Chemistry
Chemistry Review (mid-term)
1. Use the equation for atomic mass to answer the following questions. (http://johnheilchem10.escuelacampoalegre.wikispaces.net/file/view/average+atomic+mass+calculations+-+3.pdf)
1. Argon has three naturally occurring isotopes: argon-36, argon-38, and argon-40. Based on argon’sreported atomic mass, which isotope do you think is the most abundant in nature? Explain.
2. Copper is made of two isotopes. Copper-63 is 69.17% abundant and it has a mass of 62.9296 amu.
Copper-65 is 30.83% abundant and it has a mass of 64.9278 amu. What is the weighted average mass of these two isotopes?
3. Calculate the atomic mass of silicon. The three silicon isotopes have atomic masses and relative abundances of 27.9769 amu (92.2297%), 28.9765 amu (4.6832%) and 29.9738 amu (3.0872%).
4. Gallium has two naturally occurring isotopes. The mass of gallium-69 is 68.9256 amu and it is 60.108% abundant. The mass of gallium-71 is 70.9247 amu and it is 39.892% abundant. Find the atomic mass of gallium.
5. Antimony has two naturally occurring isotopes. The mass of antimony-121 is 120.904 amu and the mass of antimony-123 is 122.904 amu. Using the average mass from the periodic table, find the abundance of each isotope. (Remember that the sum of the two abundances must be 100).
2. Draw the Lewis and VSEPR structures for the following 12 compounds and label them with their geometry. (http://butane.chem.uiuc.edu/cyerkes/Chem102AEFa07/worksheets/Worksheet%2015.pdf)
Lewis VSEPR Lewis VSEPR
a) SF6 b) ICl2
c) ICl4 d) SF4
e) CF4 f) BrF5
g) BrF3
1. Use the equation for atomic mass to answer the following questions. (http://johnheilchem10.escuelacampoalegre.wikispaces.net/file/view/average+atomic+mass+calculations+-+3.pdf)
1. Argon has three naturally occurring isotopes: argon-36, argon-38, and argon-40. Based on argon’sreported atomic mass, which isotope do you think is the most abundant in nature? Explain.
2. Copper is made of two isotopes. Copper-63 is 69.17% abundant and it has a mass of 62.9296 amu.
Copper-65 is 30.83% abundant and it has a mass of 64.9278 amu. What is the weighted average mass of these two isotopes?
3. Calculate the atomic mass of silicon. The three silicon isotopes have atomic masses and relative abundances of 27.9769 amu (92.2297%), 28.9765 amu (4.6832%) and 29.9738 amu (3.0872%).
4. Gallium has two naturally occurring isotopes. The mass of gallium-69 is 68.9256 amu and it is 60.108% abundant. The mass of gallium-71 is 70.9247 amu and it is 39.892% abundant. Find the atomic mass of gallium.
5. Antimony has two naturally occurring isotopes. The mass of antimony-121 is 120.904 amu and the mass of antimony-123 is 122.904 amu. Using the average mass from the periodic table, find the abundance of each isotope. (Remember that the sum of the two abundances must be 100).
2. Draw the Lewis and VSEPR structures for the following 12 compounds and label them with their geometry. (http://butane.chem.uiuc.edu/cyerkes/Chem102AEFa07/worksheets/Worksheet%2015.pdf)
Lewis VSEPR Lewis VSEPR
a) SF6 b) ICl2
c) ICl4 d) SF4
e) CF4 f) BrF5
g) BrF3