AP Chem Test Chapter 6

Bohr model rule

1. Electrons in atom can only occupy certain orbits (corresponding to certain energies) 2. Electrons in permitted orbits have specific, "allowed" energies; these energies will not be radiated from the atom 3. Energy is only absorbed or emitted in such a way as to move an electron from one "allowed" energy state to another; the energy is defined by E= hv

Rydberg Equation

1/λ = R (1/m^2 - 1/n^2) M=final N= initial R= 1.097 * 10^-2 As energy levels INCREASE, energy ABSORBED As energy levels DECREASE, energy EMITTED

What is the maximum number of electrons in an atom that can have the following quantum numbers? Part A Part complete n =4, l=3

14 electrons

Identify the group of elements that corresponds to the following generalized electron configuration: [noble gas]ns2(n−1)d10np1[noble gas]ns2(n−1)d10np1

3A

The average distance from the nucleus of a 3s3s electron in a chlorine atom is smaller than that for a 3p3p electron. In light of this fact, which orbital is higher in energy?

3p higher in energy

Identify the group of elements that corresponds to the following generalized electron configuration: [noble gas]ns2(n−1)d2

4B

Angular momentum quantum number L

Allowed values of l are integers ranging from 0 to n-1 l= 0 S l= 1 P l= 2 D l=3 F

Energies of Orbitals (many-electron atoms)

As # electrons increases, so does repulsion between them In atoms w more than one electron, not all orbitals on same energy level degenerate Orbital sets in same sublevel still degenerate Energy levels start to overlap in energy (4s lower in energy than 3d)

If you put 120 volts of electricity through a pickle, the pickle will smoke and start glowing orange-yellow. The light is emitted because sodium ions in the pickle become excited; their return to the ground state results in light emission.

E = h*frequency, where h = 6.626e-34 Js, Planck's constant E = 6.626e-34 Js *(5.09e14 s^-1) = 3.37 e-19 J (per photon) 0.10 mol *(6.022e23 /mol) *(3.37e-19 J) = 20.3 kJ

Titanium metal requires a photon with a minimum energy of 6.94×10−19J to emit electrons. Part A What is the minimum frequency of light necessary to emit electrons from titanium via the photoelectric effect?

E= hv E/h= v(frequency) ν = 1.05×10^15 s−1s−1

Photoelectric effect equation

E=hv E= hc/λ h= Planck's constant= 6.626 * 10^-34

Electron configurations

Electrons generally occupy the lowest energy orbital first.In the Li atom, the 3s, 3p, and 3d orbitals have different energies.The CC atom has two unpaired electrons.

Kinetic energy of photon

Ep- W0

Energies of orbitals- Hydrogen

For a one electron hydrogen atom, orbitals on the same energy level have the same energy DEGENERATE ORBITALS

Hund's Rule

For degenerate orbitals, the lowest energy state is attained when the number of electrons with the same spin is maximized. So for a degenerate set of orbitals, one electron goes into each orbital until all the orbitals of the subshell are half-filled. Once all the orbitals of the subshell are half-filled the pairing of electrons can take place.

Identify the group of elements that corresponds to the following generalized electron configuration: [noble gas]ns2np5

Halogens

What is the kinetic energy of the emitted electrons when cesium is exposed to UV rays of frequency 1.50×1015Hz

KE= Ep- W0 W0= h(threshold frequency)

Also, since E=hνE=hν, the equation can also be written as

KE=E−ϕ

Kinetic energy equation photoelectric effect

KE=hν−hν0 V0= initial frequency

Relationship between

Light and mass MATTER EXHBITS WAVE PROPERTIES

How to order orbital

Lower energy subshells fill before higher energy subshells. The order of filling is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p. The periodic table can be used to help you remember this order. An orbital can hold up to two electrons, which must have opposite spins. Hund's rule states that if two or more orbitals with the same energy are available, one electron goes in each until all are half full. The electrons in the half-filled orbitals all have the same value of their spin quantum number.

Wo

Minimum energy required to remove electron

Is it possible to eject electrons from titanium metal using visible light?

NO, because 2.86*10^7 m falls in UV zone NOT visible light zone if outside zone then impossible to eject

Pauli's exclusion principle

No two electrons in an atom can have the same set of four quantum numbers (n, ℓll, mℓl, and ms). CANNOT HAVE SAME SPIN/TWO ELECTRONS FACING SAME DIRECTION

Aufbau Principle

The aufbau principle: Electrons are added to the lowest energy orbitals available

How would the dx2−y2dx2−y2 orbital in the n=5n=5 shell compare to the dx2−y2dx2−y2 orbital in the n=3n=3 subshell?

The contour of the orbital would extend further out along the x and y axes. The radial probability function would include two more nodes. The mℓmℓ value would be the same.

Equation for wavelength/frequency

c = λv, "drowning sheep" make sure to convert wavelength to m before solving

Threshold frequency

the minimum frequency of light required to produce the photoelectric effect

F orbitals

their shapes are even more complex than s, p, or d orbitals; can hold a total of 14 electrons in 7 sub-shells

Would you expect it to require more or less energy to remove a 3s electron from the chlorine atom, as compared with a 2p electron?

more energy for 2p electron

D orbitals

most have 4 lobes; and their destiny runs along the axes; can hold a total of 10 electrons in 5 sub-shells

S orbitals

-Spherical shape with electron densities highest near nucleus -Electron distribution exhibits maxima at finite distance from nucleus as n increases electron density more spread out and greater probability of finding electron far away from nucleus

Indicate the number of unpaired electrons for following: [noble gas]ns2np5

1

Which of the following represent impossible combinations of nn and ll?

1p2d

What is the maximum number of electrons in an atom that can have the following quantum numbers? Part A Part complete n = 3, ml = -2

2 electrons

What is the maximum number of electrons that can be freed by a a burst of light of 233 nmnm whose total energy is 2.00 μJ.

The energy of each photon can be obtained using Planck's equation: E = hν = (hc)/λ = (6.626 x 10-34 J s)(2.9979 x 108 m/s) / (233 x 10-9 m) = 8.525 x 10-19 J The maximum kinetic energy for each freed electron will be 8.525 x 10-19 J - 6.94 x 10-19 J = 1.585 x 10-19 J The number of 233 nm photons in the 2.00 x 10-6 J burst of light will be 2.00 x 10-6 J / 8.525 x 10-19 J = 2.346 x 1012 photons. Each photon can free at most one electron, so the maximum number of freed electrons will be 2.346 x 10^12 electrons.

Spin quantum number

The quantum number that has only two possible values, +1/2 and -1/2, which indicate the two fundamental spin states of an electron in an orbital TWO ELECTRONS CANNOT HAVE SAME SPIN VALUE

Energy of a photon equation

W0 + Ke

P orbitals

dumbbell shaped