The Atom

1
The Atom
2
Atomic models
Thompsons plum pudding! 1.negative charges (e)
like plums surrounded by positive charges (the
pudding) creating the volume of an atom! He was
wrong!
3
Atomic models
Rutherfords Planet model 1.Bounced particles off
metal foil. 2. Most passed through, some
deflected through large angle. 3. Predicted
planetary model w/ electrons orbiting positive
nucleus. Problems??? - acclerating nucleus
should produce EM waves ( electrons should
radiate energy fall into nuc.) - Atoms emit
only certain EM radiation, not all continous
frequencies!
Rutherford
4
Atomic models
Bohrs Quantum Atom 1.Electron moves only in
permitted orbits.(quantized States) 2. Electron
does not emit energy when it is in one of the
allowed orbits. stationary state 3. When
electrons jump from one state to the
other, Energy is given off as a particular
photon with energy to the difference in energies
of the initial and final States hf Ei - Ef
5
De Brogile Answers why
Why discrete energy levels 1.Orbit is only stable
with whole values of whole number electron dr
Brogile waves.
6
De Brogile Answers why
Why discrete energy levels 1.Orbit is only stable
with whole values of whole number electron dr
Brogile waves.
7
wavelength of matter waves
De Brogiles wavelength Plancks
constant momentum
8
frequency of matter waves
De Broglies frequency Energy
Plancks constant
9
6.63 x 10 - 34 J s / .05kg (40 m/s) 3.32 x 10
-34 m
10
What is the deBroglies wavelength of a .05kg
rock at a speed of 40 m/s?
11
E6 E5 E4 E3 E2

H
12
(No Transcript)
13
E6 E5 E4 E3 E2

Emitting photons lowers energy levels
- E
E
H
14
2
15
How much is the energy of a hydrogen electron in
the third state?
16
How much is the energy of a hydrogen electron in
the third state?
2
-1.5eV
17
For a hydrogen atom determine A) Energy of
innermost energy level (n1) B)Energy of 2nd and
3rd level C)Energy difference between levels 2
and 3
2
18
Energy of photon yields Energy released
2
2
n1 would be the ground state, hence, a 13.6 eV
would be needed to release an electron
19
2
2
What is the wavelength of the line in the visable
spectrum of atomic hydrogen specified by the
value n2 5)?
20
2
2
What is the wavelength of the line in the visable
spectrum of atomic hydrogen specified by the
value of n1 2 and n2 5)?
a) Solve for E using equation to get 2.86 eV
3 x 10 8 (4.15 x 10 -15) eV s 2.86 eV 4.35 x
10 -7
21

• A hydrogen electron in its third quantum state
  has an orbital radius of about 4.5 x 10 -10 m.
  Find its
• Wavelength
• Momentum
• Kinetic energy

22

• A hydrogen electron in its third quantum state
  has an orbital radius of about 4.5 x 10 -10 m.
  Find its
• Wavelength (1/3 circ)
• Momentum (h /?/)
• 7.0 x 10-24 kg m/s

23
Atomic models
Bohrs Quantum Atom 1.Electron moves only in
permitted orbits.(quantized States) 2. Electron
does not emit energy when it is in one of the
allowed orbits. stationary state 3. When
electrons jump from one state to the
other, Energy is given off as a particular
photon with energy to the difference in energies
of the initial and final States hf Ei - Ef
24
A hydrogen atomdrops from n2 to n1 energy
level. A) Energy of a photon emitted B)calculate
frequency of photon emitted C)wavelength of the
photon emmitted
Hint for B is there are 1.6 x 10 -19 J / eV