Ch 3 Worksheet #4 Name______

Convert each of the following using the factor-label method.

1. 0.15 moles Cu to atoms

2. 75.0 g Zn to moles Zn

3. 2.55  1012 atoms Ca to grams

4. 10.0 g Na to atoms

5. 0.100 moles Bi to grams

6. 1.204 × 1023 atoms Ag to grams

7. How many helium atoms would have the same mass as 6.00  1015 carbon atoms? 8. Cesium consists of three natural isotopes. Calculate the % abundance to four significant figures, the exact isotopic mass to six significant figures and the mass number of the other isotope.

exact % abundance isotope isotopic mass (amu)

80.62 133Cs 132.9137 8.43 134Cs 133.9281

Determine the number of subatomic particles in each of the following:

9. 91Sr+2 protons = electrons = neutrons = mass # =

10. Potassium-42 protons = electrons = neutrons = mass # =

11. Write the chemical symbol for the element that has 95 protons and 89 electrons.

12. Write the complete atomic symbol for the ion with 73 protons, 108 neutrons, and 68 electrons. 13. Samples of an unknown element X were collected and their masses were recorded. Use the information presented in the data table to answer the following questions.

Isotope Isotopic Mass (amu) % abundance Mass Number 1 235.043 924 0.720 2 238.050 784 99.280

a) Fill in the mass number for each sample of element X in the data table.

b) What is the most common isotope of element X?

c) Calculate the average atomic mass of element X to 5 significant figures.

d) Use your periodic table to identify element X based on its average atomic mass. What is the atomic number and symbol of this element?