chapter 11 · 2016. 11. 8. · isotopes: only mass is different what we “play ”with in...

Chapter 11

What subatomic particles do you get to “play” with?

Protons →

Neutrons →

Eletrons →

changes the element

isotopes: only mass is different

what we “play” with in chemistry

Bohr Model of the Atom

• electrons must circle the nucleus of an atom in certain paths

• Developed the concept of Energy Levels• Connected H’s electron with photon emission

1.e- reside in orbits2.Lowest energy closest to nucleus, increase in energy farther

from nucleus3.Empty space between each orbit4.Calculated energies of an e- in allowed energy levels; Ephoton =

h�

5.e- in higher-energy orbits, falls back to lower-energy orbit releasing a photon

6.Calculated energies agreed with line series7.Only explained H atom

Quantum Model of the Atom

Quantum (definition from Webster’s)

1) quantity, amount

2) any of the very small increments or parcels into

which many forms of energy are subdivided

Quantum Theory

-describes mathematically the wave properties of

electrons and other very small particles

*electrons were determined to have a dual wave-particle

nature

*uses two principles


Heisenberg Uncertainty Principle

-it is impossible to determine simultaneously

both the position and velocity of an electron or

any other particle

Schrodinger Wave Equation

-treats electrons as waves around the nucleus

*Together these determine the probability of finding electrons.

I. Louis de Broglie Could electrons have a dual wave-particle nature as

well?

A. e- be considered waves confined to the space around an atomic nucleus

B. e- could only exist at specific frequencies, correspond to orbit energies

C. Experiments confirmed hypothesis


Orbital

-three-dimensional region around the nucleus that

indicates the probable location of an electron

To describe orbitals, we use…..

Quantum Numbers

-specify the properties of atomic orbitals and the

properties of electrons in orbitals

*there are 4 quantum numbers


Principle Quantum Number (n)

-the main energy level occupied by the electron

*positive integers

*ranges from 1 to 7

*equals to the period

Angular Momentum Quantum Number (l)

-shape of the orbital

*orbitals possible is equal to n

*values of l are all integers less than l = n-1



l letter

0 s

1 p

2 d

3 f


Magnetic Quantum Number (m)

-indicates the orientation of an orbital around the

nucleus

* m = ±l

Spin Quantum Number

-has only 2 possible values (+½, -½)


Electron Configurations

-the arrangement of electrons in an atom

*based on 3 rules

Afbau Principle

-electrons occupy the lowest energy level they can


Pauli Exclusion Principle

-no two electrons in the same atom can have the same

set of four quantum numbers

Hund’s Rule

-orbitals of equal energy are each occupied by one

electron before any orbital is occupied by a second

electron and all electrons in singly occupied orbitals

must have the same spin


Relative Energies of Orbitals


Electron Configuration Notation

- the order of orbitals is….

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 …



Boron

5 electrons

1s2 2s2 2p1

Bromine

35 electrons

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5



Can also use Noble Gases to show Electron

Configurations since they have fulfilled the

Octet Rule

Noble Gas Notation

Bromine

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5

[Ar] 4s2 3d10 4p5


Filling Electrons using Afbau’s Principle, the Pauli

Exclusion Principle, and Hund’s Rule

Fill e- for: N

O

Al

Br


Using Quantum Numbers to Identify Elements

n l m spin

N

O

Al

Br

2 1 0 +1/2

2 0 0 +1/2

chapter 11 · 2016. 11. 8. · isotopes: only mass is different what we “play ”with in...

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