pp = dumbbell = dumbbell = = 33 orbitals orbitals = = 66 total e- total e-

• dd = clover-leaf = clover-leaf = = 55 orbitals orbitals = = 1010 total e- total e-

• ff = double clover-leaf = double clover-leaf = = 77 orbitals orbitals = = 1414 total e- total e-

- highest energy- highest energy

2nd Quantum number cont.

• 2. Azmithual quantum number (l)- describes the subshell of the

orbital• l = n – 1• if l = 0 then the electron is in the s

subshell• l = 1 p subshell• l = 2 d subshell• l = 3 f subshell

3rd Quantum number• 3. Magnetic (ml) – describes the 3

dimensional orientation of an orbital

• Values of ml = -l to +l

• Ex. if l = 0 then ml = just one orbital

• If l = 1 then ml = 3 orbitals (-1, 0, 1 = x, y, z)

Orbitals Orbitals

‘ ‘s’ orbitals’ orbital

‘ ‘p’ orbitalsp’ orbitals

Orbitals Orbitals ‘ ‘d’ orbitalsd’ orbitals ‘ ‘f’ orbitalsf’ orbitals

4th Quantum number

• 4. Spin (ms) – describes the electron’s intrinsic magnetism

• + ½ (spin up) or – ½ (spin down)• each e- occupies the lowest energy

orbital available

SPDF blocks in periodic table

•

Quantum Numbers - Practice• What are the 4 quantum numbers

of: • The last electron in P• The 5th electron in Na• The 9th electron in Cl• The 5th electron in O• The last electron in Cu• The last electron in Fe