The Development of A New Atomic Model

CH. 4 .1

The Development of A New Atomic Model

Properties of Light

Acts like a wave Electromagnetic radiation-wavelike energy traveling

through space X-Rays, ultraviolet light, infrared light, radio waves, etc

Electromagnetic Spectrum- organized list of all forms of electromagnetic radiation All forms travel 3.00 x 108 m/s in a vacuum

Wavelength Frequency

λDistance from crest

to crest(or tough to trough) of corresponding waves

SI Unit: m, cm, or nm

ν# of waves that

pass a given point in a specific time

SI Unit: Hz

Properties of Light

Photoelectric Effect

Emission of electrons from a metal when light shines on the metal

Light as a Particle

Quanta Quantum of energy is

the minimum amount of energy that can be lost or gained by an atom

E- energy, J h- Plancks Constant

6.626 x 10-34 Js v- frequency, s-1

Photon Particle of

electromagnetic radiation having zero mass and carrying a quantum energy

Ground State Excited State

Lowest energy state of an atom

Atom has a higher potential energy than it does in ground state

Gives off light Moving from excited

back to ground state

The Hydrogen-Atom Line Emission Spectrum

Line-Emission Spectrum Continuous Spectrum

Narrow beam of light, when passing through a prism

Emission of a continuous range of frequencies of electromagnetic radiation

The Hydrogen-Atom Line Emission Spectrum

Bohr’s Model of the Hydrogen Atom

Emission Electron falls to a

lower energy level Photon is emitted

Absorption Electron jumps from

lower to higher energy level

Energy must be added

CH 4 .2

The Quantum Model of the Atom

Diffraction Interference

Bending of a wave as it passes through a small object

Waves overlapDifferent areas have

Reduced energy Increased energy

Electrons as Waves

Heisenberg Principle

It is impossible to determine simultaneously both the position and the velocity of an electron of any other particle

Schrodinger Wave Equation

Quantum Theory Describes mathematically the wave properties of

electrons and other very small particles

Gives the probability of finding an electron in a given orbital 3 dimensional region around the nucleus

that indicates the probable location of an electron

Atomic Orbital's and Quantum Numbers

Quantum Number Specifies the properties of atomic orbital's and the

properties of electrons in orbital's

1st 3 Numbers Indicate main energy level, shape and orientation of

orbital4th Number

“Spin” number describes the fundamental state of the electron that occupies the orbital

Principle Quantum Number

Symbol- nIndicates main

energy level occupied by electron

Positive integers only 1,2,3, etc

As n increases, distance from nucleus increases

Electrons can have the same value Same shell

Total orbital's in a shell(main energy level n2

Atomic Orbital's and Quantum Numbers

Angular Momentum Quantum Number

Sublevels Orbital's of different

shapes exist for a given value of n

Symbol- l Indicates the shape of

the orbitalValue

n-1; can be zero or positive integers

Atomic Orbital's and Quantum Numbers

Angular Momentum Quantum Number

s orbital Spherical

p orbital Dumbbell shape

d & f orbital's More complex

n=1 S orbital

n=2 s & p orbitals

n=3 s, p, & d orbitals

n=4 s, p, d & f orbitals

Atomic Orbital's and Quantum Numbers

Magnetic Quantum Number

Symbol- mIndicates the

orientation of an orbital around the nucleus

Value Whole numbers,

including zero; -l to +l

Atomic Orbital's and Quantum Numbers

Spin Quantum Number

Only 2 Values +1/2 and -1/2

Indicates the 2 spin states of an electron in an orbital

Single Orbit Max of 2 electrons Must have opposite

spin states

Atomic Orbital's and Quantum Numbers

CH 4 .3

Electron Configuration

Electron Configuration

Arrangement of electrons in an atom

Unique for each element

Ground State Electron Configuration Lowest energy arrangement of electrons for each

element

Aufbau Principle

Electrons occupy the lowest energy orbital that can receive it

Rules for Electron Configuration

Pauli Exclusion Principle

No two electrons in the same atom can have the same set of four quantum numbers

Arrows represent different spin states

Rules for Electron Configuration

Hund’s Rule

Orbital's of equal energy are each occupies by one electron before any orbital is occupied by a second electrons

All electrons in singly occupied orbital's must have the same spin state

Rules for Electron Configuration

Orbital NotationElectron Configuration Notation

Unoccupied orbital ___

Orbital with 1 electron ___

Orbital with 2 electrons ___

Quantum # and Sublevel underneath

Eliminates lines and arrows

Uses superscripts

1s22s22p6

Representing Electron Configurations

Practice pg 113

2nd Period Elements

Highest Occupied Energy Level Electron contained main energy level with the highest

principle quantum number

Inner Shell Electrons Electrons no in the highest occupied energy level

3rd Period Elements

Shorthand Notation 1st 10 electrons in an atom have the same

configuration as NeonNoble Gas Configuration

Outer main energy level occupied by 8 electrons (most cases)

4th & 5th Period Elements

Practice pg 120

Practice pg 121

Practice pg 122