Chapter 2

Give the names and charges of the cation and anion in each of the following compounds: (a) CuS, (b) \(\mathrm{Ag}_{2} \mathrm{SO}_{4}\), (c) \(\mathrm{Al}\left(\mathrm{ClO}_{3}\right)_{3}\), (d) \(\mathrm{Co}(\mathrm{OH})_{2}\), \((\mathrm{e}) \mathrm{PbCO}_{3}\)

Name the following ionic compounds: (a) \(\mathrm{MgO}\), (b) \(\mathrm{AlCl}_{3}\), (c) \(\mathrm{Li}_{3} \mathrm{PO}_{4}\), (d) \(\mathrm{Ba}\left(\mathrm{ClO}_{4}\right)_{2}\), (e) \(\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}\) (f) \(\mathrm{Fe}(\mathrm{OH})_{2},(\mathrm{~g}) \mathrm{Ca}\left(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)_{2}\), (h) \(\mathrm{Cr}_{2}\left(\mathrm{CO}_{3}\right)_{3}\), (i) \(\mathrm{K}_{2} \mathrm{CrO}_{4}\) (j) \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}\)

Name the following ionic compounds: (a) \(\mathrm{K}_{2} \mathrm{O}\), (b) \(\mathrm{NaClO}_{2}\), (c) \(\mathrm{Sr}(\mathrm{CN})_{2}\), (d) \(\mathrm{Co}(\mathrm{OH})_{2}\), (e) \(\mathrm{Fe}_{2}\left(\mathrm{CO}_{3}\right)_{3}\) (f) \(\mathrm{Cr}\left(\mathrm{NO}_{3}\right)_{3},(\mathrm{~g})\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{3}\), (h) \(\mathrm{NaH}_{2} \mathrm{PO}_{4}\), (i) \(\mathrm{KMnO}_{4}\) (j) \(\mathrm{Ag}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\)

Write the chemical formulas for the following compounds: (a) aluminum hydroxide, (b) potassium sulfate, (c) copper(I) oxide, (d) zinc nitrate, (e) mercury(II) bromide, (f) iron(III) carbonate, (g) sodium hypobromite.

Give the chemical formula for each of the following ionic compounds: (a) sodium phosphate, (b) zinc nitrate, (c) barium bromate, (d) iron(II) perchlorate, (e) cobalt(II) hydrogen carbonate, (f) chromium(III) acetate, \((\mathrm{g})\) potassium dichromate.

Give the name or chemical formula, as appropriate, for each of the following acids: (a) \(\mathrm{HBrO}_{3}\), (b) \(\mathrm{HBr}\), (c) \(\mathrm{H}_{3} \mathrm{PO}_{4}\), (d) hypochlorous acid, \((\mathrm{e})\) iodic acid, \((\mathrm{f})\) sulfurous acid.

Provide the name or chemical formula, as appropriate, for each of the following acids: (a) hydrobromic acid, (b) hydrosulfuric acid, (c) nitrous acid, (d) \(\mathrm{H}_{2} \mathrm{CO}_{3}\), (e) \(\mathrm{HClO}_{3}\), (f) \(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\).

Give the name or chemical formula, as appropriate, for each of the following binary molecular substances: (a) \(\mathrm{SF}_{6}\), \((\mathrm{b}) \mathrm{IF}_{5}\), (c) \(\mathrm{XeO}_{3}\), (d) dinitrogen tetroxide, (e) hydrogen cyanide, (f) tetraphosphorus hexasulfide.

The oxides of nitrogen are very important components in urban air pollution. Name each of the following compounds: (a) \(\mathrm{N}_{2} \mathrm{O},(\mathrm{b}) \mathrm{NO},(\mathrm{c}) \mathrm{NO}_{2},(\mathrm{~d}) \mathrm{N}_{2} \mathrm{O}_{5},(\mathrm{e}) \mathrm{N}_{2} \mathrm{O}_{4}\)

Write the chemical formula for each substance mentioned in the following word descriptions (use the front inside cover to find the symbols for the elements you don't know). (a) Zinc carbonate can be heated to form zinc oxide and carbon dioxide. (b) On treatment with hydrofluoric acid, silicon dioxide forms silicon tetrafluoride and water. (c) Sulfur dioxide reacts with water to form sulfurous acid. (d) The substance phosphorus trihydride, commonly called phosphine, is a toxic gas. (e) Perchloric acid reacts with cadmium to form cadmium(II) perchlorate. (f) Vanadium(III) bromide is a colored solid.

Assume that you encounter the following sentences in your reading. What is the chemical formula for each substance mentioned? (a) Sodium hydrogen carbonate is used as a deodorant. (b) Calcium hypochlorite is used in some bleaching solutions. (c) Hydrogen cyanide is a very poisonous gas. (d) Magnesium hydroxide is used as a cathartic. (e) Tin(II) fluoride has been used as a fluoride additive in toothpastes. (f) When cadmium sulfide is treated with sulfuric acid, fumes of hydrogen sulfide are given off.

(a) What is a hydrocarbon? (b) Butane is the alkane with a chain of four carbon atoms. Write a structural formula for this compound, and determine its molecular and empirical formulas.

(a) What ending is used for the names of alkanes? (b) Hexane is an alkane whose structural formula has all its carbon atoms in a straight chain. Draw the structural formula for this compound, and determine its molecular and empirical formulas. (Hint: You might need to refer to Table 2.6.)

(a) What is a functional group? (b) What functional group characterizes an alcohol? (c) With reference to Exercise \(2.75\), write a structural formula for 1 -butanol, the alcohol derived from butane, by making a substitution on one of the end carbon atoms.

(a) What do ethane and ethanol have in common? (b) How does 1-propanol differ from propane?

Describe a major contribution to science made by each of the following scientists: (a) Dalton, (b) Thomson, (c) Millikan, (d) Rutherford.

How did Rutherford interpret the following observations made during his \(\alpha\) -particle scattering experiments? (a) Most \(\alpha\) particles were not appreciably deflected as they passed through the gold foil. (b) A few \(\alpha\) particles were deflected at very large angles. (c) What differences would you expect if beryllium foil were used instead of gold foil in the \(\alpha\) -particle scattering experiment?

Suppose a scientist repeats the Millikan oil-drop experiment, but reports the charges on the drops using an unusual (and imaginary) unit called the warmomb (wa). He obtains the following data for four of the drops: $$ \begin{array}{cc} \hline \text { Droplet } & \text { Calculated Charge (wa) } \\ \hline \mathrm{A} & 3.84 \times 10^{-8} \\ \mathrm{~B} & 4.80 \times 10^{-8} \\ \mathrm{C} & 2.88 \times 10^{-8} \\ \mathrm{D} & 8.64 \times 10^{-8} \end{array} $$ (a) If all the droplets were the same size, which would fall most slowly through the apparatus? (b) From these data, what is the best choice for the charge of the electron in warmombs? (c) Based on your answer to part (b), how many electrons are there on each of the droplets? (d) What is the conversion factor between warmombs and coulombs?

The natural abundance of \({ }^{3} \mathrm{He}\) is \(0.000137 \%\). (a) How many protons, neutrons, and electrons are in an atom of \({ }^{3} \mathrm{He}\) ? (b) Based on the sum of the masses of their subatomic particles, which is expected to be more massive, an atom of \({ }^{3} \mathrm{He}\) or an atom of \({ }^{3} \mathrm{H}\) (which is also called tritium)? (c) Based on your answer for part (b), what would need to be the precision of a mass spectrometer that is able to differentiate between peaks that are due to \({ }^{3} \mathrm{He}^{+}\) and \({ }^{3} \mathrm{H}^{+} ?\)

An \(\alpha\) particle is the nucleus of an \({ }^{4} \mathrm{He}\) atom. (a) How many protons and neutrons are in an \(\alpha\) particle? (b) What force holds the protons and neutrons together in the \(\alpha\) particle? (c) What is the charge on an \(\alpha\) particle in units of electronic charge? (d) The charge- to-mass ratio of an \(\alpha\) particle is \(4.8224 \times 10^{4} \mathrm{C} / \mathrm{g}\). Based on the charge on the particle, calculate its mass in grams and in amu. (e) By using the data in Table 2.1, compare your answer for part (d) with the sum of the masses of the individual subatomic particles. Can you explain the difference in mass? (If not, we will discuss such mass differences further in Chapter 21.)

A cube of gold that is \(1.00 \mathrm{~cm}\) on a side has a mass of \(19.3\) g. A single gold atom has a mass of \(197.0\) amu. (a) How many gold atoms are in the cube? (b) From the information given, estimate the diameter in \(\AA\) of a single gold atom. (c) What assumptions did you make in arriving at your answer for part (b)?

The diameter of a rubidium atom is \(4.95 \AA\). We will consider two different ways of placing the atoms on a surface. In arrangement \(\mathrm{A}\), all the atoms are lined up with one another. Arrangement \(\mathrm{B}\) is called a close-packed arrangement because the atoms sit in the "depressions" formed by the previous row of atoms: (a) Using arrangement A, how many Rb atoms could be placed on a square surface that is \(1.0 \mathrm{~cm}\) on a side? (b) How many Rb atoms could be placed on a square surface that is \(1.0 \mathrm{~cm}\) on a side, using arrangement \(\mathrm{B}\) ? (c) By what factor has the number of atoms on the surface increased in going to arrangement B from arrangement A? If extended to three dimensions, which arrangement would lead to a greater density for \(\mathrm{Rb}\) metal?

Identify the element represented by each of the following symbols and give the number of protons and neutrons in each: (a) \({ }_{33}^{74} \mathrm{X},(\mathrm{b}){ }_{53}^{127} \mathrm{X},(\mathrm{c})_{63}^{152} \mathrm{X},(\mathrm{d})_{83}^{209} \mathrm{X}\)

The element oxygen has three naturally occurring isotopes, with 8,9, and 10 neutrons in the nucleus, respectively. (a) Write the full chemical symbols for these three isotopes. (b) Describe the similarities and differences between the three kinds of atoms of oxygen.

Use Coulomb's law, \(F=k Q_{1} Q_{2} / d^{2}\), to calculate the electric force on an electron \(\left(Q=-1.6 \times 10^{-19} \mathrm{C}\right)\) exerted by a single proton if the particles are \(0.53 \times 10^{-10} \mathrm{~m}\) apart. The constant \(k\) in Coulomb's law is \(9.0 \times 10^{9} \mathrm{~N} \cdot \mathrm{m}^{2} / \mathrm{C}^{2}\). (The unit abbreviated \(\mathrm{N}\) is the Newton, the SI unit of force.)

The element lead (Pb) consists of four naturally occurring isotopes with atomic masses \(203.97302,205.97444\), \(206.97587\), and \(207.97663\) amu. The relative abundances of these four isotopes are \(1.4,24.1,22.1\), and \(52.4 \%\), respectively. From these data, calculate the atomic weight of lead.

Gallium (Ga) consists of two naturally occurring isotopes with masses of \(68.926\) and \(70.925\) amu. (a) How many protons and neutrons are in the nucleus of each isotope? Write the complete atomic symbol for each, showing the atomic number and mass number. (b) The average atomic mass of Ga is \(69.72\) amu. Calculate the abundance of each isotope.

Using a suitable reference such as the CRC Handbook of Chemistry and Physics or http://www.webelements.com, look up the following information for nickel: (a) the number of known isotopes, (b) the atomic masses (in amu) and the natural abundance of the five most abundant isotopes.

From the following list of elements \(-\mathrm{Ar}, \mathrm{H}, \mathrm{Ga}, \mathrm{Al}, \mathrm{Ca}\), \(\mathrm{Br}, \mathrm{Ge}, \mathrm{K}, \mathrm{O}-\) pick the one that best fits each description. Use each element only once: (a) an alkali metal, (b) an alkaline earth metal, (c) a noble gas, (d) a halogen, (e) a metalloid, (f) a nonmetal listed in group \(1 \mathrm{~A},(\mathrm{~g})\) a metal that forms a \(3+\) ion, \((h)\) a nonmetal that forms a \(2-\) ion, (i) an element that resembles aluminum.

The first atoms of seaborgium (Sg) were identified in 1974 . The longest-lived isotope of \(S g\) has a mass number of 266. (a) How many protons, electrons, and neutrons are in an \({ }^{266} \mathrm{Sg}\) atom? (b) Atoms of \(\mathrm{Sg}\) are very unstable, and it is therefore difficult to study this element's properties. Based on the position of \(S g\) in the periodic table, what element should it most closely resemble in its chemical properties?

Name each of the following oxides. Assuming that the compounds are ionic, what charge is associated with the metallic element in each case? (a) \(\mathrm{NiO}\), (b) \(\mathrm{MnO}_{2}\), (c) \(\mathrm{Cr}_{2} \mathrm{O}_{3}\), (d) \(\mathrm{MoO}_{3}\).

Iodic acid has the molecular formula \(\mathrm{HIO}_{3}\). Write the formulas for the following: (a) the iodate anion, (b) the periodate anion, (c) the hypoiodite anion, (d) hypoiodous acid, \((\mathrm{e})\) periodic acid.

Elements in the same group of the periodic table often form oxyanions with the same general formula. The anions are also named in a similar fashion. Based on these observations, suggest a chemical formula or name, as appropriate, for each of the following ions: (a) \(\mathrm{BrO}_{4}^{-}\), (b) \(\mathrm{SeO}_{3}^{2-},(\mathrm{c})\) arsenate ion, (d) hydrogen tellurate ion.

Carbonic acid occurs in carbonated beverages. When allowed to react with lithium hydroxide it produces lithium carbonate. Lithium carbonate is used to treat depression and bipolar disorder. Write chemical formulas for carbonic acid, lithium hydroxide, and lithium carbonate.

Give the chemical names of each of the following familiar compounds: (a) \(\mathrm{NaCl}\) (table salt), (b) \(\mathrm{NaHCO}_{3}\) (baking soda), (c) \(\mathrm{NaOCl}\) (in many bleaches), (d) \(\mathrm{NaOH}\) (caustic soda), (e) (NH \(_{4}\) ) \(_{2} \mathrm{CO}_{3}\) (smelling salts), (f) \(\mathrm{CaSO}_{4}\) (plaster of Paris).

Many familiar substances have common, unsystematic names. For each of the following, give the correct systematic name: (a) saltpeter, \(\mathrm{KNO}_{3} ;\) (b) soda ash, \(\mathrm{Na}_{2} \mathrm{CO}_{3} ;\) (c) lime, \(\mathrm{CaO}\); (d) muriatic acid, \(\mathrm{HCl}\); (e) Epsom salts, \(\mathrm{MgSO}_{4}\); (f) milk of magnesia, \(\mathrm{Mg}(\mathrm{OH})_{2}\).

Many ions and compounds have very similar names, and there is great potential for confusing them. Write the correct chemical formulas to distinguish between (a) calcium sulfide and calcium hydrogen sulfide, (b) hydrobromic acid and bromic acid, (c) aluminum nitride and aluminum nitrite, (d) iron(Il) oxide and iron(III) oxide, (e) ammonia and ammonium ion, (f) potassium sulfite and potassium bisulfite, \((g)\) mercurous chloride and mercuric chloride, \((\mathrm{h})\) chloric acid and perchloric acid.

The compound cyclohexane is an alkane in which six carbon atoms form a ring. The partial structural formula of the compound is as follows: (a) Complete the structural formula for cyclohexane. (b) Is the molecular formula for cyclohexane the same as that for \(n\) -hexane, in which the carbon atoms are in a straight line? If possible, comment on the source of any differences. (c) Propose a structural formula for cyclohexanol, the alcohol derived from cycIohexane.

The periodic table helps organize the chemical behaviors of the elements. As a class discussion or as a short essay, describe how the table is organized, and mention as many ways as you can think of in which the position of an element in the table relates to the chemical and physical properties of the element.