Chapter 3 - Atomic Theory Problem Set Answer PDF

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Answers to problems that are similar to the book to help you practice and understand the concepts....

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CHEM 1140: Ch. 3 Problem Set 1. Write the symbols or element names for the following: a. Mg magnesium e. iron b. K

potassium

f. copper

c. fluorine

F

d. Pb lead

d. argon

Ar

e. Au gold

Fe Cu

2. What is the difference between Hf and HF? Hf is the elemental symbol for the element hafnium. HF is the formula for the molecular compound hydrogen fluoride. 3. Write the formulas for the following molecular compounds: a. Sulfur dioxide (one sulfur and two oxygen atoms) SO2 b. Phosphorous trichloride (one phosphorous and three chlorine atoms)

PCl3

4. Write the formulas for the following ionic compounds: a. Iron (II) sulfate (one Fe2+ ion and one SO42- ion) FeSO4 b. Calcium hypochlorite (one Ca2+ ion and two ClO- ions) Ca(ClO)2 5. Summarize the major points of Dalton’s atomic theory. 1. Matter is composed of small, indivisible particles called atoms. (Now know that atoms can be further divided into protons, neutrons, and electrons, and further (quarks)) 2. Atoms of the same element are identical and have the same properties, different elements have fundamentally different atoms (not entirely true-isotopes). 3. Chemical compounds are composed of atoms of different elements combined in small whole-number ratios. 4. Chemical reactions are merely the rearrangement of atoms into different combinations. 6. Which of the following describes an electron? a neutron? a proton? a. +1 charge, mass 0 amu b. +1 charge, mass 1 amu c. -1 charge, mass 0 amu d. -1 charge, mass 1 amu e. 0 charge, mass 0 amu f. 0 charge, mass 1 amu electron = c, neutron = f, proton = b 7. Give the number of protons, electrons, and neutrons in each of the following isotopes: a. 90Sr 38 p, 38 e, 52 n 235 b. U 92 p, 92 e, 143 n c. 60Ni 28 p, 28 e, 32 n 8. Give the total number of protons and electrons in the following: a. Al3+ 13 p, 10 e b. Br 35 p, 36 e

1

9. Write the element symbol and the charge for the following ions: a. 50 protons and 48 electrons Sn2+ b. 53 protons and 54 electrons I 10. Bromine is composed of 50.5% 79Br (isotopic mass of 78.92 amu) and 49.5% 81Br (isotopic mass of 80.92 amu). What is the atomic mass of the element? (0.505 x 78.92 amu) + (0.495 x 80.92 amu) = 80.0 amu 11. Categorize the following as 1) intermetallics, 2) ionic compounds, or 3) molecular substances. a. ZnCl2 (2) b. SF6 (3) c. Ag3Sn (1) d.H2 (3) f. KNO3 (2)

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