Unit 2 Lesson 4 Practice

1) What is the average atomic mass of Barium (atomic number 56) (unit=amu)

• 56

• 137.33

2) What is the average atomic mass of Lithium?

• 3
• 6.94 amu

3) What is the most stable and common isotope of Lithium?

• Lithium-6
• Lithium-7

4) What is the average atomic mass of Nitrogen?

• 7
• 14.007 amu

5) What is the most stable and common isotope of Nitrogen?

• Nitrogen-14
• Nitrogen-15

6) An isotope of iron has 26 protons, 30 neutrons, and 26 electrons. What is its mass number? (mass number=protons+neutrons)

7) An isotope of oxygen has 8 protons, 9 neutrons, and 8 electrons. What is its mass number? (mass number=protons+neutrons)

8) How many neutrons are in an atom of Beryllium-9 (Beryllium has 4 protons)? neutrons= mass number - protons

9) How many neutrons are in an atom of Carbon-12 (Carbon has 6 protons)? neutrons= mass number - protons