ATOMS #2: QUANTUM MECHANICS
^What to catch from the slide:
This is the double-slit experiment where scientists discovered that light had both particle and wave properties --> this is because light travelling through the two slits on the left hand side made multiple marks on the gray screen on the right. This could only be explained by the wave-like behaviour of light.
WAVE-PARTICLE DUALITY
^What to catch from the above slide:
What is important is the formula. Know how to use this as it will show up on the exam
1st FORMULAT YOU NEED TO KNOW:
λ = wavelength (m)
h = Planck's constant (6.626 x 10^-34 J x s)
p = momentum (kg x m/s)
m = mass (kg)
u = speed (m/s)
^What to catch from the above slide:
This is a sample question that puts the previous formula to use.
They can very well ask about the speed of an electron, or about big objects such as cars and planes
Heisenberg's Uncertainty Principle
^What to catch from the above slide:
Once again, you need to know the formula and how it works
The formula in the blue box allows you to calculate both uncertainty in position as well as uncertainty in momentum: whichever one you are looking for, you want to isolate that specific variable!
2nd FORMULA YOU NEED TO KNOW:
h = Planck's constant
^What to catch from the above slide:
Note that the question will either ask about precision or uncertainty of POSITION or MOMENTUM; in which case, you simply isolate that variable (either x or p) and solve for it.
QUANTUM NUMBERS
^What to catch from the above slide:
Each electron has a specific set of quantum numbers. It is like a distinct barcode every different product has in Walmart.
n = principle shell, which gives you the energy level (obviously, the higher the n value, the more energy): You must realize for instance, 3p has HIGHER ENERGY than 2p, this is because 3p has n = 3, and 2p has n = 2.
l = sub shell, which gives you the shape of the orbital (namely s, p, d, f) --> note that l = 0 gives you "s" orbital, l = 1 gives you "p" orbital, l = 2 gives you "d" orbital, and l = 3 gives you "f" orbital (refer to above slide as well)
ml = orbital, which gives you the orientation of orbital
^What to catch from the above slide:
l = 0 would indicate that ml would also equal 0. This gives you total 1 orbital, in which 2 electrons could be filled. This is because each orbital can fill up to 2 electrons
l = 1 would indicate ml will be equal to -1, 0, +1, following the -l, 0, +l rule --> the number of ml values is equivalent to the number of orbitals you have. When l = 1, it has a total 3 ml values, which equates to 3 orbitals, which are able to accommodate 6 electrons in total.
l = 2 would mean ml is -2, -1, 0, +1, +2. This means there is a total of 5 orbitals, which can accommodate 10 electrons
l = 3 would mean ml is -3, -2, -1, 0, +1, +2, +3. This means there is a total of 7 orbitals, which can accommodate 14 electrons
PRACTICE QUESTIONS ON QUANTUM NUMBERS
ANSWER KEY
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