Conceptual Learning Unit 1: Atomic Theory

Question 1

Line Spectra In hydrogen

Answer 1

-Only specific wavelengths are associated with transitions.
-There are discrete energy levels that the electron is moving between. The energy of the light of the transitions corresponds to the difference in energy between two of these levels
***IF THE ENERGY OF THE ELCTRON IS INCREASING, THIS IS FROM ABSORPTION OF THE LIGHT ENERGY. IF THE LIGHT IS BEING EMITTED, THIS IS FROM THE ENERGY OF THE ELECTRON DECREASING

Question 2

Red Light Spectrum

Answer 2

625-640

Question 3

Orange

Answer 3

590 - 625

Question 4

Yellow

Answer 4

565 - 590

Question 5

Green

Answer 5

520 - 565

Question 6

Cyan

Answer 6

500 - 520

Question 7

Blue

Answer 7

435 - 500

Question 8

Violet

Answer 8

380 - 435

Question 9

Rydberg Equation description

Answer 9

-Calculating the wavelength of light emitted by an electron moving between the energy levels of an atom.
-When an electron shift from a high-energy orbital to a lower-energy orbital, a photon of light is created. A photon of light is absorbed by the atom when an electron moves from a low-energy to a higher-energy state. The Rydberg Formula can be used to compute various elements’ spectra.

Question 10

Rydberg characteristics

Answer 10

-Energy starts from n=1 then counts up
-If the final state is larger than the initial state this is an ABSORBTION of energy (photon) (positive number)
-If the final state is less than the initial state this is an emission of energy (photon) (negative #)

Question 11

De Broglie’s Equation

Answer 11

-Since energy with measurable wave-like characteristics could be treated as a particle (photon) then actual particles with real mass should have a corresponding wave associated with them.
-Matter waves are dependent on the particles mass
-equation makes it easy to calculate the associated wavelength of any moving particle with the use of this formula

Question 12

Wavefunction

Answer 12

function (given by the symbol psi) that describes that the wavefunction helps understand where the electron is. The square of the wavefunction is related to the probability of finding the particle in a particular point in space

Question 13

Ground state

Answer 13

-We are the most interested in the lowest energy solution which is the ground state because it is the most stable state of the electron in an H-atom.
-known as the zero-point energy

Question 14

Degenerate Solutions

Answer 14

-Next highest energy solutions we discover that there are many solutions with the same energy.
-As we move up in energy we find another group of degenerate solutions with a different higher energy.

Question 15

The Schrödinger Equation

Answer 15

-Differential equation that we solve to get all the wavefunctions that will describe the electron energy levels within the atom.
-Kinetic and Potential energies are split into two parts and combine for the total energy.
-(Kinetic Energy + Potential Energy = Total Energy) to obtain information about the behavior of an electron bound to a nucleus.

Question 16

Principal Quantum number

Answer 16

distance from the nucleus

Question 17

Angular momentum Quantum number

Answer 17

Shape

Question 18

Magnetic quantum number

Answer 18

orientation in shape

Question 19

Principal Quantum Number, n

Answer 19

-The most important because this number is related to the energy associated with that particular wavefunction.
-All solutions with the same n values are degenerate (have the same energy)
-The more stable energies must all be negative. The more negative, the more stable

Question 20

Orbital notations

Answer 20

-Simply a different means that chemists use to describe the wavefunction for a hydrogen atom.
-The orbital notion uses only the n and l quantum numbers

Question 21

Radial Distribution functions

Answer 21

-When the wavefunction is squared the result is the electron density.
-It allows use to calculate the electron density and also the probability at the various distances from the nucleus (possible radii for the electrons)

Question 22

Radial Distribution important characteristics

Answer 22

-The greatest probability for the 3 curves progresses to distances further away from the nucleus (nucleus is at zero).
You conclude that a 3s orbital is slightly larger than a 2s orbital which is slightly larger than a 1s orbitals.

Question 23

Orbital Shapes

Answer 23

-The hydrogen atoms orbitals are the wavefunction portion of the quantum mechanical solution to the hydrogen atom.
-The orbitals offer us a picture of the electron in a hydrogen atom

Question 24

Key features of an orbital

Answer 24

-The distribution of the electron away from the nucleus; Known as the radial distribution
-The shape of the orbital and is the angular distribution.
-The radial distribution is mostly dependent on the principle quantum number b.
-The angular distribution depends on l an ml

Question 25

Photons

Answer 25

-We can think of the energy of light as being packaged up into small pieces with a particular energy.
-The energy of these photons is proportional to the frequency of the light, and the proportionality constant is called planks constant.

Question 26

Why do we think of the energy as being packaged like this?

Answer 26

-We find that the interaction of light and electrons consist of one photon for each electron.
-if we have a bigger and brighter light sources, they have more total energy.
-The energy per photon is only determined by the frequency and is the only value that matters for the electron

Question 27

Photoelectric effect

Answer 27

-The photoelectric effect is simply the effect that sometimes when you shine light on a metal, electrons are ejected
-Unless light of sufficient frequency is used, then no electrons are ejected. That is there is a threshold below which no matter how intense the light source is, no electrons leave the metal.
-If you are using light of a sufficient frequency, then as the light source is increased in intensity (brightness), the number of electrons ejected increases.
-As the frequency is increased above the threshold, the velocity of the ejected electrons increases.
-From this we can conclude that energy is proportional to frequency, and that the proportionality constant is Planck’s constant,
h

Question 28

Work function equation

Answer 28

-The maximum kinetic energy of the electron is the energy of the photon minus the threshold energy. This threshold energy we call the “work function” and we give it the symbol Φ
-We can predict the maximum velocity of the electron for a given frequency if we know the work function, or
-We can calculate the work function by measuring the maximum velocity for a given frequency
-The energy of the photon must equal the sum of the work function (the potential energy that needs to be overcome for the electron to “escape”) plus the kinetic energy of the electron

Question 29

Wave Particle Duality

Answer 29

-Often discussed in terms of electrons being both waves and particles
-Exists in other situations such as electron-magnetic radiation

Question 30

Heisenberg uncertainty principle

Answer 30

-States that there is a minimum product of the uncertainties of position and momentum
-two uncertainties must be not only finite but greater than h/4π.
-we can know quite a bit about the location and momentum – we just can’t know them exactly
-the only times these uncertainties are relevant is when we are interested in very small distances (like distances in atoms and molecules) and when we are interested in very small momentums (like those for particles with small masses like an electron).