1. Where is the Electron Located?

2. WHAT IS ENERGY? ABILITY TO DO WORK MEASURED IN JOULES (J)
WORK: TO USE A FORCE TO MOVE AN OBJECT A DISTANCE
F X d
KINETIC: ENERGY DUE TO MOTION
POTENTIAL: ENERGY DUE TO POSITION

3. WHAT ARE THE DIFFERENT FORMS OF ENERGY?
Law Of Conservation of Energy (also known as the First Law of Thermodynamics): Energy cannot be created or destroyed it merely changes form
HEAT (THERMAL)
ELECTROMAGNETIC
CHEMICAL
NUCLEAR
MECHANICAL
SOUND
LIGHT (RADIANT)

4. THE DUALITY OF LIGHT
LIGHT IS A VIBRATION (WAVE) IN ELECTRIC AND MAGNETIC FIELDS THAT CAN TRAVEL ACROSS SPACE AS A PHOTON (PACKET OF ENERGY).
IT IS PART OF THE ELECTROMAGNETIC SPECTRUM.
LIGHT CAN BE REFLECTED, REFRACTED AND DIFFRACTED

5. WAVE PROPERTIES
WAVELENGTH (λ): DISTANCE BETWEEN TWO IDENTICAL POINTS ON A WAVE (METERS, m)
FREQUENCY (ƒ): NUMBER OF WAVES THAT PASS A FIXED POINT IN A SECOND (HERTZ, Hz)
SPEED OF LIGHT: c = ƒλ (3.00 X 108 m/s)

6. Waves

7. Albert Einstein
Suggested that electromagnetic radiation can be viewed as a stream of particles called photons
PHOTOELECTRIC EFFECT: Ejection of electrons from the surface of a metal or other material when high energy/frequency light shines on
E = h ƒ
E = Energy
H = Planck’s Constant(6.63 X 1034 J/s)
f = Frequency

8. Albert Einstein Developed the equation E = mc2 Energy has mass
We can calculate the mass of a photon

9. Arthur Compton Collided X-rays with electrons
Showed that photons do exhibit the mass from Einstein’s equation

10. Nature of Matter Max Planck – German physicist
Experimented with energy
Energy can be lost or gained only in whole-number multiples
Energy is “quantized”

11. Summary Energy is quantized
Electromagnetic radiation exhibits wave-like and particle-like behavior
Large pieces of matter mostly exhibit particle-like properties
Tiny pieces, like photons, exhibit mostly wave-like
Intermediate, like electrons, exhibit both

12. The Bohr Model Developed a quantum model for hydrogen
Electrons moved in circular orbits around the nucleus
Equation that can be used to calculate the change in energy when an electron changes orbits:
E = X 10-18J (Z2/n2)
n = an integer
Z = nuclear charge

13. BOHR’S ATOMIC THEORY

14. HOW CAN A LINE SPECTRA IDENTIFYAN ELEMENT?
LINE SPECTRUM: Shows only specific wavelengths of light (EM spectra)
What are uses of line
Spectra in technology?

15. The Bohr Model
Ground state – lowest possible energy state for an electron
Suppose an electron in level n = 6 of an excited hydrogen atom falls back to level n = 1. Calculate the change in energy when this happens.
ΔΕ = energy of final state – energy of initial state
What is the wavelength of the emitted photon?
E = X 10-18J (Z2/n2)
E = h ƒ
c = ƒλ (c = 3.00 X 108 m/s)

16. The Quantum Mechanical Model
Bohr’s equation only worked for hydrogen
Heisenberg, de Broglie, and Schrodinger developed the theory behind our current model
Schrodinger came up with a mathematical equation to describe the location of the electron
A specific wave function = an orbital
Led to the Heisenberg uncertainty principle and the exact speed of light (c)

17. The Quantum Model of the Atom
Heisenberg uncertainty principle: It is impossible to determine both the position and velocity of an electron or any other particle

18. What is the Address of the Electron?
Principle Quantum Number (n): Indicates the energy level occupied by an electron.
Angular Momentum (l): Indicates the shape of the orbital (s,p,d,f,g)

19. Atomic Numbers and Quantum Numbers
Magnetic Quantum Number (m): Indicates the orientation of an orbital around the nucleus.
Spin Quantum Number (↓↑): Indicates which way the electron is spinning

20. Quantum Numbers Symbol What It Means Acceptable Values n
Main energy level
1, 2, 3, 4, etc. l
Orbital shape
0, 1, 2,…n-1 ml
Space orientation
-l…0…+l ms
Electron spin
+1/2 and -1/2

21. What are the Rules Governing Electron Configuration?
Aufbau Principle: An electron occupies the lowest energy orbital available
Pauli Exclusion Principle: Only two electrons per orbital and they must spin in opposite directions
Hund’s Rule: Each orbital of equal energy must have one electron before a second electron is added

22. Let’s Fill Up The Orbitals!

23. Summary of Orbitals Principle Quantum # Sublevels Number of Orbitals
Number of Electrons 1 s 2
s, p 3 8
s, p, d 5 18 4
s, p, d, f 7 32

24. Exceptions to Aufbau