Chem 104 Unit 3 Group Work
(September 12th)
Name_______________________________
1. For each of the following isotopes, determine the number of protons, number of neutrons, mass number, atomic
number, electron configuration and. Please show the shorthand configuration for the last two.
Protons
(p)
Mass #
(p +n, A)
Neutrons
(n)
Atomic #
(p, Z )
Electron
configuration
orbital diagram
Carbon-13
Iron-55
119Sn
190Os
2. For each of the elements in Problem 1, determine the valence orbitals and number of valence electrons.
Valence orbitals
Valence electrons
Carbon-13
Iron-55
119
Sn
190
Os
3. How many unpaired electrons are in each of the following elements?
Element symbol / Element # / # unpaired electrons
Li /
Al /
P/
Cl /
Ti /
Cr /
Fe /
Ni /
Zn /
Element symbol / Element # / # unpaired electrons
Be /
Si /
S/
Sc /
V/
Mn /
Co /
Cu /
4. Magnesium has three naturally occurring isotopes. The most abundant, 24Mg, has an exact mass of 23.9850
amu and makes 78.99% of a sample of magnesium. Determine the natural abundance of the 25Mg (24.9858
amu) and 26Mg (25.9826 amu) isotopes.
Chem104 Unit 3 Group Work
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