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Home , Aufbau principle, Azimuthal quantum number, Magnetic quantum number, Principal quantum number

Topics covered in Chap 6 BUT NOT IN TEXT ORDER 6.1 The wave nature of Light 6.5 Mechanics & Atomic Orbitals 6.6 Representation of Orbitals 6.7 Many- 6.8 Electron Configurations 6.9 Electron Configurations and the ATOMIC PARTICLES

Name Charge +1 0 Electron -1 WHY ? WHY the nucleus is importantbecause nucleus is the chemical determinebehavior they How are distributed outside outside aredistributed Howelectrons Electrons Act Like Magnetics Atomic Structure

1. CENTER CORE ……….NUCLEUS Contains ( / )

2. OUTERCORE …………ELECTRONS ATOMIC SYSTEM Simular To SOLAR SYSTEM

PLANETS REVOLVE AROUND THE SUN IN ORBITS Solar System Electronic Structure of Atoms ATOMIC SYSTEM SIMULAR TO SOLAR SYSTEM

ELECTRONS REVOLVE AROUND THE NUCLEUS IN ORBITS Atomic System Model Effective Nuclear Charge

Electrons are attracted to the nucleus The attraction depends on three things 1. Magnitude of the nuclear charge 2. Distance to nucleus 3. Repulsions due to other electrons (shielding or screening effect ORBITALS & SUBORBITALS

There are 7 (SEVEN) Major ORBITALS

Check out the Periodic Table

How Many Periods in the Periodic Table ? The 7 (SEVEN) Major Levels ARE SUBDIVIDED

The SUBLEVELS Are Called S, P, D, F, G … Order of Filling The S, P, D, F, G … SUBLEVELS Are further subdivided as follows: S Only one - 1 P Three of them - 3 D Five of them - 5 F Seven of them - 7 etc What is the next number ? SHAPE of ORBITALS

• What is an Orbital ?

• What do the Orbitals look like ? Coordinate System S Orbital in 3 dimension S Orbitals

. The P orbitals are aligned along the three Cartesian coordinates ( x, y, z ) NUMBER OF ELECTRONS ACCOMMODATED IN ELECTRON SHELLS AND SUBSHELLS

ELECTRON SUBSHELLS ORBITALS NUMBER SHELL AVAILABLE AVAILABLE ELECTRONS 1 S 1 2

2 S 1 2 P 3 6

S 1 2 3 P 3 6 D 5 10 1st How MANY ELECTRONS ?

• For a NEUTRAL , the Number of ELECTRONS is equal to the (which is the number of PROTONS)

• For an , the Number of ELECTRONS is INCREASED for Anions & Decreased for Cations by Charge on ION How MANY ELECTRONS ?

H ____ H+ ____ H- ____ O ____ O- ____ O-2 ____ Fe ____ 2nd , What is the • The guides the filling order of orbitals

• Electrons fill orbitals Closest to nucleus First Aufbau Principle: Lower energy orbitals fill first. Increasing Energy Core Orbitals only 1s hold two [He] 2s 2p electrons, [Ne] 3s 3p 3d [Ar] and each 4s 4p 4d 4f [Kr] should 5s 5p 5d 5f [Xe] have 6s 6p 6d [Rn] different 7s 7p . GROUND H (1 e ) 1S 1 STATE He (2 e ) 2 1S ELECTRON 2 1 Li (3 e ) 1S 2S CONFIGURATION Be (4 e ) 1S 2 2S 2 B (5 e) 1S 2 2S 2 2P 1 C (6 e) 1S 2 2S 2 2P 2 N (7 e) 1S 2 2S 2 2P 3 O (8 e) 1S 2 2S 2 2P 4 F (9 e) 1S 2 2S 2 2P 5 Ne (10e) 1S 2 2S 2 2P 6 Condensed Electron Configuratio

Li [He] 2 s 1

Na [Ne] 3s 1 K [Ar] 4 s 1 Rb ????????? What is the last electron in Cs ? Some Anomalies

Anomalies occur because the 4 s and 3 d orbitals are very close in energy Anomalous Electron Configurations

These result from the unusual stability of half–filled and fully filled subshells. should be [Ar] 4 s 2 3 d 4 but is [Ar] 4 s 13 d 5

Copper should be [Ar] 4 s 2 3 d 9, but is [Ar] 4 s 13 d 10 Electrons in the Periodic Chart ISOElectronic

Atoms or that have the same number of electrons and therefore the same electron configuration. Which of the following are isoelectronic?

C ? Cl – Mn 2+ B – Ar Zn Fe 3+ Ge 2+ SAMPLE EXERCISE 6.8

• Electron Configurations for a • What is the characteristic electron configuration of a group of elements ? • What are valence electrons ? What is the characteristic configuration of the group 7A elements, the ?

The 1 st member of the group is fluorine F(9 e) 1S 2 2S 2 2P 5 The condensed electron configuration is F [He] 2S 2 2P 5 For chlorine, the 2 nd halogen, Cl (17 e) 1S 2 2S 2 2P 6 3S 2 3P 5 Condensed is Cl [Ne] 3s 2 3P 5 The characteristic valence electron configuration of a halogen is

ns 2np 5 where n ranges from 2 in the case of fluorine to 6 in the case of astatine. PRACTICE EXERCISE Which family of elements is characterized by an ns 2np 2 electron configuration in the outermost occupied shell?

Answer: ? Break for

Exam 2 DISCRIPTION OF ELECTRONS

1. HOW MANY ARE THERE ?

2. ELECTRON CONFIGURATION Follows AUFBAU PRINCIPLE

3. ORBITAL DIAGRAM

Follows HUND ’S RULE HUND ’S RULE

Electrons Remain UNPAIRED As Long As Possible Electrons Act Like Magnetics Therefore have direction UNPAIRED Electrons

The Most Stable Arrangement of Electrons is that with the Maximum Number of UNPAIRED Electrons, all with the SAME Spin Direction ORBITAL DIAGRAMS

1S 2S 2P 3S H ( ↑ ) ( ) ( ) ( ) ( ) ( ) He ( ↑↓ ) ( ) ( ) ( ) ( ) ( ) Li ( ↑↓ ) (↑ ) ( ) ( ) ( ) ( ) Be ( ↑↓ ) ( ↑↓ ) ( ) ( ) ( ) ( ) B ( ↑↓ ) ( ↑↓ ) (↑ )( ) ( ) ( ) C ( ↑↓ ) ( ↑↓ ) (↑ )( ↑ )( ) NOTE! N ( ↑↓ ) ( ↑↓ ) (↑ )( ↑ )(↑) NOTE! Hund’s Rule How many unpaired electrons for atomic (a) Nitrogen (b) (c) Bismuth

N(7e) 1s2 2s22p3 P (15e) 1s22s22p6 3s23p3 Bi (83e) 1s22s22p63s23p64s23d10 4p65s24d10 5p6 6s2 4ƒ 14 5d10 6p3 DISCRIPTION OF ELECTRONS

1. HOW MANY Electrons ? 2. ELECTRON Configuration Follows AUFBAU Principle 3. ORBITAL Diagram Follows HUND’s Rule 4. QUANTUM NUMBERS (FOUR) Follows PAULI Principle Symbols & Meanings

Mass number (number of protons + neutrons)

12 C  Symbol of element 6 Atomic number (number of protons) ELECTRON Configuration

Number of electrons Electron Configuration H 1 1S 1 m m s QUANTUM NUMBERS (FOUR) l n n QUANTUM QUANTUM NUMBERS NUMBERS SET SET OF FOUR AN ORBITALAN DESCRIBED IS A BY denotes the number Denotes the of electrons Principle 1 S 2 denotes the Quantum Number QUANTUM NUMBERS (Four)

n l m s n = 1, 2, 3, 4, 5, 6, or 7 l = n – 1, n – 2, …. m = - l to + l

S = + ½ or – ½ N , , n are integers integers are n The values of of values The The , quantum principal The n = 1, 2, 3, 4, 5, 6, or 7 or 6, 5, 4, 3, 2, 1, = n describes the of the orbital. the of level energy the describes NUMBER l

l = n – 1, n – 2, ….

If lll = 0 1 2 3 4 5

Orbital is s p d f g h l

000 S Only one - 1 111 P Three of them - 3 222 D Five of them - 5 333 F Seven of them - 7 , l

The second quantum number defines the shape { s, p, d, f ) of the orbital. Values of l are integers ranging from 0 to n − 1.

Value of l 0 1 2 3

Type of orbital s p d f Angular Momentum Quantum Number

If lll is Orbital is 0 s 1 p 2 d 3 f 4 g , ml

The third quantum number describes the different orbital types within a shell called subshells

ml are integers ranging from -l to + l l l. − ≤ ml ≤ l m

S 000 0

P 111 -1 0 1

D 222 -2 -1 0 1 2

F 333 -3 -2 -1 0 1 2 3 {m =- l to + l

If l = 0

m = 0

If l = 1

m = - 1 0 + 1

If l = 2

m = -2 - 1 0 + 1 +2 , ms

The fourth quantum number. The spin quantum number has only two values +1/2 and −1/2.

Quantum Numbers

H(1 e) 1s 1 (↑ ) n = 1 l = 0 m = 0 s = ½ Notation: 1 0 0 ½ Pauli Exclusion Principle

No two electrons in the same atom can have identical sets of quantum numbers. Quantum Numbers

He (2) 1s 2 (↑ ↓ ) n = 1 1 l = 0 0 m = 0 0 s = ½ - ½ Quantum Numbers

Li (3) 1s 2 2s 1 (↑↓ ) ( ↓) n = 1 1 2 l = 0 0 0 m = 0 0 0 s = ½ -½ -½ Quantum Numbers

C (6) 1s 2 2s 2 2p 2 (↑↓ ) ( ↑↓ ) ( ↑) (↑ ) ( ) n = 1 1 2 2 2 2 l = 0 0 0 0 1 1 m = 0 0 0 0 -1 0 s = ½-½ ½-½ ½ ½ Quantum Numbers

N (7) 1s 2 2s 2 2p 3 (↑↓ ) ( ↑↓ ) ( ↑) (↑ ) ( ↑ ) n = 1 1 2 2 2 2 2 l = 0 0 0 0 1 1 1 m = 0 0 0 0 -1 0 +1 s = ½-½ ½-½ ½ ½ ½ Quantum Numbers

Ne (10) 1s 2 2s 2 2p 6 (↑ ↓ ) ( ↑ ↓) (↓↑ ) (↓ ↑ ) ( ↓ ↑) n 1 1 2 2 2 2 2 2 2 2 l 0 0 0 0 1 1 1 1 1 1 m 0 0 0 0 -1 -1 0 0 +1 +1 s ½-½ ½-½ ½-½ ½-½ ½-½ Energy Promotes Electron(s) to Higher Energy Level

Light and Electromagnetic Radiation Where Does Energy Come From ? Light is a form of energy

Light exhibits properties that have characteristics of discrete particles and characteristics of waves.

Electromagnetic Radiation

Wavelength (λ) given in distance (meters)

Frequency (ν) given in reciprocal time (s –1)

speed of light

C = speed of light ( a constant) C= 3.00 x 10 8 meters / second

λ = wavelength (distance. e.g., meters )

ν = frequency (measured in reciprocal time) Electromagnetic Radiation

Wavelength x Frequency = Speed of light

λ (m) x ν (s –1) = c (m s –1) RELATIONSHIP BETWEEN C λλλ and ννν C = λλλ x ννν UNITS Solve Problems !! meters 1 = meters × sec sec Which wave has the higher frequency?

The lower wave has a longer wavelength (greater distance between peaks). The lower wave has the lower frequency, and the upper one has the higher frequency RELATIONSHIP BETWEEN C λ and ν If λ = 1000 meters (AM Radio) what is the frequency ( ννν ) of radiation ? C = λλλ x ννν meters 1 00.3 x10 8 = 1000 meters × ? sec sec

C 3.00x10 8 m / s ν = = = 3.00 x 10 5 sec 1- λ 1000 m A laser used in eye surgery to fuse detached retinas produces radiation with a wavelength of 640.0 nm. Calculate the frequency of this radiation.

8 m c 3.00x10 s 10 9 nm ν = = x λ 640 0. nm 1 m

= 4.688 × 10 14 s–1 SAMPLE EXERCISE 6.2 Calculating Frequency from Wavelength

The yellow light given off by a sodium vapor lamp used for public lighting has a wave- length of 589 nm. What is the frequency? RELATIONSHIP BETWEEN ΕΕΕ λλλ and ννν

• Ε ∝ ν (directly)

• Ε ∝ 1 / λ (inversely) Electromagnetic Radiation

The amount of energy depends on the frequency (ν ) : E = hν

Where h is a constant End

Chapter 6