Unit 1

Question 1

Wavelength and Frequency

Answer 1

Distance between 2 peaks or 2 troughs, units = m, it must be one full cycle of the wave.
Often talk about units and nanometers

Number of waves that pass through a given point per second, units=hz, seconds to the negative one.

Question 2

EM Scale

Answer 2

Increase in frequency - the scale for wavelength is going the opposite way because they are inversely proportional.
RADIOWAVES—- Long waves
RADARWAVES—- Speed traps
MICROWAVES—- Interacts with water and makes it rotate, excited rotational states… No water in a paper towel, it doesn’t heat
INFRARED— Night vision goggles, heat on pavement
VISIBLE SPECTRUM—- Happens to be wavelengths our eyes can see
UV—- Stronger wavelengths
X RAY— used for medicine
GAMMA RAY— Nuclear

Question 3

Amplitude - Constructive and Destructive Interference

Answer 3

Height of the wave, from CenterPoint of the wave to the top of the wave. We need It to see how waves interact, can be constructive or destruct. When they are lined up, they will create what’s like a double wave. In destructive waves they are not lined up and create destruction.

Question 4

Double Slit Experiment

Answer 4

DOUBLE SLIT EXPERIMENT - Experiment used to confirm that something is behaving as a wave, detector on the other side of the wall, on the screen it shows what we see on the screen. We point waves towards the wall with our slits, peaks are going towards the wall. The waves pan out around the wall. We can get constructive and destructive interference. You see a bright spot on the detector if its constructive. The brightest spot is midway between the slit, regions of constructive and destructive interference.
THIS IS CALLES A DIFFRACTION PATTERN.

Question 5

Photoelectric Effect

Answer 5

Light container, nothing inside ( no gasses) there is a metal surface and detective plate. The power source puts some charge on the plate. There is some negative charge and some positive charge. There is a current (flowing electrons). Scientist shine light on the plate, would sometimes be attracted to the plate, they would go around the circuit. Are they electrons being ejected or not. It takes energy to be taken away from the plate (binding energy), if there’s enough energy it can fly away with kinetic energy. Some energy goes to getting it off, the rest goes to giving it kinetic energy. ENERGY IS CONSERVED

SCIENTIST EXPECTED;
There was a minimum light intensity - they though intensity was related to the energy of the light. You actually needed the frequency not the intensity.
Above the min frequency, the KE increases with the light frequency - not true, as you increase the frequency of the light, the kinetic energy increased.
Above min frequency, light intensity increases the number of ejected electrons, but not their KE

Question 6

Photons

Answer 6

Discrete packets of energy

Question 7

Light in Packets of Energy

Answer 7

IF the energy is enough, the packet can leave. Whatever is not the binding energy, will be used for the kinetic energy, increase in frequency, increase in photon, increase in KE.
Increasing intensity - related to increasing the photons. Each photon can interact with one electron, more photons, more electrons ejected. Increasing the intensity is the increase in the number of photons.
Intensity can be thought about classically and quantically. It depends on the type of problem and what we are looking at.

Question 8

Electrons diffract

Answer 8

Electrons fired at coin (stack of atoms) and looked at a detector on the other side, expected to see dots corresponding. What was seen was a diffraction pattern.
Changed the conversation of how we think about electrons
Electrons diffract so we have wave character…

Question 9

Wave Particle Duality

Answer 9

Light -Both wave and particle character
Matter - Both particle and wave character

Question 10

Schrodinger’s Equation and Psi

Answer 10

The Schrodinger equation depends on electrons acting as waves…
Psi is a wave function or an orbital
Fork = psi, do math on the electron wave, you get back the same wave equation and energy. The wave equation can be solved exactly for only hydrogen. These psi’s are describing orbitals – electrons in orbitals as waves.

Question 11

Principal Quantum Number

Answer 11

Size and energy of the orbital

Question 12

Angular Momentum Quantum Number

Answer 12

Shape of the orbital

Question 13

Magnetic Quantum Number

Answer 13

Orientation of the orbital

Question 14

Electron Spin quantum number

Answer 14

+half or -half
must have opposing spins

Question 15

QUANTUM NUMBER RULES

Answer 15

Quantized = fixed, certain, discreet quantum numbers.

Principal = it can have positive whole numbers
Angular= allowed values depend on principal ( 0 to n-1)
Orientation = positive l to negative l

Question 16

Psi and E for every orbital

Answer 16

Psi - describes relative probability of finding electrons around nucleus
E - tells us how stable it is having that probability

Question 17

Distinct energy levels and differences between levels

Answer 17

When an electron moves like this, it is electron transitioning, we can calculate the energy of the orbital. We can then calculate the difference in energy. Extra energy is released as a photon (conserving energy). The photon has the same energy of the difference between the orbitals that is emitting the photon. We can then calculate the wavelength of the photon.
Emission = going down.
Need to give the electron the exact energy difference between the two levels, there are only certain allowed energy levels. The photon would not be absorbed if it is in between steps.
Has to be an energy match.

Question 18

Pauli Exclusion Principle

Answer 18

no two electrons in an atom can have the same values of all 4 quantum numbers.

Question 19

Effective nuclear charge

Answer 19

nuclear charge actually felt by an electron..

Question 20

Electron Nucleus Attractions

Answer 20

Stabilizing

Question 21

Electron Electron Repulsions

Answer 21

Destabilizing

Question 22

Aufbau Principle

Answer 22

Electrons will fill orbitals of lowest energy level

Question 23

Hund’s Rule

Answer 23

If two or more degenerate orbitals are available, one electron goes into each until they are all half-full. All electrons in half-filled orbitals have the same spin quantum number.

Question 24

Element properties - across the periodic table

Answer 24

adding more electrons to the same shell, the n value is the same distance from the nucleus - electrons aren’t affecting the size. Protons are also being adding - more charge in the nucleus, therefore a bigger pull from the nucleus and the electrons are pulled in more, making it smaller.

Question 25

Element properties as you go down the periodic table

Answer 25

Atoms get bigger as you go down the periodic table - more shells - larger atomic orbitals ( bigger n values), or the electrons are further from the nucleus.