Molar Masses & Atoms
Quantum Chemistry
Electron Configurations
Subatomic particles, ions, isotopes
100
Calculate the formula mass for C2H5O3
77.06 u
100
What is the energy of a photon with a wavelength of 450 nm?
4.42 x 10-19 J
100
How many electrons are in a p-orbital?
2 electrons
100
Which statement about subatomic particles is correct?
a. Neutrons and electrons have the same charge but different masses.
b. Protons and neutrons are found in the nucleus, while electrons orbit the nucleus.
c. Protons and electrons have the same mass but opposite charges.
d. Neutrons carry a negative charge.
B.Protons and neutrons reside in the nucleus at the center of the atom, while electrons move around the nucleus in orbitals.
200
How many moles of NH3 are present in 78.2 gram sample?
4.59 moles NH3
200
What is the wavelength of a photon that has an energy of 8.25 x 10-19J
291 nm
200
What is the electron configuration of Sulfur?
[Ne]3s23p4
200
An ion is formed when an atom gains or loses neutrons.
- True
- False
False- An ion forms when an atom gains or loses electrons, not neutrons. Gaining or losing neutrons forms isotopes.
300
What is the mass in grams of 5.23x1023 nickel atoms?
(Avagadro's #: 6.02x1023)
51.0 grams Ni
300
What is the electron configuration for sodium? What are the inner electrons and outer electrons?
1s22s22p63s1
all inner electrons except 3s1
300
What is the electron configuration of an Cl- ion?
[Ne]3s23p6
300
An ion of chlorine has 17 protons, 18 neutrons, and 18 electrons.
a. What is the mass number of this ion?
b. What is the charge of the ion?
- Mass Number: 35
- Charge: -1 (This is a chloride ion, Cl⁻)
400
How many grams are there in 1.5x1025 molecules of CO2?
109.59 g CO2
400
A photon of light has an energy of 1.34x10-18 J. What is the wavelength of this light in nanometers? (h=6.63x10-34J/s) (c=3.00x108m/s)
149 nm
400
What element has the electron configuration of 1s22s22p63s23p2?
Silicon
400
An element has three isotopes:
- Isotope 1 with a mass of 35.0 amu and an abundance of 25.0%.
- Isotope 2 with a mass of 36.0 amu and an abundance of 50.0%.
- Isotope 3 with a mass of 37.0 amu and an abundance of 25.0%.
Calculate the average atomic mass of the element.
Average Atomic Mass=(35.0×0.25)+(36.0×0.50)+(37.0×0.25) = 8.75 + 18.00 + 9.25 = 36.00 amu
=8.75+18.00+9.25=36.00amu
Answer: 36.00 amu