1
Electronic Structure of Atoms & Periodic Table
Chapter 4
CHEMISTRY - DACS 1232Fakulti Kejuruteraan Mekanikal, UTeM
Lecturer:IMRAN SYAKIR BIN MOHAMADMOHD HAIZAL BIN MOHD HUSINNONA MERRY MERPATI MITAN
2
Quantum Numbers
Principal quantum number – ( n )
Angular momentum quantum number – ( l )
Magnetic quantum number – ( ml )
Spin quantum number – ( ms )
3
Quantum Numbers (n, l, ml, ms)
principal quantum number n
n = 1, 2, 3, 4, ….
n=1n=2
n=3
distance of e- from the nucleus
4
angular momentum quantum number l
for a given value of n, l = 0, 1, 2, 3, … n-1
n = 1, l = 0n = 2, l = 0 or 1n = 3, l = 0, 1, or 2
Shape of the “volume” of space that the e- occupies
l = 0 s orbitall = 1 p orbitall = 2 d orbitall = 3 f orbital
Quantum Numbers(n, l, ml, ms)
5
l = 0 (s orbitals)
l = 1 (p orbitals)
6
l = 2 (d orbitals)
7
magnetic quantum number ml
for a given value of l ml = -l, …., 0, …. +l
orientation of the orbital in space
for l = 0 (s orbital) ml = 0if l = 1 (p orbital), ml = -1, 0, or +1
if l = 2 (d orbital), ml = -2, -1, 0, +1, or +2
Quantum Numbers (n, l, ml, ms)
8
ml = -1 ml = 0 ml = 1
ml = -2 ml = -1 ml = 0 ml = 1 ml = 2
9
spin quantum number ms
ms = +½ or -½
Quantum Numbers (n, l, ml, ms)
ms = -½ms = +½
Experimental arrangement for demo the spinning motion of electronsQ & A
10
Existence (and energy) of electron in atom is described by its unique Quantum Numbers
Pauli exclusion principle
No two electrons in an atomcan have the same four quantum
numbers.
Quantum Numbers (n, l, ml, ms)
11
12
Quantum Numbers (n, l, ml, ms)
Shell – electrons with the same value of n
Subshell – electrons with the same values of n and l
Orbital – electrons with the same values of n, l, and ml
How many electrons can an orbital hold?
13
How many 2p orbitals are there in an atom?
How many electrons can be placed in the 3d subshell?
Q & A
14
Electron configuration is how the electrons are distributed among the various atomic orbitals in an atom.
1s1
principal quantumnumber n
angular momentumquantum number l
number of electronsin the orbital or subshell
Orbital diagram
H1s1
15
Order of orbitals (filling) in multi-electron atom
1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s
“Fill up” electrons in lowest energy orbitals (Aufbau principle)
16
H 1 electron H 1s1
Li 3 electrons Li 1s22s1
B 5 electrons B 1s22s22p1
C 6 electrons C 1s22s22p2
17
The most stable arrangement of electrons in subshells is the one with the greatest number of parallel spins (Hund’s rule).
N 7 electrons N 1s22s22p3
O 8 electrons O 1s22s22p4
F 9 electrons F 1s22s22p5
Ne 10 electrons Ne 1s22s22p6
18
What is the electron configuration of Mg?
What are the possible quantum numbers for the last (outermost) electron in Cl?
19
Outermost subshell being filled with electrons
20
Paramagnetic
unpaired electrons
2p
Diamagnetic
all electrons paired
2p
21
Name the orbital described by the following quantum numbers :
a. n = 3, l = 0b. n = 3, l = 1c. n = 3, l = 2d. n = 5, l = 0
Q & A session
22
Give the n and l values for the following orbital a. 1s b. 3s c. 2p d. 4d e. 5f
What and the possible ml values for the following types of orbital? a. s b. p c. d d. f
Q & A session
23
How many possible orbital are there for n = a. 4 b. 10
How many electrons can inhabit all of the n = 4 orbital?
Place the following orbital in order of increasing energy: 1s, 3s, 4s, 6s, 3d, 4f, 3p, 7s, 5d, 5p
Q & A session
24
Write electron configurations for the following atoms: a. H
b. Li+
c. N
d. F-
e. Ca
Q & A session
25
Draw an orbital diagrams for atoms with the following electron configurations:
1s22s22p63s23p3
Q & A session
26
Periodic Table
27
When the Elements Were Discovered
28
ns1
ns2
ns2 n
p1
ns2 n
p2
ns2 n
p3
ns2 n
p4
ns2 n
p5 ns2 n
p6
d1 d5 d104f
5f
Ground State Electron Configurations of the Elements
29
30
Classification of the Elements
31
Electron Configurations of Cations and Anions
Na [Ne]3s1 Na+ [Ne]
Ca [Ar]4s2 Ca2+ [Ar]
Al [Ne]3s23p1 Al3+ [Ne]
Atoms lose electrons so that cation has a noble-gas outer electron configuration.
H 1s1 H- 1s2 or [He]
F 1s22s22p5 F- 1s22s22p6 or [Ne]
O 1s22s22p4 O2- 1s22s22p6 or [Ne]
N 1s22s22p3 N3- 1s22s22p6 or [Ne]
Atoms gain electrons so that anion has a noble-gas outer electron configuration.
Of Representative Elements
32
+1 +2 +3 -1-2-3
Cations and Anions Of Representative Elements
33
Ion charges
34
Na+: [Ne] Al3+: [Ne] F-: 1s22s22p6 or [Ne]
O2-: 1s22s22p6 or [Ne] N3-: 1s22s22p6 or [Ne]
Na+, Al3+, F-, O2-, and N3- are all isoelectronic with Ne
What neutral atom is isoelectronic with H- ?
35
Electron Configurations of Cations of Transition Metals
When a cation is formed from an atom of a transition metal, electrons are always removed first from the ns orbital and then from the (n – 1)d orbitals.
Fe: [Ar]4s23d6
Fe2+: [Ar]4s03d6 or [Ar]3d6
Fe3+: [Ar]4s03d5 or [Ar]3d5
Mn: [Ar]4s23d5
Mn2+: [Ar]4s03d5 or [Ar]3d5