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- Refer to a periodic table. Which pair of elements do you expect to be most similar in their chemical properties? (LO 2.3) (a) K and Cu (b) O and Se (c) Be and B (d) Rb and Sr
Problem 1
- Identify the location of the element in period 4, group 6A and classify it as a metal, nonmetal, or semimetal. (LO 2.2) (a) Element in position a; nonmetal (b) Element in position b; metal (c) Element in position c; semimetal (d) Element in position d; metal
Problem 2
- Which description of an element is incorrectly matched with its location in the periodic table? (LO 2.5–2.6)
Problem 3
(a) Element 3—An element in the transition metal group that is a good conductor of electricity. (b) Element 2—An element that is in the halogen group and does not conduct electricity. (c) Element 4—An element in alkali metal group that is found in its pure form in nature. (d) Element 1—An element that is a solid at room tempera-ture, brittle, and a poor conductor of electricity.
- A compound containing sulfur and fluorine contains 8.00 g of S and 9.50 g of F. Which combination of S and F masses represents a different compound that obeys the Law of Mul-tiple Proportions? (LO 2.8) (a) 32.0 g of S and 38.0 g of F (b) 4.00 g of S and 4.75 g of F (c) 8.00 g of S and 10.5 g of F (d) 16.0 g of S and 57.0 g of F
Problem 4
- Which experiment and subsequent observation led to the discovery that atoms contain negatively charged particles, now known as electrons? (LO 2.10–2.12) (a) Oil is sprayed into a chamber and the speed at which the oil droplets fall is measured with and without an applied voltage. X rays in the chamber knock electrons out of air molecules. The electrons stick to the oil pro-ducing an overall negative charge on the drops. Adjusting the voltage changes the speed at which the negatively charged oil droplets fall. (b) When a high voltage is applied across metal electrodes at opposite ends of a sealed glass tube, a cathode ray is produced. The cathode ray is repelled by a negatively charged plate. (c) A radioactive substance emits alpha particles, which are directed at a thin gold foil. Most of the alpha par-ticles pass through the foil, but a few alpha particles are slightly deflected and some even bounce back toward the radioactive source. (d) The mass of different elements in a pure chemical com-pound are measured. Different samples of the compound always contains the same proportion of elements by mass.
Problem 5
- How many protons, neutrons, and electrons are present in an atom of 2 206Pb? (LO 2.14) (a) 82 protons, 206 neutrons, 82 electrons (b) 124 protons, 82 neutrons, 124 electrons (c) 82 protons, 124 neutrons, 82 electrons (d) 82 protons, 82 neutrons, 124 electrons
Problem 6
- What is the atomic weight of an element that consists of two naturally occurring isotopes? The first isotope has a mass of 84.911 and an abundance of 72.17% and the second isotope has a mass of 86.909 and an abundance of 27.83%. (LO 2.15) (a) 85.47 (b) 86.35 (c) 85.91 (d) 85.17
Problem 7
- Which sample has the greatest mass? (LO 2.16) (a) 5.5 mol of C (b) 2.1 mol of S (c) 4.2 mol of Be (d) 0.52 mol of Ag
Problem 8
- How many atoms are present in 1.2 g of gold? (LO 2.16) (a) 2.5 * 1021 (b) 1.4 * 1026 (c) 7.2 * 1023 (d) 3.7 * 1021
Problem 9
Problem 10
Bromine has two naturally occurring isotopes; 79Br (mass of 78.918) and 81Br (mass of 80.916). If the atomic weight of bromine is 79.904, predict the mass spectrum of a sample of bromine atoms. (LO 2.17) (a)
(b)
(c)
(d)
Problem 11
The molecular illustration represents (LO 2.18) (a) a pure element (b) a mixture of two elements (c) a pure compound (d) a mixture of an element and a compound
Problem 12
Which of the following compounds would you expect to have covalent bonds? (LO 2.20) (a) Na2O (b) PBr3 (c) CaBr2 (d) MgS
- How many protons, neutrons, and electrons are in 107Ag+? (LO 2.21) (a) protons = 47, neutrons = 60, electrons = 46 (b) protons = 47, neutrons = 107, electrons = 48 (c) protons = 60, neutrons = 47, electrons = 47 (d) protons = 47, neutrons = 107, electrons = 46
Problem 13
Problem 14
What is the correct formula for sodium phosphate? (LO 2.24) (a) Na3PO4 (b) Na3P (c) NaPO4 (d) Na(PO4)2
- Where on the following outline of a periodic table are the indicated elements or groups of elements?
Problem 34
(a) Alkali metals (b) Halogens (c) Alkaline earth metals (d) Transition metals (e) Hydrogen (f) Helium
Problem 35a
Is the red element on the following periodic table likely to be a gas, a liquid, or a solid?
Problem 35b
What is the atomic number of the blue element?
Problem 35c
What is the group number of the green, blue, and red elements?
Problem 35d
Name at least one other element that is chemically similar to the green element.
- The element indicated on the following periodic table is used in smoke detectors. Identify it, give its atomic number, and tell what kind of group it's in.
Problem 36
Problem 37a
Identify the three elements indicated on the periodic table, and give the group that they are in.
Problem 37b
Classify these elements as metals, nonmetals, or semimetals.
Problem 37c
Would you expect these elements to have similar or different chemical reactivity?
Problem 38
If yellow spheres represent sulfur atoms and red spheres represent oxygen atoms, which of the following drawings shows a collection of sulfur dioxide (SO2) units?
(a)
(b)
(c)
(d)
- Assume that the mixture of substances in drawing (a) undergoes a reaction. Which of the drawings (b)–(d) rep-resents a product mixture consistent with the law of mass conservation?
Problem 39
(b)
(c)
(d) - In the following drawings, red spheres represent protons, and blue spheres represent neutrons. Which of the draw-ings represent different isotopes of the same element, and which represents a different element altogether? (a)
Problem 40
(b)
(c) Problem 41a
Which of the following three drawings represents a neutral Na atom? (a) (b) (c)
Problem 41b
Which represents a Ca atom with two positive electrical charges (Ca2+)? (a)
(b)
(c)
Problem 41c
Which represents an F atom with one minus charge (F-)? (a)
(b)
(c)
Problem 42
In the following drawings, red and blue spheres represent atoms of different elements. Match the molecular pictures (a)–(c) with the following descriptions: (i) a pure substance consisting of a compound (ii) a pure substance consisting of an element (iii) a mixture of element