Chapter 2

Which of the following is true about an individual atom? Explain. a. An individual atom should be considered to be a solid. b. An individual atom should be considered to be a liquid. c. An individual atom should be considered to be a gas. d. The state of the atom depends on which element it is. e. An individual atom cannot be considered to be a solid, liquid, or gas. Justify your choice, and for choices you did not pick, explain what is wrong with them.

How would you go about finding the number of "chalk molecules" it takes to write your name on the board? Provide an explanation of all you would need to do and a sample calculation.

Heat is applied to an ice cube in a closed container until only steam is present. Draw a representation of this process, assuming you can see it at an extremely high level of magnification. What happens to the size of the molecules? What happens to the total mass of the sample?

The formula of water is \(\mathrm{H}_{2} \mathrm{O}\). Which of the following is indicated by this formula? Explain your answer. a. the mass of hydrogen is twice that of oxygen in each molecule. b. there are two hydrogen atoms and one oxygen atom per water molecule. c. the mass of oxygen is twice that of hydrogen in each molecule. d. there are two oxygen atoms and one hydrogen atom per water molecule.

You may have noticed that when water boils, you can see bubbles that rise to the surface of the water. Which of the following is inside these bubbles? Explain. a. air b. hydrogen and oxygen gas c. oxygen gas d. water vapor e. carbon dioxide gas

One of the best indications of a useful theory is that it raises more questions for further experimentation than it originally answered. Does this apply to Dalton's atomic theory? Give examples.

Dalton assumed that all atoms of the same element were identical in all their properties. Explain why this assumption is not valid.

Evaluate each of the following as an acceptable name for water: a. dihydrogen oxide c. hydrogen hydroxide b. hydroxide hydride d. oxygen dihydride

Why do we call \(\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}\) barium nitrate, but we call \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{2}\) iron(II) nitrate?

Why is calcium dichloride not the correct systematic name for \(\mathrm{CaCl}_{2} ?\)

The common name for \(\mathrm{NH}_{3}\) is ammonia. What would be the systematic name for \(\mathrm{NH}_{3}\) ? Support your answer.

Which (if any) of the following can be determined by knowing the number of protons in a neutral element? Explain your answer. a. the number of neutrons in the neutral element. b. the number of electrons in the neutral element. c. the name of the element.

Which of the following explain how an ion is formed? Explain your answer. a. adding or subtracting protons to/from an atom. b. adding or subtracting neutrons to/from an atom. c. adding or subtracting electrons to/from an atom.

When hydrogen is burned in oxygen to form water, the composition of water formed does not depend on the amount of oxygen reacted. Interpret this in terms of the law of definite proportion.

The two most reactive families of elements are the halogens and the alkali metals. How do they differ in their reactivities?

Explain the law of conservation of mass, the law of definite proportion, and the law of multiple proportions.

Section \(2.3\) describes the postulates of Dalton's atomic theory With some modifications, these postulates hold up very well regarding how we view elements, compounds, and chemical reactions today. Answer the following questions concerning Dalton's atomic theory and the modifications made today. a. The atom can be broken down into smaller parts. What are the smaller parts? b. How are atoms of hydrogen identical to each other and how can they be different from each other? c. How are atoms of hydrogen different from atoms of helium? How can \(\mathrm{H}\) atoms be similar to \(\mathrm{He}\) atoms? d. How is water different from hydrogen peroxide \(\left(\mathrm{H}_{2} \mathrm{O}_{2}\right)\) even though both compounds are composed of only hydrogen and oxygen? e. What happens in a chemical reaction and why is mass conserved in a chemical reaction?

The contributions of J. J. Thomson and Ernest Rutherford led the way to today's understanding of the structure of the atom. What were their contributions?

What is the modern view of the structure of the atom?

The number of protons in an atom determines the identity of the atom. What does the number and arrangement of the electrons in an atom determine? What does the number of neutrons in an atom determine?

If the volume of a proton is similar to the volume of an electron, how will the densities of these two particles compare to each other?

For lighter, stable isotopes, the ratio of the mass number to the atomic number is close to a certain value. What is the value? What happens to the value of the mass number to atomic number ratio as stable isotopes become heavier?

List some characteristic properties that distinguish the metallic elements from the nonmetallic elements.

Consider the elements of Group \(4 \mathrm{~A}\) (the "carbon family"): \(\mathrm{C}, \mathrm{Si}\), Ge, \(\mathrm{Sn}\), and \(\mathrm{Pb}\). What is the trend in metallic character as one goes down this group? What is the trend in metallic character going from left to right across a period in the periodic table?

Distinguish between the following terms. a. molecule versus ion b. covalent bonding versus ionic bonding c. molecule versus compound d. anion versus cation

Which of the following statements are true? For the false statements, correct them. a. Most of the known elements are metals. b. Element 118 should be a nonmetal. c. Hydrogen has mostly metallic properties. d. A family of elements is also known as a period of elements. e. When an alkaline earth metal, A, reacts with a halogen, X. the formula of the covalent compound formed should be \(\mathrm{A}_{2} \mathrm{X}\).

When mixtures of gaseous \(\mathrm{H}_{2}\) and gaseous \(\mathrm{Cl}_{2}\) react, a product forms that has the same properties regardless of the relative amounts of \(\mathrm{H}_{2}\) and \(\mathrm{Cl}_{2}\) used. a. How is this result interpreted in terms of the law of definite proportion? b. When a volume of \(\mathrm{H}_{2}\) reacts with an equal volume of \(\mathrm{Cl}_{2}\) at the same temperature and pressure, what volume of product having the formula \(\mathrm{HCl}\) is formed?

A reaction of 1 liter of chlorine gas \(\left(\mathrm{Cl}_{2}\right)\) with 3 liters of fluorine gas \(\left(\mathrm{F}_{2}\right)\) yields 2 liters of a gaseous product. All gas volumes are at the same temperature and pressure. What is the formula of the gaseous product?

In a combustion reaction, \(46.0 \mathrm{~g}\) of ethanol reacts with \(96.0 \mathrm{~g}\) of oxygen to produce water and carbon dioxide. If \(54.0 \mathrm{~g}\) of water is produced, what mass of carbon dioxide is produced?

A sample of chloroform is found to contain \(12.0 \mathrm{~g}\) of carbon, \(106.4 \mathrm{~g}\) of chlorine, and \(1.01 \mathrm{~g}\) of hydrogen. If a second sample of chloroform is found to contain \(30.0 \mathrm{~g}\) of carbon, what is the total mass of chloroform in the second sample?

Hydrazine, ammonia, and hydrogen azide all contain only nitrogen and hydrogen. The mass of hydrogen that combines with \(1.00 \mathrm{~g}\) of nitrogen for each compound is \(1.44 \times 10^{-1} \mathrm{~g}, 2.16 \times\) \(10^{-1} \mathrm{~g}\), and \(2.40 \times 10^{-2} \mathrm{~g}\), respectively. Show how these data illustrate the law of multiple proportions.

Consider \(100.0-\mathrm{g}\) samples of two different compounds consisting only of carbon and oxygen. One compound contains \(27.2 \mathrm{~g}\) of carbon and the other has \(42.9 \mathrm{~g}\) of carbon. How can these data support the law of multiple proportions if \(42.9\) is not a multiple of \(27.2\) ? Show that these data support the law of multiple proportions.

Indium oxide contains \(4.784 \mathrm{~g}\) of indium for every \(1.000 \mathrm{~g}\) of oxygen. In 1869 , when Mendeleev first presented his version of the periodic table, he proposed the formula \(\mathrm{In}_{2} \mathrm{O}_{3}\) for indium oxide. Before that time it was thought that the formula was InO. What values for the atomic mass of indium are obtained using these two formulas? Assume that oxygen has an atomic mass of \(16.00\).

From the information in this chapter on the mass of the proton, the mass of the electron, and the sizes of the nucleus and the atom, calculate the densities of a hydrogen nucleus and a hydrogen atom.

In an experiment it was found that the total charge on an oil drop was \(5.93 \times 10^{-18} \mathrm{C}\). How many negative charges does the drop contain?

A chemist in a galaxy far, far away performed the Millikan oil drop experiment and got the following results for the charges on various drops. Use these data to calculate the charge of the electron in zirkombs. \(2.56 \times 10^{-12}\) zirkombs \(\quad 7.68 \times 10^{-12}\) zirkombs \(3.84 \times 10^{-12}\) zirkombs \(\quad 6.40 \times 10^{-13}\) zirkombs

What are the symbols of the following metals: sodium, radium, iron, gold, manganese, lead.

What are the symbols of the following nonmetals: fluorine, chlorine, bromine, sulfur, oxygen, phosphorus?

Give the names of the metals that correspond to the following symbols: \(\mathrm{Sn}, \mathrm{Pt}, \mathrm{Hg}, \mathrm{Mg}, \mathrm{K}, \mathrm{Ag}\).

Give the names of the nonmetals that correspond to the following symbols: As, I, Xe, He, C, Si.

a. Classify the following elements as metals or nonmetals: $$ \begin{array}{lll} \mathrm{Mg} & \mathrm{Si} & \mathrm{Rn} \\ \mathrm{Ti} & \mathrm{Ge} & \mathrm{Eu} \\ \mathrm{Au} & \mathrm{B} & \mathrm{Am} \\ \mathrm{Bi} & \mathrm{At} & \mathrm{Br} \end{array} $$ b. The distinction between metals and nonmetals is really not a clear one. Some elements, called metalloids, are intermediate in their properties. Which of these elements would you reclassify as metalloids? What other elements in the periodic table would you expect to be metalloids?

a. List the noble gas elements. Which of the noble gases has only radioactive isotopes? (This situation is indicated on most periodic tables by parentheses around the mass of the element. See inside front cover.) b. Which lanthanide element and which transition element have only radioactive isotopes?

Identify the elements that correspond to the following atomic numbers. Label each as either a noble gas, a halogen, an alkali metal. an alkaline earth metal, a transition metal, a lanthanide metal, or an actinide metal. a. 17 e. 2 b. 4 f. 92 c. 63 g. 55 d. 72

How many protons and neutrons are in the nucleus of each of the following atoms? In a neutral atom of each element, how many electrons are present? a. \(^{7 y} B r\) d. \({ }^{133} \mathrm{Cs}\) b. \({ }^{\text {st }} \mathrm{Br}\) e. \({ }^{3} \mathrm{H}\) c. \({ }^{239} \mathrm{Pu}\). f. \({ }^{56} \mathrm{Fe}\)

What number of protons and neutrons are contained in the nucleus of each of the following atoms? Assuming each atom is uncharged, what number of electrons are present? a. \({ }_{12}^{235} \mathrm{U}\) d. \(\frac{200}{82} \mathrm{~Pb}\) b. \({ }_{6}^{13} \mathrm{C} \quad\) e. \(\frac{86}{37} \mathrm{Rb}\) c. \({ }_{20}^{5} \mathrm{Fe}\) f. \({ }_{20} \mathrm{Ca}\)

Write the atomic symbol \(\left({ }_{Z}^{A} X\right)\) for each of the following isotopes. a. \(Z=8\), number of neutrons \(=9\) b. the isotope of chlorine in which \(A=37\) c. \(Z=27, A=60\) d. number of protons \(=26\), number of neutrons \(=31\) e. the isotope of \(I\) with a mass number of 131 f. \(Z=3\), number of neutrons \(=4\)

Write the atomic symbol \(\left({ }_{z}^{A} X\right)\) for each of the isotopes described below. a. number of protons \(=27\), number of neutrons \(=31\) b. the isotope of boron with mass number 10 c. \(Z=12, A=23\) d. atomic number 53, number of neutrons \(=79\) e. \(Z=9\), number of neutrons \(=10\) f. number of protons \(=29\), mass number 65

For each of the following ions, indicate the number of protons and electrons the ion contains. a. \(\mathrm{Ba}^{2+}\) e. \(\mathrm{Co}^{3}\) b. \(\mathrm{Zn}^{2+}\) f. \(\mathrm{Te}^{2}\) c. \(\mathrm{N}^{3-} \quad\) g. \(\mathrm{Br}^{-}\) d. \(\mathrm{Rb}^{+}\)

How many protons, neutrons, and electrons are in each of the following atoms or ions? a. \({ }_{12}^{24} \mathrm{Mg}\) b. \({ }_{12}^{24} \mathrm{Mg}^{2+}\) c. \({ }_{27}^{59} \mathrm{Co}^{2+}\) d. \({ }_{27}^{59} \mathrm{Co}^{3+}\) e. \({ }_{27}^{59} \mathrm{Co}\) f. \({ }_{34}^{74} \mathrm{Se}\) g. \({ }_{34} \mathrm{Se}^{2}\). h. \(\frac{63}{28} \mathrm{Ni}\) i. \(\frac{59}{28} \mathrm{Ni}^{2+}\)

What is the symbol for an ion with 63 protons, 60 electrons, and 88 neutrons? If an ion contains 50 protons, 68 neutrons, and 48 electrons, what is its symbol?