Transcript Chapter 5 Electrons in the atom

Chapter 5 - Electrons in the Atom
The Changing Model of the Atom
Dalton
Bohr Model
Thomson – plum pudding
Rutherford - nuclear atom
de Broglie Model
Electron Cloud Model
Current atomic model - Quantum Mechanical
– Still has the nucleus containing
protons and neutrons in the center.
– Still has electrons outside the
nucleus in a low density area
– The quantum mechanical model
determines the allowed energies
an electron can have and how likely
it is to find the electron in various
locations around the nucleus.
– This model is based on equations
developed by Erwin Schrödinger
In the quantum mechanical
model, the probability of
finding an electron within a
certain volume of space
surrounding the nucleus
can be represented as a
fuzzy cloud.
The cloud is more dense
where the probability of
finding the electron is high.
5.1
The Quantum Mechanical Model
– The propeller blade has the same probability of
being anywhere in the blurry region, but you
cannot tell its location at any instant. The
electron cloud of an atom can be compared to a
spinning airplane propeller.
3 WORDS we use to describe
where the electron might be…
• Principle Energy Level
– The energy level denoted by the principal
quantum number (n)
• Sublevel
– characteristic shapes which can predict the
location of the electron
• Electron Orbitals (atomic orbitals)
– Another name for sublevels
–spd&f
Principle Energy Levels of Electrons (n)
n tells you how many sublevels can be found in that energy level
Principle Energy Level
Sublevels– orbitals
1
1 s
2
2
s p
3
3
s
p
d
4
4
s
p
d
Electron capacity
2
2+6=8
2 + 6 + 10 = 18
f
2 + 6 + 10 + 14 = 32
Sub Levels / Electron Orbitals
A region of space in where there is a high probability of finding an electron
Each Orbital can hold 2 electrons
s – orbital (1 shape)
spherical
d – orbitals (5 shapes)
double dumbbells
p – orbitals (3 shapes)
pair of lobes
f – orbitals (7 shapes)
Periodic Table – orbital organization
1. Aufbau Principle
2. Pauli Exclusion Principle
3. Hund’s Rule
The Aufbau Principle
• Aufbau is German meaning "building up, construction”
• Deals with the ground state of an atom
• An electron enters the orbital of lowest
energy first
Periodic Table – orbital organization
Pauli’s Exclusion Principle
•Each orbital can only hold 2 electrons
•If there are 2 electrons in the same orbital
they must have the opposite spin.
1s
The Electronic Configuration of Helium
H
He
1s1 _
1s2 
He: Atomic # of 2, 2 electrons in a neutral He atom
Hund’s Rule
• AKA rule of maximum multiplicity
• sublevels fill so that the number of
unpaired electrons are maximized
• In orbitals of equal energy, one
electron enters each orbital until they
each contain one electron with the
same spin
Putting it together
Electronic configuration
H
1s1
Energy Level
# of electrons present
Sublevel
Orbital Energy Level Diagram H 1s 