Chapter 1 - Atomic Structure

Question 1

According to the Bohr model of the H atom,
the ionization energy is defined as

Answer 1

the energy required to move the electron from
𝑛 = 1 to 𝑛=∞

works for one electron systems

Question 2

Rubidium has a work function (φ) of 3.35 ×
10-19 J. What is the longest wavelength of light
which will cause electrons to be emitted?

Answer 2

The kinetic energy is 0 because longest wavelength gives just enough energy to overcome the work function, but no extra energy to provide the electron with kinetic energy

𝐾𝐸 = ℎ𝜈 − φ
ℎ𝜈 − φ = 0
𝜈 = φ/ℎ

solve for velocity
now solve for wavelength using l = c/v

Question 3

The ionization energy is the energy needed
to remove an electron from an atom. In the
Bohr model of the hydrogen atom, this means
exciting the electron to the n = ∞ state. What is
the ionization energy in kJ/mol, for hydrogen
atoms initially in the n = 5 energy level

Answer 3

Use the ionization energy formual

𝑬𝒏 = −𝟐. 𝟏𝟕𝟖 × 𝟏𝟎−𝟏𝟖𝑱 (𝒁𝟐
𝒏𝟐)

This is PER ATOM and now to find PER MOLE you gotta divide by 1000 and multiply by avogadro’s number

Question 4

Energy level series in atomic spectra for n=1, n=2, n=3

Answer 4

n = 1 UV
n = 2 visible
n = 3 infrared

UVI

Question 5

What is Aufbau’s principle?

Answer 5

Electrons fill in order of lowest sum of n + l or lowest n if same n + l

Question 6

Slater’s Rule

Answer 6

S and p electrons

0.35, 0.85, 1, 1,

D and f electrons
0.35, 1, 1, 1

Question 7

What is the effective nuclear charge of a one electron atom?

Answer 7

The same as the atomic number because no electron shielding occurs (electron shielding requires interaction)

Question 8

How is an atomic orbital node mathematically defined, and what does it physically represent

Answer 8

It is defined where 𝛹 = 0 AND 𝛹^2 = 0 due to radial or angular term.

It physically represents region of space where probably of finding an electron is 0

Question 9

What to look for to determine valid lewis structure

Answer 9

• Total electron count
• Violating octet rule

Question 10

When does the Rydberg equation work?

Answer 10

ONLY for hydrogen atoms, any other atom doesn’t have Zeff of 1 so it won’t work. Use sparingly

Question 11

Ionization energy of Ar is 1527 kj/mol. Lowest possible frequency of light to ionize the atom?

WATCH UR UNITS POR FAVOR

Answer 11

You have to convert IE to simply J/mol by dividing by avogadro’s number.

Make sure you’re in correct units!!!!

Question 12

Explain why each e- removal increases Zeff

Answer 12

Each e- removal increases Zeff and IE becuase number of shielding electrons decreases, so remaining electrons feel stronger pull by nucleus

Question 13

Provide the four explanations for trends in ionization energy

Answer 13

1) Effective nuclear charge (only works for atoms in the same row)
- Greater Zeff means greater IE becuase nucleus pulls stronger on e- so more energy required to remove an e-
- Greater Zeff means less shielding

2) Energy levels (shells)
- Electrons in higher n experience greater shielding and are less tightly bound to the nucleus so they have less IE

Both 1/2 have to do with the relationship IE is proportional to Zeff^2/n^2

3) Orbitals (also only works for atoms in the same level)
- S orbital has less energy and closer to nucleus compared to p orbital
- Higher orbital energy means smaller IE
S has higher IE than P

4) Spin pairing energy
Due to electron configuration, electron repulsion