Download Quantum Theory of the Atom

Models of the Atom
Lets Review!

Orbitals

Ground vs Excited state

Electromagnetic spectrum

Photons and waves

Flame test

Atomic Emission Spectrum

Spectroscope
2
2
l. Models of the Atom
A.
There were many different models over time
1.
Dalton-billiard ball model (1803)
2.
Thompson – plum-pudding model (1897)
3.
Rutherford – Nuclear model of the atom (1911)
4.
Bohr – uses quantized energy of the atom (1913)
5.
Quantum Mechanical Model of the Atom (1926)
ll. Problems with the Bohr Model
A. The model is fundamentally
incorrect and only works with
hydrogen.
B. Failed to explain the spectrum
of any other element
C. Did not account for the
chemical behavior of atoms
D. Electrons do not move around
the nucleus in circular orbits
E. Laid ground for later atomic
models.
lll. Quantum Mechanical Model
of the Atom
A. Quantum Mechanical Model is the current
description of electrons in atoms.
1. It does not describe the electron’s path around
the nucleus
B. Quantum Mechanical Model based on
several ideas including:
1. Schrodinger wave equation (1926) is
mathematical equation describing the behavior
of an electron and treats electrons as waves.
2. Heisenberg uncertainty principle (1927) states
that it is impossible to know both the velocity
and position of a particle at the same time.
lV. Atomic Orbital
A. Using the quantum mechanical model you
can predict the electron’s location in an
atom
B. An atomic orbital is a region of space in
which there is a high probability of finding
an electron
1. Orbitals are not necessarily spherical
How are these different from the
orbitals found in Bohr’s model?
Question Time
 What
is the Schrodinger Equation?
 How does it treat electrons?
 What is the Heisenberg Uncertainty
Principle?
 What is an atomic orbital?
V. Quantum Numbers
A. The Quantum Mechanical Model assigns
quantum numbers to indicate the
relative sizes and energies of atomic
orbitals.
B. There are three things for every electron
1. Principal energy level (principal quantum number,
n)
2. Energy Sublevel (s, p, d, f)
3. Atomic orbital
Vl. Principal Energy Levels
What tool do you think we use to find the energy levels of
the electrons?
A. Principal energy levels n =1
to 7. (Row # on the periodic
table)
B.
The electron’s principal
energy level is based on its
location around the nucleus.
C. Electrons closer to the nucleus
are at a lower energy level
and have lower energy than
those farther away from the
nucleus
How is this similar to Bohr’s model?
Different?
Question Time
 What
do quantum numbers indicate?
 What is the principal energy level
based on?
 Describe the energy as you go further
from the nucleus
Vll. Energy Sublevels and Orbitals
A. Energy sublevels
1. assigned letters s, p, d or f (smart people do fine)
i. Energy sublevels correspond to a shape where
the electron is likely to be found.
B. Orbitals – describes the electron’s location
1. 2 electrons per orbital
2. s sublevel has 1 orbital (2 electrons total)
3. p sublevel has 3 orbital (6 electrons total)
4. d sublevel has 5 orbital (10 electrons total )
5. f sublevel has 7 orbital (14 electrons total)
Looking at the periodic table can you see any
connections to the orbitals and sublevels ?
Energy Level
(n)
Sublevels
(Type of orbital)
Number of
orbitals per
sublevel
Number of
electrons per
sublevel
1
s
1
2
2
s
p
1
3
2
6
3
s
p
d
f
1
3
5
7
2
6
10
14
4
s
p
d
f
1
3
5
7
2
6
10
14
s orbital (1) - spherical
p orbitals (3) – dumb-bell
shaped
d orbitals (5)
f-orbitals (7)
Question Time
 What
letters are assigned to the
energy sublevels?
 How many orbital(s) does the s
sublevel have? p sublevel? d sublevel?
f sublevel?
 How many electrons can one orbital
hold?