Exam 3 Topics Flashcards
Hess’s Law
The enthalpy change of an overall process is the sum of the enthalpy changes of its individual steps
Formula for delta H of rxn
Sum of products - sum of reactants
Frequency
Number of complete waves (v) in hertz
Speed of light (c)
3.00 x 10^8 m/s
Speed of light equation
C= frequency x wavelength
Plancks constant
H= 6.626 x 10^-34 JxS
Ground state value
-2.18x10^-18 J
Absorption
If an H atom absorbs a photon, the electron moves to a higher energy orbit
Emission
If a H atom in a higher energy level returns to a lower energy level, it emits a photon
Principle quantum number (n)
Indicates relative size of orbital and distance away from nucleus
Angular momentum quantum number (l)
Shape of orbital.
N=1, l=0
N=2, l=0,1
N=3, l=0,1,2
Magnetic quantum number (ml)
Three dimensional orientation of orbital
Ex l=1 so ml=-1,0,1
Sublevels (l values)
l=0 is s sublevel
l=1 is p sublevel
l=2 is d sublevel
l=3 is f sublevel
Spin quantum number (ms)
Two possible values +1/2 or -1/2
The exclusion principle
No two electrons in the same atom can have the same 4 quantum numbers
Diamagnetic
Paired e-
Paramagnetic
Unpaired e-
Ionization energy
Decreases down a group and increases across a period
Oxidation numbers
Number of valence electrons -(number of shared e- + number of unshared e-)
Formal charge
(Number of valence e-)- (number of unshared e- + 1/2 number of shared e-)
Free radicals
Species that contain a lone unpaired electron
3 steps for Hess Law
- Identify target equation (unknown 🔺H)
- Adjust the equations with the known 🔺H values so that the “target” amount of moles of each substance is correct
- Add adjusted equations and delta H values to get the target equation and its delta H. Cancel out what is the same and if reversing, switch the sign.
