Calculating Atomic Mass

What is the atomic mass of Lithium if 7.42% exists as lithium-6 and 92.58% exists as lithium- 7?

amu= 6.926

Magnesium has three naturally occurring isotopes. 78.70% of Magnesium atoms exist as Magnesium-24, 10.03% exist as Magnesium-25 and 11.17% exist as Magnesium-26. What is the atomic mass of Magnesium?

amu= 24.2997

Neon has two major isotopes, Neon-20 and Neon-22. Out of every 250 neon atoms, 225 will be Neon-20, and 25 will be Neon-22. What is the atomic mass of Neon?

amu= 20.2

Natural samples of copper contain two isotopes. Copper- 63 has a mass of

62.930 amu and Copper- 65 has a mass of 64.928 amu. The percent abundance of

Copper-63 is 69.09%. Calculate the atomic mass of copper.

63.55 amu

Calculate the atomic mass of an element if 60.4% of the atoms have a mass of 68.9257 amu and the rest have a mass of 70.9249 amu. Identify the element in the periodic table.

69.7 amu, Gallium

Copper metal is well-known since the dawn of civilization that has two isotopes, Cu-63 and Cu-65 that have atomic masses of 62.93 amu and 64.828 amu respectively. Their percent abundances are respectively 69.09 % and 30.91 %. Determine the average atomic mass of copper.

63.55 amu

If the atomic mass of hydrogen is 1.001, explain the percent abundance of the hydrogen- 1 and hydrogen- 2 isotopes.

hydrogen- 1 is the most abundant

Estimate the percent abundances for the following isotopes of phosphorus: phosphorus- 31, phosphorus- 29.

phospohorus-31 would be much more abundant than phosphorus- 29

Calculate the atomic mass of bromine. The two isotopes of bromine have atomic masses and relative abundance of 79.92 amu (50.69%) and 80.92 amu (49.31%).

79.90 amu

Boron- 11 has two isotopes: boron- 10 and boron-11. Which is more abundant, given that the atomic mass of boron is 10.81 amu.

boron- 11