Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric...
-
Upload
darleen-short -
Category
Documents
-
view
222 -
download
1
Transcript of Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric...
![Page 1: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/1.jpg)
Light and Electrons
![Page 2: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/2.jpg)
Electromagnetic Radiation
Light is electromagnetic radiation: combined electric and magnetic wavesSourc
e Electric vector
Magnetic vector
direction of propagation
![Page 3: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/3.jpg)
Electromagnetic Radiation
Light is more than what we can see…
![Page 4: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/4.jpg)
Electromagnetic Radiation
Subatomic particles (electron, photon, proton, etc) exhibit both PARTICLE and WAVE properties. This is known as Wave-Particle Duality.
Diffraction: wave-like
Photoelectric Effect: particle-like
![Page 5: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/5.jpg)
Electromagnetic Radiation
Wave Properties of Light:
1. It’s fast! …c = 3.0 x 108 m/s
2. It relfects, refracts, diffracts (Transverse wave)
3.
![Page 6: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/6.jpg)
All light waves have frequencywavelength
symbol: f (Greek “lambda”)
units: “cycles per sec” = Hertz “distance” (m, nm)
where c = velocity of light = 3.00 x 108 m/sec
Electromagnetic Radiation
c = f
Increasing frequency
![Page 7: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/7.jpg)
Electromagnetic Radiation
Example: Red light has = 700 nm. Calculate the frequency, f.
=3.00 x 10
8 m/s
7.00 x 10-7
m
4.29 x 1014
Hz f = C
![Page 8: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/8.jpg)
Electromagnetic Radiation
Particle Properties of Light:
1. A particle of light is called a photon
2. Energy of a photon is calculated by E = h ·f
where E = energy (Joules, J)
f = frequency (Hertz, Hz, 1/sec)
h = Planck’s constant 6.63 x 10 J·s
-34
![Page 9: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/9.jpg)
Electromagnetic Radiation
Albert Einstein postulates the Photoelectric Effect to explain two observations:
1. No electrons are observed until a minimum energy is applied.
2. Number of electrons ejected depends upon light intensity – not light frequency!
![Page 10: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/10.jpg)
Light is created by the Photoelectric Effect
![Page 11: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/11.jpg)
Electromagnetic Radiation
The photoelectric effect and the idea of discrete, quantized energies neatly explain the observation of emission spectra.
![Page 12: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/12.jpg)
Electromagnetic Radiation
Example: Red light has = 700 nm. Calculate the energy per photon.
E = hf and c = f
So f = c/ and E = hc/
E = (6.63 x 10 Js)(3.0 x 10 m/s) 700 x 10 m
E = 2.84 x 10 J
-34 8
-19
-9
![Page 13: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/13.jpg)
Electron Orbitals
While thinking about the emission spectrum of hydrogen, Neils Bohr came up with the planetary model of the atom. In this model, electrons can only orbit the nucleus at discrete distances and particular orbital shape.
Orbital model of Na
Sharp-line spectrum of H
Neils Bohr
Electron Orbitals
![Page 14: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/14.jpg)
Electron Orbitals (n)
n = energy level or shell (n = 1, 2, 3, 4, 5, 6, 7)
1. Energy levels are whole numbers
2. The maximum number of electrons in each energy level equals 2n2.
3. The rows of the periodic table correspond to energy levels.1. Whole number energy levels – like a standing
wave
![Page 15: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/15.jpg)
3. The rows (periods) of the periodic table correspond to energy levels.
Electron Orbitals (n)
![Page 16: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/16.jpg)
Electron Orbitals (l)
l = subshell (s, p, d, f, g, h, i, j…)
1. s, p, d, and f are named after the four lines in the hydrogen emission spectrum…Sharp, Principle, Diffuse, Fundamental.
2. Each subshell has a different shape
3. The number of subshells in an energy level is equal to the number of the energy level.
Energy Level
Number of Sublevels
Name of sublevels
1 1 s
2 2 s, p
3 3 s, p ,d
4 4 s, p, d, f
![Page 17: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/17.jpg)
Electron Orbitals (l)
1. Sharp, Principle, Diffuse, and Fundamental refer to the way the spectral lines look. It was thought that electrons traveling between certain energy sublevels
produced those certain lines. This was not correct, but the names stuck.
![Page 18: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/18.jpg)
Electron Orbitals (l)
2. Each subshell has a different shape
s-orbital1.Has a
spherical shape
2.Can hold up to 2 electrons
3.Lowest energy subshell
![Page 19: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/19.jpg)
p-orbitals
Electron Orbitals (l)
1.Said to have a “dumbbell shape”
2.Can hold up to 6 electrons
![Page 20: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/20.jpg)
![Page 21: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/21.jpg)
Electron Orbitals (l)
d-orbitals
1.Said to have a “clover leaf” shape
2.Can hold up to 10 electrons
![Page 22: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/22.jpg)
combined orbitals
d-orbitals
![Page 23: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/23.jpg)
Electron Orbitals (l)
f-orbitals 1. Can hold up to 14 electrons
![Page 24: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/24.jpg)
combined orbitals
f-orbitals
![Page 25: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/25.jpg)
Electron Orbitals
To write a ground-state electron configuration:
1. Determine how many electrons are present.
2. Follow the Aufbau Diagram (Diagonal Rule)
Aufbau Diagram
![Page 26: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/26.jpg)
Electron Orbitals
Example: Write the ground-state electron configuration for nitrogen.
1. Nitrogen has 7 electrons
2. Follow the Aufbau Diagram
3. N: 1s22s22p3
![Page 27: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/27.jpg)
Electron Orbitals
So why does it work like this?
1. Pauli Exclusion Principle – states that “no two electrons in an atom can have the same set of four quantum numbers.” In other words, no atomic orbital can contain more than two electrons.
2. Hund’s Rule – The most stable arrangement of electrons around an atom is one with the maximum number of unpaired electrons. This minimizes electron-electron repulsion.
![Page 28: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/28.jpg)
Electron Orbitals
So why does it work like this? (cont.)
3. Aufbau Principle – Electrons occupy the lowest energy state possible.
4. Heisenberg Uncertainty Principle – The orbitals are probabilities – not shapes in space like planetary orbits. The uncertainty principle states that you cannot know the location and velocity of an electron simultaneously.
![Page 29: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/29.jpg)
s-orbitals in Zinc
![Page 30: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/30.jpg)
p-orbitals in Zinc
![Page 31: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/31.jpg)
Electron Configuration Shortcut…
![Page 32: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/32.jpg)
Electron Orbitals
Electron orbital notation goes one step further than electron configuration. It describes, specifically, each electron.
Compare them
Electron Configuration of Oxygen: 1s22s22p4
Electron Orbital Notation of Oxygen:
. . . . .
1s 2s 2p
![Page 33: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/33.jpg)
Electron Orbitals
Orbital Notation
s . or . or . 1s 2s 3s
p . . . 2p
d . . . . .3d
f . . . . . . .4f
![Page 34: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/34.jpg)
Electron Orbitals
Example: What is the electron orbital notation for sulfur?
. . . . . . . . .
1s 2s 2p 3s 3p
Example: What is the non-core electron orbital notation for gold?
[Xe] . . . . . .
6s 5d
![Page 35: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/35.jpg)
Electron OrbitalsElectron Orbitals
Example: What is the non-core electron orbital notation for gold?
[Xe] . . . . . .
6s 5d
…or more likely,
[Xe] . . . . . . 6s 5d
Electrons are more stable in full or half-full orbitals.
![Page 36: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/36.jpg)
Electron Orbitals
Octet Rule: Atoms will gain or lose electrons to achieve a full valence shell (usually this means 8 electrons).
Oxidation State: The value of the charge on an ion (positive or negative), after the atom has achieved a full valence shell.
- metals tend to lose electrons, forming positive (+) ions (cations).
- non-metals tend to gain electrons, forming negative (-) ions
(anions).
![Page 37: Light and Electrons. Electromagnetic Radiation Light is electromagnetic radiation: combined electric and magnetic waves Source Electric vector Magnetic.](https://reader035.fdocuments.net/reader035/viewer/2022062421/56649d035503460f949d63d9/html5/thumbnails/37.jpg)
Electron OrbitalsPeriodic Table of Oxidation States