1

Chapter 11: Modern Atomic Theory or

Quantum Mechanics ROCKS!!!

I. Interaction of Light and Matter

A. Properties of Light

B. Emission of Light

C. Bohr Model of the Atom

II. Quantum Mechanical Model of the Atom

A. The Hydrogen Atom

1. Atomic Orbitals and Quantum #’s

2. Shapes of Orbitals

B. Electron Configurations of Elements

III. Atomic Properties and the Periodic Table

A. Atomic Size

B. Ionization Energy

C. Metals and Non-Metals

+

2

I. Interaction of Light and Matter

A. Properties of Light

Properties of Light (Electromagnetic Radiation)

?

http://abyss.uoregon.edu/~js/glossary/wave_particle.html

3

Terms Used to Describe Waves

1. Wavelength (λ) – distance between successive

peaks in a wave

2. Frequency (ν) – the number of wavelengths that

pass a given point per second

4

Terms Used to Describe Waves Cont’d

3. Amplitude – measure of the intensity of light

4. Energy (E)

5

Range of Wavelengths

Electromagnetic Spectrum

High Energy

gamma rays > x-rays > ultraviolet light > visible light >

Low Energy

infrared light > microwaves > radio waves

Visible Light

GAMMA RAYS HURT!

HULK THIRSTY!

HULK WANT PEPSI!

6

Chemistry with Light

UV light –

Vis light –

IR light –

Microwaves –

7

B. Emission of Light

What happens when atoms gain energy?

What happens when atoms lose energy?

8

Information from light emission

9

What is really going on?

10

C. Bohr Model of the Atom

1. Electrons move in circular orbits around the nucleus.

2. There are only certain allowed orbitals.

3. In order for an electron to move between orbitals it must

gain/lose the right magnitude of energy.

Absorption and Emission of Light from Atoms

11

II. Quantum Mechanical Model of the Atom

A. The Hydrogen Atom

De Broglie – If light is particle-like and wave-like

then perhaps all matter has both

types of properties

Electrons – have both wave-like and particle-like

properties!

Schrödinger Equation

Orbital –

3-dimensional – 3 variables

EzyxVdz

d

dy

d

dx

d

m

),,(

2 2

2

2

2

2

22

m = mass of particle

ђ = planck’s constant / 2

Me H-atom

Locations Where There is High Probability of Finding Matt

12

Orbitals

13

A Closer Look at Orbitals - All atoms have the same general pattern of “living

spaces for electrons.

14

Shape of Orbitals

1. s-orbitals

2. p-orbitals

3. d-orbitals

2p

1s 2s

3d

1s 2s 3s

15

B. Electron Configurations of Elements

Atomic Structure and the Periodic Table

a) Aufbau Principle (building up) - electrons are added to an atom starting with the

lowest energy orbitals first

b) Pauli Exclusion Principle - 2 electrons can fit in each orbital

- electrons have spin

c) Hund’s Rule - the electron configuration with the lowest energy

has the maximum number of unpaired electrons

Homes for the electron in Hydrogen

N=1

N=3

N=2

3d 3s 3p 1s 2s 2p

Homes for the electron in Helium

N=3

N=2

N=1

3d 3s 3p 1s 2s 2p

Homes for the electron in Lithium

N=3

N=2

N=1

3d 3s 3p 1s 2s 2p

Homes for the electron in Nitrogen

N=3

N=2

N=1

3d 3s 3p 1s 2s 2p

16

Electron configurations for elements

1H 1 e-

2He 2 e-

3Li 3e-

4Be 4e-

5B 5e-

1s 2s 2p

1s 2s 2p

1s 2s 2p

1s 2s 2p

1s 2s 2p

17

6C 6e-

7N 7e-

8O 8e-

9F 9e-

10Ne 10e-

11Na 11e-

3s 3p 1s 2s 2p

1s 2s 2p

1s 2s 2p

1s 2s 2p

1s 2s 2p

1s 2s 2p

H

Li Be

Na Mg

B C N O F

Al Si P S Cl

He

Ne

Ar

The Periodic Table and Electron Configurations

18

Electron Configurations (Period 3)

Period 4 and Below

The Periodic Table

19

Period 5

Period 6

Period 7

20

“Easily” Explained Exceptions

s1

s2

d1 d2 d3 d10d5d4 d7d6 d8 d9

p1p2 p3 p5p4 p6

exception Lots of exceptions

21

Sum Up (Categories of Electrons) a) Valence electrons - reactive electrons in the

outermost energy level

(highest n)

- usually the electrons in the

highest or outermost s & p

orbitals

b) Inner core electrons - unreactive lower energy level

electrons

Helpful Simplification

22

Possible Questions

What is the full electron configuration for

Calcium?

What is the abbreviated electron configuration

for Br?

What is the abbreviated electron configuration

for Zr?

How many d electrons does Mo have?

How many valence electrons does Mo have?

How many unpaired electrons?

23

III. Atomic Properties and the Periodic Table

A. Atomic Size

Down a Group

Across a Period

Comparing the electron configuration and size of Li and Na

Li Na

Comparing the electron configuration and size of Mg and Al

Mg Al

24

B. Ionization Energy

Ionization energy -

Down a Group

Across a Period

25

Formation of Binary Ionic Compounds

Metal + Non-Metal Ionic Compound

Metals

Non-metals

26

Electron Configurations and Ions

Trend - When they react to form ions, atoms lose

electrons until they have 0 valence electrons, or

they gain electrons until they have 8 valence

electrons

Magnesium

Fluorine

27

Metals with Electrons in d-orbitals

Trend - Metals tend to lose electrons from the

outermost s & p orbitlas to form ions (sometimes

d-electrons can also be lost)

28

Example Problems

Which element in group 1 most easily loses

electrons? Why? Which element in group 1

is the most reactive?

Which element in group 7 will most easily

lose electrons? Why? Which element in

group 7 is the most reactive?

Arrange each of the following elements in

order of increasing atomic size.

Sn, Xe, Rb, Sr