Chemistry--Chapter 5: Atomic Structure and the Periodic Table

1 Chemistry-- unit 1: Atomic Structure and the Periodic Table Practice Problems I. Atoms 1) 100,000,000 copper atoms would form a line 1 cm long. How long would a line formed by 1 x 107 copper atoms be? Express your answer in millimeters. mmatomsCummatomsCu?1011010178 mm1? II. Structure of the Atom 2) A sulfur-32 atom contains 16 protons, 16 neutrons, and 16 electrons. What is the mass, in grams, of a sulfur-32 atom? + 16 10 24 g 16 10 24 g 32 10 24 g 16 10 24 g or 16 10 24 g or 16 10 28 g 16 10 28 g (electrons negligible) 10 23 g 10 23 g 10 23 g 3) What is the mass in grams of a lithium-7 atom?

2 + 3 10 24 g 3 10 24 g 7 10 24 g 4 10 24 g or 4 10 24 g or 3 10 28 g 3 10 28 g (electrons negligible) 10 23 g 10 23 g 10 23 g 4) The mass of a neutron is x 10 24 g. Approximately what number of neutrons would equal a mass of one gram? neutronsgramneutrongrams? III. Distinguishing Between Atoms 5) How many protons are found in an atom of each of the following? a. boron (5) b. sulfur (16) c. neon (10) d. lithium (3) 6) Complete the Table for the following elements: Chemistry-- unit 1: Atomic Structure and the Periodic Table Practice Problems Element Name Number of Protons Number of Electrons Number of Neutrons Atomic Number Mass Number Element Symbol Manganese 25 25 30 25 55 Mn5525 Sodium 11 11 12 11 23 Na2311 Bromine 35 35 45 35 80 Br8035 Yttrium 39 39 50 39 89 Y8939 Arsenic 33 33 42 33 75 As7533 Actinium 89 89 138 89 227 Ac22789 7) How many neutrons are in each atom?

3 A. 23Na (12) b. 238U (146) c. 81Br (46) d. 19F (10) 8) The two most abundant isotopes of carbon are carbon-12 (mass = amu) and carbon-13 (mass = amu). Their relative abundances are and , respectively. Calculate the Atomic mass of carbon. = + = 100 = amu s or 9) Element X has two isotopes: X-100 and X-104. If the Atomic mass of X is 101 amu, what is the relative abundance of each isotope in nature? 100 A = ? + 104 B = ? 10,100 100 = 101 amu s or or, more mathy , 100A + 104B = 10,100 One equation with two unknowns, solve with substitution, but need a second equation.

4 A and B are percentages in nature of element 101, so A + B must = 100 (or 100 B = A). So, 100(100 B) + 104B = 10,100 10,000 100B + 104B = 10,100 4B = 100 B = 25%, A = 75% Chemistry-- unit 1: Atomic Structure and the Periodic Table Practice Problems *Note that guess and check will also work to solve this problem, but will take much longer! IV. The Periodic Table : Organizing the Elements 10) Which element below should have chemical properties similar to fluorine (F)? a. Li b. Si c. Br (c. Br in same chemical family on Periodic Table ) d. Ne 11) Identify each element as a metal, metalloid, or nonmetal.

5 A. fluorine (nonmetal) b. germanium (metalloid) c. zinc (metal) d. phosphorus (nonmetal) e. lithium (metal) 12) Which of the following is not a transition metal? a. magnesium (a. Magnesium) b. titanium c. chromium d. mercury 13) Name two elements that have properties similar to those of the element potassium. (Any 2 of lithium, sodium, rubidium, cesium, francium) 14) All elements of the Periodic Table can be divided into three broad classes. What are these classes and how do they differ? (metals, nonmetals, metalloids) MMEETTAALLSS NNOONNMMEETTAALLSS ggoooodd ccoonndduuccttoorrss ooff hheeaatt aanndd eelleeccttrriicciittyy ppoooorr ccoonndduuccttoorrss ooff hheeaatt aanndd eelleeccttrriicciittyy sshhiinnyy iinn aappppeeaarraannccee ((hhaavvee lluusstteerr)) dduullll iinn aappppeeaarraannccee ((llaacckk lluusstteerr))

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