Chapter 2

What are the three fundamental particles from which atoms are built? What are their electric charges? Which of these particles constitute the nucleus of an atom? Which is the least massive particle of the three?

Define mass number. What is the difference between mass number and atomic mass?

A gold atom has a radius of \(145 \mathrm{pm}\). If you could string gold atoms like beads on a thread, how many atoms would you need to have a necklace \(36 \mathrm{cm}\) long?

Give the complete symbol \(\left(_{Z}^{A} \mathrm{X}\right),\) including atomic number and mass number, for each of the following atoms: (a) magnesium with 15 neutrons, (b) titanium with 26 neutrons, and (c) zinc with 32 neutrons.

Give the complete symbol \(\left(_{Z}^{A} X\right),\) including atomic number and mass number, of (a) a nickel atom with 31 neutrons, (b) a plutonium atom with 150 neutrons, and (c) a tungsten atom with 110 neutrons.

How many electrons, protons, and neutrons are there in each of the following atoms? (a) magnesium- \(24,^{24} \mathrm{Mg}\) (b) tin- \(119,^{119} \mathrm{Sn}\) (c) thorium-232, \(^{232} \mathrm{Th}\) (d) carbon- \(13,^{13} \mathrm{C}\) (e) copper-63, \(^{63} \mathrm{Cu}\) (f) bismuth- \(205,^{205} \mathrm{Bi}\)

Atomic structure. (a) The synthetic radioactive element technetium is used in many medical studies. Give the number of electrons, protons, and neutrons in an atom of technetium-99. (b) Radioactive americium-241 is used in household smoke detectors and in bone mineral analysis. Give the number of electrons, protons, and neutrons in an atom of americium-241.

The mass of an 16 O atom is 15.995 u. What is its mass relative to the mass of an atom of \(^{12} \mathrm{C} ?\)

Cobalt has three radioactive isotopes used in medical studies. Atoms of these isotopes have \(30,31,\) and 33 neutrons, respectively. Give the symbol for each of these isotopes.

Naturally occurring silver exists as two isotopes having mass numbers 107 and \(109 .\) How many protons, neutrons, and electrons are there in each of these isotopes?

Name and describe the composition of the three hydrogen isotopes.

Which of the following are isotopes of element X, the atomic number for which is \(_{9}^{19}\mathrm{g} \mathrm{X},_{9}^{20} \mathrm{g} \mathrm{X},_{18}^{9} \mathrm{X},\) and \(_{9}^{21}\mathrm{g} ?\)

Thallium has two stable isotopes, \(^{203} \mathrm{Tl}\) and \(^{205} \mathrm{Tl}\). Knowing that the atomic weight of thallium is 204.4 which isotope is the more abundant of the two?

Verify that the atomic weight of lithium is \(6.94,\) given the following information: \(^{6} \mathrm{Li},\) mass \(=6.015121 \mathrm{u} ;\) percent abundance \(=7.50 \%\) \(^{7} \mathrm{Li},\) mass \(=7.016003 \mathrm{u} ;\) percent abundance \(=92.50 \%\)

Verify that the atomic weight of magnesium is 24.31 given the following information: $$\begin{aligned} &^{24} \mathrm{Mg}, \text { mass }=23.985042 \mathrm{u} ; \text { percent abundance }=78.99 \%\\\ &^{25} \mathrm{Mg}, \text { mass }=24.985837 \mathrm{u} ; \text { percent abundance }=10.00 \%\\\ &^{26} \mathrm{Mg}, \text { mass }=25.982593 \text { u; percent abundance }=11.01 \% \end{aligned}$$

Silver (Ag) has two stable isotopes, \(107 \mathrm{Ag}\) and \(^{109} \mathrm{Ag}\). The isotopic mass of \(^{107} \mathrm{Ag}\) is \(106.9051,\) and the isotopic mass of \(^{109} \mathrm{Ag}\) is \(108.9047 .\) The atomic weight of Ag, from the periodic table, is \(107.868 .\) Estimate the percent of \(^{107} \mathrm{Ag}\) in a sample of the element. (a) \(0 \%\) (b) \(25 \%\) (c) \(50 \%\) (d) \(75 \%\)

Titanium and thallium have symbols that are easily confused with each other. Give the symbol, atomic number, atomic weight, and group and period number of each element. Are they metals, metalloids, or nonmetals?

In Groups \(4 \mathrm{A}-6 \mathrm{A},\) there are several elements whose symbols begin with S. Name these elements, and for each one give its symbol, atomic number, group number, and period. Describe each as a metal, metalloid, or nonmetal.

How many periods of the periodic table have 8 elements, how many have 18 elements, and how many have 32 elements?

How many elements occur in the seventh period? What is the name given to the majority of these elements, and what well-known property characterizes them?

Select answers to the questions listed below from the following list of elements whose symbols start with the letter C: \(\mathbf{C}, \mathbf{C a}, \mathbf{C r}, \mathbf{C o}, \mathbf{C d}, \mathbf{C l}, \mathbf{C s}, \mathbf{C e}, \mathbf{C m}, \mathbf{C u},\) and Cf. (You should expect to use some symbols more than once. \()\) (a) Which are nonmetals? (b) Which are main group elements? (c) Which are lanthanides? (d) Which are transition elements? (e) Which are actinides? (f) Which are gases?

Give the name and chemical symbol for the following. (a) a nonmetal in the second period (b) an alkali metal in the fifth period (c) the third-period halogen (d) an element that is a gas at \(20^{\circ} \mathrm{C}\) and 1 atmosphere pressure

Classify the following elements as metals, metalloids, or nonmetals: \(\mathrm{N}, \mathrm{Na}, \mathrm{Ni}, \mathrm{Ne},\) and \(\mathrm{Np}\)

Here are symbols for five of the seven elements whose names begin with the letter \(\mathrm{B}: \mathrm{B}, \mathrm{Ba}, \mathrm{Bk}, \mathrm{Bi},\) and \(\mathrm{Br}\) Match each symbol with one of the descriptions below. (a) a radioactive element (b) a liquid at room temperature (c) a metalloid (d) an alkaline earth element (e) a group 5 A element

What is the charge on the common monatomic ions of the following elements? (a) magnesium (b) zinc (c) nickel (d) gallium

What is the charge on the common monatomic ions of the following elements? (a) selenium (b) fluorine (c) iron (d) nitrogen

Give the symbol, including the correct charge, for each of the following ions: (a) barium ion (b) titanium(IV) ion (c) phosphate ion (d) hydrogen carbonate ion (e) sulfide ion (f) perchlorate ion (g) cobalt(II) ion (h) sulfate ion

Give the symbol, including the correct charge, for each of the following ions: (a) permanganate ion (b) nitrite ion (c) dihydrogen phosphate ion (d) ammonium ion (e) phosphate ion (f) sulfite ion

When a potassium atom becomes a monatomic ion, how many electrons does it lose or gain? What noble gas atom has the same number of electrons as a potassium ion?

When oxygen and sulfur atoms become monatomic ions, how many electrons does each lose or gain? Which noble gas atom has the same number of electrons as an oxide ion? Which noble gas atom has the same number of electrons as a sulfide ion?

What are the charges on the ions in an ionic compound containing the elements barium and bromine? Write the formula for the compound.

What are the charges of the ions in an ionic compound containing cobalt(III) and fluoride ions? Write the formula for the compound.

Give the formula and the number of each ion that makes up each of the following compounds: (a) \(\mathrm{K}_{2} \mathrm{S}\) (b) \(\cos \mathrm{O}_{4}\) (c) \(\mathrm{KMnO}_{4}\) (d) \(\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}\) (e) \(\mathrm{Ca}(\mathrm{ClO})_{2}\) (f) \(\mathrm{NaCH}_{3} \mathrm{CO}_{2}\)

Give the formula and the number of each ion that makes up each of the following compounds: (a) \(\mathrm{Mg}\left(\mathrm{CH}_{3} \mathrm{CO}_{2}\right)_{2}\) (b) \(\mathrm{Al}(\mathrm{OH})_{3}\) (c) \(\mathrm{CuCO}_{3}\) (d) \(\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}\) (e) \(\mathrm{Ca}(\mathrm{ClO})_{2}\) (f) \(\mathrm{NaCH}_{3} \mathrm{CO}_{2}\)

Cobalt forms \(\mathrm{Co}^{2+}\) and \(\mathrm{Co}^{3+}\) ions. Write the formulas for the two cobalt oxides formed by these transition metal ions.

Platinum is a transition element and forms \(\mathrm{Pt}^{2+}\) and \(\mathrm{Pt}^{4+}\) ions. Write the formulas for the compounds of each of these ions with (a) chloride ions and (b) sulfide ions.

Which of the following are correct formulas for ionic compounds? For those that are not, give the correct formula. (a) \(\mathrm{AlCl}_{2}\) (b) \(\mathrm{KF}_{2}\) (c) \(\mathrm{Ga}_{2} \mathrm{O}_{3}\) (d) MgS

Which of the following are correct formulas for ionic compounds? For those that are not, give the correct formula. (a) \(\mathrm{Ca}_{2} \mathrm{O}\) (b) \(\operatorname{SrBr}_{2}\) (c) \(\mathrm{Fe}_{2} \mathrm{O}_{5}\) (d) \(\mathrm{Li}_{2} \mathrm{O}\)

Name each of the following ionic compounds: (a) \(\mathrm{K}_{2} \mathrm{S}\) (b) \(\cos 0_{4}\) (c) \(\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}\) (d) \(\mathrm{Ca}(\mathrm{ClO})_{2}\)

Name each of the following ionic compounds: (a) \(\mathrm{Ca}\left(\mathrm{CH}_{3} \mathrm{CO}_{2}\right)_{2}\) (b) \(\mathrm{Ni}_{3}\left(\mathrm{PO}_{4}\right)_{2}\) (c) \(\mathrm{Al}(\mathrm{OH})_{3}\) (d) \(\mathrm{KH}_{2} \mathrm{PO}_{4}\)

Give the formula for each of the following ionic compounds: (a) ammonium carbonate (b) calcium iodide (c) copper(II) bromide (d) aluminum phosphate (e) silver( I) acetate

Give the formula for each of the following ionic compounds: (a) calcium hydrogen carbonate (b) potassium permanganate (c) magnesium perchlorate (d) potassium hydrogen phosphate (e) sodium sulfite

Write the formulas for the four ionic compounds that can be made by combining each of the cations \(\mathrm{Na}^{+}\) and Ba \(^{2+}\) with the anions \(\mathrm{CO}_{3}^{2-}\) and \(\mathrm{I}^{-}\). Name each of the compounds.

Write the formulas for the four ionic compounds that can be made by combining the cations \(\mathrm{Mg}^{2+}\) and \(\mathrm{Fe}^{3+}\) with the anions \(\mathrm{PO}_{4}^{3-}\) and \(\mathrm{NO}_{3}^{-} .\) Name each compound formed.

Sodium ions, Na \(^{+}\), form ionic compounds with fluoride ions, \(\mathrm{F}^{-},\) and iodide ions, \(\mathrm{I}^{-}\). The radii of these ions are as follows: \(\mathrm{Na}^{+}=116 \mathrm{pm} ; \mathrm{F}^{-}=119 \mathrm{pm} ;\) and \(\mathrm{I}^{-}=206 \mathrm{pm} .\) In which ionic compound, \(\mathrm{NaF}\) or \(\mathrm{NaI}\) are the forces of attraction between cation and anion stronger? Explain your answer.

Consider the two ionic compounds \(\mathrm{NaCl}\) and \(\mathrm{CaO} .\) In which compound are the cation-anion attractive forces stronger? Explain your answer.

Name each of the following binary, nonionic compounds: (a) \(\mathrm{NF}_{3}\) (b) HI (c) \(\mathrm{BI}_{3}\) (d) \(\mathrm{PF}_{5}\)

Name each of the following binary, nonionic compounds: (a) \(\mathrm{N}_{2} \mathrm{O}_{5}\) (b) \(\mathrm{P}_{4} \mathrm{S}_{3}\) (c) \(\mathrm{OF}_{2}\) (d) \(\mathrm{XeF}_{4}\)

Give the formula for each of the following compounds: (a) sulfur dichloride (b) dinitrogen pentaoxide (c) silicon tetrachloride (d) diboron trioxide (commonly called boric oxide)

Give the formula for each of the following compounds: (a) bromine trifluoride (b) xenon difluoride (c) hydrazine (d) diphosphorus tetrafluoride (e) butane