Electronic Structure of Atoms & Periodic Table

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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

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Quantum Numbers

Principal quantum number – ( n )

Angular momentum quantum number – ( l )

Magnetic quantum number – ( ml )

Spin quantum number – ( ms )

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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

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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)

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l = 0 (s orbitals)

l = 1 (p orbitals)

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l = 2 (d orbitals)

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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


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ml = -1 ml = 0 ml = 1

ml = -2 ml = -1 ml = 0 ml = 1 ml = 2

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spin quantum number ms

ms = +½ or -½


ms = -½ms = +½

Experimental arrangement for demo the spinning motion of electronsQ & A

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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.


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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?

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How many 2p orbitals are there in an atom?

How many electrons can be placed in the 3d subshell?

Q & A

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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

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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)

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H 1 electron H 1s1

Li 3 electrons Li 1s22s1

B 5 electrons B 1s22s22p1

C 6 electrons C 1s22s22p2

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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

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What is the electron configuration of Mg?

What are the possible quantum numbers for the last (outermost) electron in Cl?

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Outermost subshell being filled with electrons

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Paramagnetic

unpaired electrons

2p

Diamagnetic

all electrons paired

2p

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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

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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

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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

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Write electron configurations for the following atoms: a. H

b. Li+

c. N

d. F-

e. Ca

Q & A session

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Draw an orbital diagrams for atoms with the following electron configurations:

1s22s22p63s23p3

Q & A session

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Periodic Table

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When the Elements Were Discovered

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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

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Classification of the Elements

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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

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+1 +2 +3 -1-2-3

Cations and Anions Of Representative Elements

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Ion charges

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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- ?

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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

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Electronic Structure of Atoms & Periodic Table