The Nature of Light Honors l Dual Nature

The Nature of Light (Honors) l Dual Nature of Light: l behaves as both waves and as particles (depending on what type of experiment is being performed. ) l Speed of Light: light waves travel at same velocity l C = 3. 0 x 108 meters/sec l l What is Light? https: //www. youtube. com/watch? v=e. CVPhj. Hh 57 E Greatest Discovery in Physics: (Duality of Light) https: // www. youtube. com/watch? v=XB-i. LRsq 8 A 8 https: //www. youtube. com/watch? v=XB-i. LRsq 8 A 8

Electromagnetic Spectrum l Spectral lines can come from all areas of EM Spectrum. l Visible colors make up only a small part

l EM waves carry different amounts of energy based upon their wavelength and frequency. Wavelength (λ): distance between two peaks of a wave Frequency (γ): number of peaks that pass per second. (Hertz (Hz) or cycles/sec) Which wave has higher energy? Relationship of Frequency, Wavelength and Energy of colored line http: //employees. oneonta. edu/viningwj/sims/plancks_equation_s. html

Calculating Energy of a Spectral Line (HONORS) STEP 1: Given wavelength of spectral line find it’s frequency. c=λxү c = the speed of light = 3 x 108 meters/sec λ = wavelength (in meters) 1 x 10 -9 meter = 1 nm 1 x 10 -10 meter = 1 Angstrom ү = frequency of the wave (Hertz or waves/sec, s-1)

Calculating Energy of a Spectral Line (HONORS) STEP 2: Using frequency find energy of the line (in Joules) E=hxү E = energy (Joules) h = Planck's constant = 6. 63 × 10 -34 kg x m 2 / sec ү = frequency of the wave (Hertz or waves/sec, s-1)

How are Electrons Organized? Energy Levels Sublevels Orbitals Spin The Electron Hotel

Energy Levels (1 -7) l Electrons exist at different distances from the nucleus. l Energy 1 Levels 2 3 Lowest energy Closest to nucleus 4 5 6 7 Highest energy Farthest from Nucleus

Sublevels (s, p, d, f) l Energy levels have certain number of sublevels. Energy Level Sublevels Possible 1 s 2 s, p 3 s, p, d 4 s, p, d, f 5 s, p, d, f, (g) 6 s, p, d, f, (g, h) 7 s, p, d, f, (g, h, i) Theoretical sublevels

Energy of Sublevels l Sublevels have different levels of energy. s Lowest energy p d f Highest energy

Orbitals in Sublevels l l Sublevels contain different numbers of orbitals. Maximum 2 electrons can exist in an orbital. Sublevel s p d f # of Orbitals 1 3 5 7 Max e- in Sublevel 2 e 6 e 10 e 14 e-

Aufbau Diagram l Shows: l order of electron filling l order of electron energy l Follow the “diagonal rule”

Writing Electron Configurations l Let’s write some electron configurations! l Ex: Magnesium l Follow the diagonal rule

l Some sublevels “overlap” l Results in certain sublevels having higher energy than others l Ex: 3 d has higher energy than 4 s Electron Configurations for Atoms http: //employees. oneonta. edu/viningwj/sims/atomic_electron_configurations_s 1. html Extremely Corny Song About Electron Configurations http: //www. youtube. com/watch? v=Vb 6 k. Axw. SWg. U&safe=active

Electron Spin l Electrons in an orbital spin in opposite directions l Pauli Exclusion Principle: In order for two electrons to occupy the same orbital, they must have opposite spins. Otherwise they create a magnetic field!

Orbital Diagrams l Show electrons in individual orbitals l s = 1 orbital, p = 3 orbitals, d = 5 orbitals, f = 7 orbitals l “Hund’s Rule for Orbital Filling” l When filling orbitals in a sublevel, place one electron in each orbital before adding the second.

Shapes of Orbitals l Orbitals come in different shapes and sizes. l Region of highest probability of finding an electron. l l Orbitals Shape & Energy & Spectral Line http: //www. youtube. com/watch? v=f. KYso 97 e. Js 4

s Orbital Probability cloud has a spherical shape

p Orbitals (px, py, pz) “Dumbell” shape Three p orbitals can exist, on the x, y, z axis in space

d Orbitals l Five possible d orbitals exist

f Orbitals l Seven possible f orbitals exist

Valence Electrons l Usually found in the s and p sublevels of highest occupied energy level. l How many valence electrons? l Draw a Lewis Dot Diagram of this element. l 1 s 22 p 63 s 23 p 64 s 23 d 104 p 2

Kernel l All electrons except the valence 1 s 22 p 63 s 23 p 3 l How many kernel electrons? l How many valence?

Excited vs. Ground State l Ground State: l Electron configuration you would normally write by following the order of filling l Lowest to highest energy. l Excited State: l one or more electrons have jumped up to a higher energy level. Ex: 1 s 22 p 63 s 23 p 54 s 23 d 104 p 3

Atom vs. Ion Configurations l Ions: atoms that have gained or lost electrons. l Figure out how many electrons the ion has then write configuration. l Ex: 20 Ca+2 has 18 electrons l 1 s 22 p 63 s 23 p 6 = 18 electrons Electron Configurations for Ions http: //employees. oneonta. edu/viningwj/sims/atomic_electron_configurations_s 2. html DONE!

Isoelectronic Species l Atoms and ions that have the same number of electrons. l Ex: Ar, K+1, Ca+2, P-3, O-2, Cl-1 l All have 18 electrons!

Impossible Configurations l Break the rules. Ex: 1 s 22 p 63 s 22 d 103 p 64 s 23 d 104 p 2 Ex: 1 s 22 s 32 p 63 s 23 p 6

s, p, d, f, “Blocks” l Indicates what sublevel is being filled last in the atom

Some Exceptions to Orbital Filling (HONORS) l When d and f sublevels get filled near the end of a configuration we sometimes see exceptions. l It is more stable for the orbitals of the d and f sublevels to be half filled or filled completely than to be one shy. l Electrons from the sublevel below get “promoted” up to make the atom more stable l Ex: Copper

Crash Course Chemistry: The Electron (13 minutes) l http: //www. youtube. com/watch? v=rc. Kil. E 9 Cda. A l l Quantum Mechanics and the Bohr Model (6 minutes) http: //www. youtube. com/watch? v=-YYBCNQn. YNM **Developing Modern Atomic Theory (6 min) Rutherford to Bohr to the Modern Model http: //youtu. be/45 KGS 1 Ro-sc The Uncertainty Principle (6 min) Honors Probability & Chance of Finding an e- and Orbital Shapes http: //www. youtube. com/watch? v=Fw 6 d. I 7 cgu. Cg