General Chemistry Unit 3

A. Particles  1. alpha particle - helium nucleus with 2 protons, 2 neutrons  2. beta particle - electron or positron ejected from nucleus  B. Energy - gamma rays (like x-rays)

 A. EM (electromagnetic) energy  Equations:  E = hv  v = frequency (Hz) E = energy h = Planck's constant (6.626 x J/Hz)  λ = c/v  c = speed of light (3.00 x 10 8 m/s)  λ = wavelength (nm)  Relationships: E/v = constant (direct) λv = constant (inverse) E and λ are inversely related So high energies are associated with high frequencies and lower wavelengths

 What is the wavelength of light (in nm) whose frequency is x Hz?  λ = c/ν  So λ = 3.00 x 10 8 m/s = 4.00 x m x /s 

 B. Emission spectrum: wavelength given off by energized electrons in the element  Ground state: lowest energy state of an atom  Excited state: atom has higher potential energy than in ground state  C. Absorption spectrum: wavelength absorbed as light passes through the element vapor (same lines as in emission)

 A. wave-particle duality of nature - we only see the wave nature when particles are small and velocity is near c (speed of light)  B. Heisenberg uncertainty principle - the more you know about position the less you know about momentum  C. Found the probability of an electron's position at any time

 1. energy level (distance from nucleus)  2. sublevel (orbital shapes)  s is sphere shape  p is peanut shape  d is double peanut shape  f is flower shape

 3. orbital position in space (x,y,z axes)  each orbital can hold two electrons  s sublevel has 1 orbital  p sublevel has 3 orbitals  d sublevel has 5 orbitals  f sublevel has 7 orbitals  4. spin – clockwise or counterclockwise

 No two electrons in the same atom can have the same four quantum numbers  Must have opposite spins if they are in the same orbital

 Energy Level - Floor  Orbital shape (sublevel) – Type of Apartment: s -1 bedroom, p-3 bedroom, d-5, f-7  Orbital position - Which bedroom in apartment (1 person in each room before adding a roommate)  Spin - Which bed in bedroom? Bed by window is first taken (clockwise), bed by door (counterclockwise)

 1. Aufbau Principle: electrons will occupy lowest energy levels and shapes first (follow diagram)  2. Hund’s Rule: electrons will be alone in an orbital if possible - put one in each equal energy orbital before doubling up in any orbital in the same sublevel  Orbitals with the same energy requirement are called degenerate orbitals

 Atomic number 8, so has 8 electrons  Assign apartments for each electron (see board)

 1. Orbital Notation - shows all properties described by the four quantum numbers 1s  Orbitals shown by line, electron represented by arrow (up-clockwise, down-counterclockwise)  2. Electron Configuration - shows electrons down to the sublevels  Energy level and sublevel with superscript of how many electrons present 1s 2 2s 2 2p 6

 See board

 Shows outer energy level only (energy level with the highest number in front)  a. Dot arrangement: symbol goes in the center E  (draw in numbers to show dot order)  b. 8 dots maximum: next energy level begins to fill after the p sublevel - only highest level is shown even if lower level is not complete

 Begin the configuration with the symbol for the noble gas from the row above your element. Put it in brackets with the number of electrons above it (the atomic number of the gas).  Beginning with the s level of the period that contains your element, continue to fill orbitals until the total number of electrons (all superscripts added together) matches your element’s atomic number.

 Phosphorus – Atomic number 15  Find noble gas above P – put in brackets  [Ne] (has 10 electrons already – only need to show 5 more)  Start with s electrons on energy level of period that P is on  3 rd period – so begin with 3s electrons  Continue filling until electrons equal atomic number  [Ne] 3s 2 3p 3  Indium – Atomic number 49  [Kr] 5s 2 4d 10 5p 1

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