Atomic Structure/Periodic Trends Review
Light
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Which of the following types of electromagnetic radiation has the highest energy – visible,
ultraviolet, microwave, infrared, X ray?
Which equation best expresses the energy of a photon? E = hv
What is the equation for frequency? V = c/wavelength
What is the wavelength of light that has a frequency of 4.00 X 1014 s-1? 750 nm
The bond energy of a carbon-carbon bond is approximately 350 kJ/mol.
a. Calculate the energy per C-C bond. (divide by 6.02 X 1023 = 5.81 X 10-19J)
b. Calculate the wavelength of the C-C bond. (E=hv = 342 nm)
Calculate the energy, frequency, and wavelength of the hydrogen atom as it goes from n=5 to
n=2. Does it absorb or emit energy? Emits because it will be a negative number
Atoms
1. What experiment was used to determine the charge of electron? Milikan’s oil drop
2. What is the definition of an isotope? Same number of protons, different number of neutrons
3. How many protons and electrons are in O-2? 8 protons, 10 electrons
4. What are the major findings from Rutherford’s gold foil experiment? There is a nucleus, it is
small and positively charged
5. Chlorine has two isotopes – Cl -35 which naturally occurs 75.78% and Cl-37 which naturally
occurs 24.22% of the time. Calculate the average atomic mass of chlorine. 35.45 amu
6. How many atoms of fluorine are present in 1 nanogram of fluorine?
7. How many moles of electrons are found in 800 g of Ca+2? 800g/40g = 20 mol * 18 e- = 360
8. When subjected to the flame test, what is the color of the flame when subjected to Cu+2 ions
and Sr+2 ions? Green and red, respectively
Electron Configurations
1. Which of the following atoms has the most unpaired electrons – Mg, Ti, Al, Cu, or Cr? Cr
2. Write an electron configuration of a noble gas. Any noble gas would have a full s and p orbital.
3. Write the electron configuration of Cu+2. [Ar] 3d9 (Remember: Copper will lose the 2 electrons
from the s orbital first).
4. Give the definition of a valence electron and core electron. Valence electrons are in the
outermost orbitals or s and p electrons in the highest energy level. Core electrons are all the
other electrons that are tightly held to the nucleus.
5. Write a ground state and a possible excited state electron configuration for Boron.
Ground state: Is22s22p1
Excited state: 1s22s23p1
6. How many unpaired electrons does phosphorus have? Is it paramagnetic or diamagnetic? 3
unpaired electrons, paramagnetic
7. If a hydrogen electron goes from n= 3 to n=1, what is happening? It is giving off light, going from
excited state to a ground state, losing energy, and emitting energy.
8. What rule states that no two electrons can have the same set of four quantum numbers? Pauli’s
exclusion rule
Quantum Numbers
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Which quantum number describes the shape of the orbital? L
What are the four quantum numbers that describe potassium? 4, 0, 0, +1/2
An electron with the four quantum numbers 3, 2, -1, -1/2 may be what element? Fe, Cr, etc.
What is the maximum number of electrons in the f orbital? 14
What is the difference between ml and ms? Ml is the number of orbitals and ms is the spin
Write the electron configuration with the orbitals and electron spins for lead. Write the
quantum numbers.
Periodic Trends
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What are most elements of the periodic table? Metals
What family does a solid element with two valence electrons belong to? Alkaline earth
What element is expected to have the largest third ionization energy – B, Be, C, N, Al? Be
Arrange the following elements and ions in increasing atomic radius – Be+2, Al+3, S-2, N-3.
Why does atomic radius decrease as you go across the periodic table? Shielding decreases or
nuclear charge increases and valence electrons are drawn in closer together/to the nucleus so
the atom is smaller in size
6. What is the trend and reasons for ionization energy? IE increases as you go across the periodic
table because of increasing atomic number . . . and without additional shielding and pulls
electrons in tighter (nuclear charge). It decreases as you go down the periodic table because
electrons are farther from the nucleus.
7. What is electron affinity? Energy associated with the addition of an electron (to a gaseous
atom).
8. What is the trend and reasons for electron affinity?