Name_______________________________ Atoms Worksheet #2 (The Mole) 1. Counting Atoms – How many atoms are in the following compounds? a) CaCl2___3____ b) NH4OH___7____ c) NaCl____2___ d) N2O7__9_____ e) P2O5__7_____ f) KNO3___5____ g) Al2(CO3)3__14_____ h) Na3PO4__8___ i) Mg(NO3)2__9_____ 2. Calculate the molar mass of the following compounds: a) NaCl 58.5 g/mol b) Fe2O3 159.6 g/mol c) LiOH 23.9 g/mol d) NH3 17.0 g/mol e) AlPO4 122.3 g/mol 3. Mole-to-Gram/Gram-to-Mole Conversions (One Step Problems) a) How many grams of Ca are present in 3.28 moles? 132 g Ca b) How many grams of S are present in 5.39 moles? 173 g S c) How many moles of Ag are there in 4.98 gram? 0.0462 mol d) How many moles of Mg are present in 303 grams? 12.5 mol Mg 4. Conversions using Avogadro’s number (One Step Problems) a) How many atoms are present in 34.69 moles of Mg? 2.09 X 1025 atoms b) How many atoms are present in 0.529 moles of Li? 3.18 X 1023 atoms c) How many moles of Mn are present in 4.09 x 1024 atoms of Mn? 6.79 mol d) How many moles of Ni are present in 5.88 x 1019 atoms? 0.0000977 mol 5. Grams ↔ Moles ↔ Particles OR Atoms OR Molecules (Two Step Problems) a) Calculate the number of molecules in 8.33 grams of O2 1.57 X 1023 molecules b.) Calculate the number of atoms in 43.33 grams of iron, Fe? 4.67 X 1023 atoms c) Calculate the number of particles in 32.8 grams of Cu2S. 4.12 X 1020 particles e) Calculate the number of grams of lithium in 5.44 x 1021 atoms of lithium. 0.0624 g 25 f) Calculate the number of grams of SO3 in 3.92 x 10 molecules of sulfur trioxide. 5220 g (rounded to 3 sig figs) Name______________________________ Atoms Worksheet #3 (More Practice Problems) SHOW ALL WORK USING DIMENSIONAL ANALYSIS!!!!! l. Calculate the following: a. molecules in 5.00 moles of nitrogen gas b. molecules in 8.78 moles of oxygen gas c. atoms in 4.89 moles of calcium d. atoms in 6.0 moles of nitrogen gas 2. Calculate the number of grams represented by the following: a. 3.0l X l023 atoms of sodium b. l.20 X l024 atoms of sulfur 26 c. l.44 X l0 molecules of carbon dioxide CO2 3. How many atoms are in 2.73 X l0-2 moles of magnesium? 24 4. How many moles of SO3 are in 2.4 X l0 molecules of SO3? 5. The chemical formula for aspirin is C9H8O4. What is the mass in grams of 0.40 moles of aspirin? 6. 65.3 grams of lithium would contain how many atoms of lithium? 7. A sample of potassium contains 7.00X1026 atoms of potassium. What is the mass in grams of this sample? Atoms Test Review Read (and understand) notes and be able to complete all mole problems from the Atoms Worksheets. 1.__54___How many neutrons in an atom with an atomic number of 42 and mass number of 96. 2.__80___How many electrons are present in an atom of mercury-201? 3.__9___Calculate the number of protons in an atom with a mass number of 19 and 10 neutrons. 4.___33__How many electrons are in an atom with a mass number of 75 and 42 neutrons. 5. How did the results of the gold foil experiment lead Rutherford to recognize the existence of the atomic nuclei? 6. Explain why atoms are neutral. Equal number of protons and electrons 7.___electron__Which has less mass: an electron or a proton? 8. What information about an atom is provided by the atoms atomic number? The atoms mass number? Atomic number = number of protons mass number = protons + neutrons 9. Write the complete nuclear symbols for isotopes of uranium that have 142 neutrons, 143 neutrons, and 146 neutrons. U-234 U-235 U-238 10. _____Write the nuclear symbol and hyphen notation for two isotopes of carbon. Both isotopes have six protons. One isotope has six neutrons, while the other has seven neutrons. C-13 C-14 11._____All barium atoms have 56 protons. One isotope of barium has 74 neutrons, and another isotope has 81 neutrons. Write the nuclear symbols for these two isotopes of barium. Ba – 130 Ba - 137 12._____Precidt which isotope of nitrogen is more commonly found, nitrogen-14 or nitrogen-15. N-14 14. Explain why different atoms of the same element always have the same atomic number but can have different mass numbers. They have different # of neutrons 15. What is an ion? 16. What are the charges of an electron, a proton, and a neutron? e = -1 p = +1 n = 0 17. State the law of conservation of mass, law of determine proportions, and law of multiple proportions. 18. Calculate the average atomic mass for each of the following elements assuming that each consists of the isotopic mixture shown. (A) 99.76% Oxygen-16, 0.04% Oxygen-17, 0.20% Oxygen-18 16.044 g/mol (B) 51.83% Silver-107, 48.175 Silver-109 107.96885 g/mol 19. Understand the modern atomic theory including Daltons’ Postulates, Thomson’s discovery of electron properties, Rutherford’s nuclear atom, and Bohr’s nuclear atom. .