Chemistry

Julia Burdge

Chapter 2

Atoms, Molecules, and Ions - all with Video Answers

Educators

Chapter Questions

Problem 1

What are the hypotheses on which Dalton's atomic theory is based?

Charles Thomas

Charles Thomas

Numerade Educator

Problem 2

State the laws of definite proportions and multiple proportions. Illustrate each with an example.

Charles Thomas

Numerade Educator

Problem 3

Define the following terms: (a) $\alpha$ particle, (b) $\beta$ particle, (c) $\gamma$ ray, (d) X ray.

Charles Thomas

Numerade Educator

Problem 4

Name the types of radiation known to be emitted by radioactive elements.

Wan Deng

Numerade Educator

Problem 5

Compare the properties of the following: $\alpha$ particles, cathode rays, protons, neutrons, and electrons.

Charles Thomas

Numerade Educator

Problem 6

Describe the contributions of the following scientists to our knowledge of atomic structure: J. J. Thomson, R. A. Millikan, Ernest Rutherford, and James Chadwick.

Charles Thomas

Numerade Educator

Problem 7

Describe the experimental basis for believing that the nucleus occupies a very small fraction of the volume of the atom.

Wan Deng

Numerade Educator

Problem 8

The diameter of a neutral helium atom is about $1 \times 10^{2} \mathrm{pm}$ Suppose that we could line up helium atoms side by side in contact with one another. Approximately how many atoms would it take to make the distance $1 \mathrm{cm}$ from end to end?

Charles Thomas

Numerade Educator

Problem 9

Roughly speaking, the radius of an atom is about 10,000 times greater than that of its nucleus. If an atom were magnified so that the radius of its nucleus became $2.0 \mathrm{cm},$ about the size of a marble, what would be the radius of the atom in miles? $(1 \mathrm{mi}=1609 \mathrm{m} .)$

Wan Deng

Numerade Educator

Problem 10

Use the helium- 4 isotope to define atomic number and mass number. Why does knowledge of the atomic number enable us to deduce the number of electrons present in an atom?

Charles Thomas

Numerade Educator

Problem 11

Why do all atoms of an element have the same atomic number, although they may have different mass numbers?

Wan Deng

Numerade Educator

Problem 12

What do we call atoms of the same elements with different mass numbers?

Charles Thomas

Numerade Educator

Problem 13

Explain the meaning of each term in the symbol $_{Z}^{A} X$.

Wan Deng

Numerade Educator

Problem 14

What is the mass number of an iron atom that has 28 neutrons?

Charles Thomas

Numerade Educator

Problem 15

Calculate the number of neutrons of $^{239} \mathrm{Pu}$.

Wan Deng

Numerade Educator

Problem 16

For each of the following species, determine the number of protons and the number of neutrons in the nucleus: $_{2}^{3} \mathrm{He},_{2}^{4} \mathrm{He}$ $_{12}^{24} \mathrm{Mg},_{12}^{25} \mathrm{Mg},_{22}^{48} \mathrm{Ti},_{35}^{79} \mathrm{Br},_{78}^{195} \mathrm{Pt}$.

Charles Thomas

Numerade Educator

Problem 17

Indicate the number of protons, neutrons, and electrons in each of the following species: $_{7}^{15} \mathrm{N},_{16}^{33} \mathrm{S},_{29}^{63} \mathrm{Cu},_{38}^{84} \mathrm{Sr},_{56}^{130} \mathrm{Ba},_{74}^{186} \mathrm{W},_{80}^{202} \mathrm{Hg}$

Wan Deng

Numerade Educator

Problem 18

Write the appropriate symbol for each of the following isotopes: (a) $Z=11, A=23 ;$ (b) $Z=28, A=64,$ (c) $Z=50, A=115$ (d) $Z=20, A=42$.

Charles Thomas

Numerade Educator

Problem 19

Write the appropriate symbol for each of the following isotopes: (a) $Z=74, A=186 ;$ (b) $Z=80, A=201,$ (c) $Z=34, A=76$ (d) $Z=94, A=239$.

Charles Thomas

Numerade Educator

Problem 20

Determine the mass number of (a) a boron atom with 5 neutrons, (b) a magnesium atom with 14 neutrons, (c) a bromine atom with 46 neutrons, and (d) a mercury atom with 116 neutrons.

Charles Thomas

Numerade Educator

Problem 21

Determine the mass number of (a) a fluorine atom with 10 neutrons, (b) a sulfur atom with 18 neutrons, (c) an arsenic atom with 42 neutrons, and (d) a platinum atom with 114 neutrons.

Charles Thomas

Numerade Educator

Problem 22

The following radioactive isotopes are used in medicine for imaging organs, studying blood circulation, treating cancer, and so on. Give the number of neutrons present in each isotope: $^{198} \mathrm{Au},^{47} \mathrm{Ca},^{60} \mathrm{Co},^{18} \mathrm{F},^{125} \mathrm{I},^{131} \mathrm{I},^{42} \mathrm{K},^{43} \mathrm{K},^{24} \mathrm{Na},^{32} \mathrm{P},^{85} \mathrm{Sr},^{99} \mathrm{Tc}$.

Charles Thomas

Numerade Educator

Problem 23

What is the periodic table, and what is its significance in the study of chemistry?

Charles Thomas

Numerade Educator

Problem 24

State two differences between a metal and a nonmetal.

Wan Deng

Numerade Educator

Problem 25

Write the names and symbols for four elements in each of the following categories: (a) nonmetal, (b) metal, (c) metalloid.

Charles Thomas

Numerade Educator

Problem 26

Give two examples of each of the following: (a) alkali metals, (b) alkaline earth metals, (c) halogens, (d) noble gases, (e) chalcogens, (f) transition metals.

Charles Thomas

Numerade Educator

Problem 27

The explosion of an atomic bomb in the atmosphere releases many radioactive isotopes into the environment. One of the isotopes is $^{90} \mathrm{Sr}$. Via a relatively short food chain, it can enter the human body. Considering the position of strontium in the periodic table, explain why it is particularly harmful to humans.

Charles Thomas

Numerade Educator

Problem 28

Elements whose names end with -ium are usually metals; sodium is one example. Identify a nonmetal whose name also ends with -ium.

Charles Thomas

Numerade Educator

Problem 29

Describe the changes in properties (from metals to nonmetals or from nonmetals to metals) as we move (a) down a periodic group and (b) across the periodic table from left to right.

Wan Deng

Numerade Educator

Problem 30

Consult a handbook of chemical and physical data (ask your instructor where you can locate a copy of the handbook) to find (a) two metals less dense than water, (b) two metals more dense than mercury, (c) the densest known solid metallic element, and (d) the densest known solid nonmetallic element.

Charles Thomas

Numerade Educator

Problem 31

Group the following elements in pairs that you would expect to show similar chemical properties: $\mathrm{K}, \mathrm{F}, \mathrm{P}, \mathrm{Na}, \mathrm{Cl},$ and $\mathrm{N}$.

Wan Deng

Numerade Educator

Problem 32

Group the following elements in pairs that you would expect to show similar chemical properties: I, Ba, O, Br, S, and Ca.

Charles Thomas

Numerade Educator

Problem 33

Write the symbol for each of the following biologically important elements in the given periodic table: iron (present in hemoglobin for transporting oxygen), iodine (present in the thyroid gland), sodium (present in intracellular and extracellular fluids), phosphorus (present in bones and teeth), sulfur (present in proteins), and magnesium (present in chlorophyll molecules).

Charles Thomas

Numerade Educator

Problem 34

What is an atomic mass unit? Why is it necessary to introduce such a unit?

Dylan Miller

Numerade Educator

Problem 35

What is the mass (in amu) of a carbon- 12 atom? Why is the atomic mass of carbon listed as 12.01 amu in the table on the inside front cover of this book?

Benjamin Knudsen

Benjamin Knudsen

Numerade Educator

Problem 36

Explain clearly what is meant by the statement "The atomic mass of gold is 197.0 amu."

Dylan Miller

Numerade Educator

Problem 37

What information would you need to calculate the average atomic mass of an element?

Benjamin Knudsen

Benjamin Knudsen

Numerade Educator

Problem 38

The atomic masses of $_{17}^{35} \mathrm{Cl}(75.53 \text { percent })$ and $_{17}^{37} \mathrm{Cl}(24.47$ percent) are 34.968 and 36.956 amu, respectively. Calculate the average atomic mass of chlorine. The percentages in parentheses denote the relative abundances.

Charles Thomas

Numerade Educator

Problem 39

The atomic masses of $^{204} \mathrm{Pb}\left(1.4 \text { percent) },^{206} \mathrm{Pb}(24.1\right.$ percent), $^{207} \mathrm{Pb}(22.1 \text { percent }),$ and $^{208} \mathrm{Pb}(52.4 \text { percent })$ are $203.973020,205.974440,206.975872,$ and 207.976627 amu, respectively. Calculate the average atomic mass of lead. The percentages in parentheses denote the relative abundances.

Charles Thomas

Numerade Educator

Problem 40

The atomic masses of $^{203} \mathrm{Tl}$ and $^{205} \mathrm{Tl}$ are 202.972320 and 204.974401 amu, respectively. Calculate the natural abundances of these two isotopes. The average atomic mass of thallium is 204.4 amu.

Charles Thomas

Numerade Educator

Problem 41

The atomic masses of $^{6} \mathrm{Li}$ and $^{7} \mathrm{Li}$ are $6.0151 \mathrm{amu}$ and 7.0160 amu, respectively. Calculate the natural abundances of these two isotopes. The average atomic mass of $\mathrm{L i}$ is 6.941 amu.

Nicole Basile

Numerade Educator

Problem 42

What is the mass in grams of 13.2 amu?

Dylan Miller

Numerade Educator

Problem 43

How many atomic mass units are there in $8.4 \mathrm{g} ?$

Charles Thomas

Numerade Educator

Problem 44

What is the difference between an atom and a molecule?

Charles Thomas

Numerade Educator

Problem 45

What are allotropes? Give an example. How are allotropes different from isotopes?

Wan Deng

Numerade Educator

Problem 46

Describe the two commonly used molecular models.

Vishal Sharma

Numerade Educator

Problem 47

What does a chemical formula represent? Determine the ratio of the atoms in the following molecular formulas: (a) $\mathrm{NO},$ (b) $\mathrm{NCl}_{3}$ (c) $\mathrm{N}_{2} \mathrm{O}_{4},(\mathrm{d}) \mathrm{P}_{4} .\mathrm{O}_{6}$

Charles Thomas

Numerade Educator

Problem 48

Define molecular formula and empirical formula. What are the similarities and differences between the empirical formula and molecular formula of a compound?

Charles Thomas

Numerade Educator

Problem 49

Give an example of a case in which two molecules have different molecular formulas but the same empirical formula.

Charles Thomas

Numerade Educator

Problem 50

What is the difference between inorganic compounds and organic compounds?

Charles Thomas

Numerade Educator

Problem 51

Give one example each for a binary compound and a ternary compound. (A ternary compound is one that contains three different elements.)

Charles Thomas

Numerade Educator

Problem 52

Explain why the formula HCl can represent two different chemical systems.

Charles Thomas

Numerade Educator

Problem 53

For each of the following diagrams, determine whether it represents diatomic molecules, polyatomic molecules, molecules that are not compounds, molecules that are compounds, or an elemental form of the substance.

Charles Thomas

Numerade Educator

Problem 54

For each of the following diagrams, determine whether it represents diatomic molecules, polyatomic molecules, molecules that are not compounds, molecules that are compounds, or an elemental form of the substance.

Charles Thomas

Numerade Educator

Problem 55

Identify the following as elements or compounds: $\mathrm{NH}_{3}, \mathrm{N}_{2}, \mathrm{S}_{8}$ $\mathrm{NO}, \mathrm{CO}, \mathrm{CO}_{2}, \mathrm{H}_{2}, \mathrm{SO}_{2}$.

Charles Thomas

Numerade Educator

Problem 56

Give two examples of each of the following: (a) a diatomic molecule containing atoms of the same element, (b) a diatomic molecule containing atoms of different elements, (c) a polyatomic molecule containing atoms of the same element, (d) a polyatomic molecule containing atoms of different elements.

Wan Deng

Numerade Educator

Problem 57

Write the empirical formulas of the following compounds: (a) $\mathrm{C}_{2} \mathrm{N}_{2},$ (b) $\mathrm{C}_{6} \mathrm{H}_{6},$ (c) $\mathrm{C}_{9} \mathrm{H}_{20},$ (d) $\mathrm{P}_{4} \mathrm{O}_{10},$ (e) $\mathrm{B}_{2} \mathrm{H}_{6}$.

Charles Thomas

Numerade Educator

Problem 58

Write the empirical formulas of the following compounds: (a) $\mathrm{Al}_{2} \mathrm{Br}_{6},$ (b) $\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{4},(\mathrm{c}) \mathrm{N}_{2} \mathrm{O}_{5},(\mathrm{d}) \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$.

Charles Thomas

Numerade Educator

Problem 59

Write the molecular formula of alanine, an amino acid used in protein synthesis. The color codes are black (carbon), blue (nitrogen), red (oxygen), and white (hydrogen).

Charles Thomas

Numerade Educator

Problem 60

Write the molecular formula of ethanol. The color codes are: black (carbon), red (oxygen), and white (hydrogen).

Charles Thomas

Numerade Educator

Problem 61

Name the following binary molecular compounds: (a) $\mathrm{NCl}_{3}$ (b) $\mathrm{IF}_{7},$ (c) $\mathrm{P}_{4} \mathrm{O}_{6},$ (d) $\mathrm{S}_{2} \mathrm{Cl}_{2}$.

Charles Thomas

Numerade Educator

Problem 62

Write chemical formulas for the following molecular compounds: (a) phosphorus tribromide, (b) dinitrogen tetrafluoride, (c) xenon tetroxide, (d) selenium trioxide.

Charles Thomas

Numerade Educator

Problem 63

Write the molecular formulas and names of the following compounds.

Wan Deng

Numerade Educator

Problem 64

Write the molecular formulas and names of the following compounds.

Wan Deng

Numerade Educator

Problem 65

Give an example of each of the following: (a) a monatomic cation, (b) a monatomic anion, (c) a polyatomic cation, (d) a polyatomic anion.

Wan Deng

Numerade Educator

Problem 66

What is an ionic compound? How is electrical neutrality maintained in an ionic compound?

Charles Thomas

Numerade Educator

Problem 67

Explain why the chemical formulas of ionic compounds are usually the same as their empirical formulas.

Wan Deng

Numerade Educator

Problem 68

What is the Stock system? What are its advantages over the older system of naming cations?

Wan Deng

Numerade Educator

Problem 69

Give the number of protons and electrons in each of the following common ions: $\mathrm{Na}^{+}, \mathrm{Ca}^{2+}, \mathrm{Al}^{3+}, \mathrm{Fe}^{2+}, \mathrm{I}^{-}, \mathrm{F}^{-}, \mathrm{S}^{2-}, \mathrm{O}^{2-}, \mathrm{N}^{3-}$

Charles Thomas

Numerade Educator

Problem 70

Give the number of protons and electrons in each of the following common ions: $\mathrm{K}^{+}, \mathrm{Mg}^{2+}, \mathrm{Fe}^{3+}, \mathrm{Br}^{-}, \mathrm{Mn}^{2+}, \mathrm{C}^{4-}, \mathrm{Cu}^{2+}$

Wan Deng

Numerade Educator

Problem 71

Write the formulas for the following ionic compounds:
(a) sodium oxide, (b) iron sulfide (containing the $\mathrm{Fe}^{2+}$ ion),
(c) cobalt sulfate (containing the $\mathrm{Co}^{3+}$ and $\mathrm{SO}_{4}^{2-}$ ions),
(d) barium fluoride.

Charles Thomas

Numerade Educator

Problem 72

Write the formulas for the following ionic compounds: (a) copper bromide (containing the $\mathrm{Cu}^{+}$ ion), (b) manganese oxide (containing the $\mathrm{Mn}^{3+}$ ion), (c) mercury iodide (containing the $\mathrm{Hg}_{2}^{2+}$ ion), (d) magnesium phosphate (containing the $\mathrm{PO}_{4}^{3-}$ ion).

Charles Thomas

Numerade Educator

Problem 73

Which of the following compounds are likely to be ionic? Which are likely to be molecular? $\mathrm{SiCl}_{4}, \mathrm{LiF}, \mathrm{BaCl}_{2}, \mathrm{B}_{2} \mathrm{H}_{6}, \mathrm{KCl}, \mathrm{C}_{2} \mathrm{H}_{4}$

Charles Thomas

Numerade Educator

Problem 74

Which of the following compounds are likely to be ionic? Which are likely to be molecular? $\mathrm{CH}_{4}, \mathrm{NaBr}, \mathrm{BaF}_{2}, \mathrm{CCl}_{4}, \mathrm{ICl}, \mathrm{CsCl}$ $\mathrm{NF}_{3}$.

Charles Thomas

Numerade Educator

Problem 75

Name the following compounds: (a) $\mathrm{KH}_{2} \mathrm{PO}_{4},$ (b) $\mathrm{K}_{2} \mathrm{HPO}_{4},$ (c) HBr (gas), (d) HBr (in water), (e) $\mathrm{Li}_{2} \mathrm{CO}_{3},(\mathrm{f}) \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7},$ (g) $\mathrm{NH}_{4} \mathrm{NO}_{2},$ (h) $\mathrm{HIO}_{3},$ (i) $\mathrm{PF}_{5},$ (j) $\mathrm{P}_{4} \mathrm{O}_{6},$ (k) $\mathrm{CdI}_{2},$ (l) $\mathrm{SrSO}_{4}$ $(\mathrm{m}) \mathrm{Al}(\mathrm{OH})_{3}$.

Charles Thomas

Numerade Educator

Problem 76

Name the following compounds: (a) $\mathrm{KClO},$ (b) $\mathrm{Ag}_{2} \mathrm{CO}_{3}$ (c) $\mathrm{HNO}_{2},$ (d) $\mathrm{KMnO}_{4},$ (e) $\mathrm{CsClO}_{3},$ (f) $\mathrm{KNH}_{4} \mathrm{SO}_{4},$ (g) $\mathrm{FeO}$, (h) $\mathrm{Fe}_{2} \mathrm{O}_{3},$ (i) $\mathrm{TiCl}_{4},$ (j) $\mathrm{NaH},(\mathrm{k}) \mathrm{Li}_{3} \mathrm{N},(\mathrm{l}) \mathrm{Na}_{2} \mathrm{O},(\mathrm{m}) \mathrm{Na}_{2} \mathrm{O}_{2}$.

Charles Thomas

Numerade Educator

Problem 77

Write the formulas for the following compounds: (a) rubidium nitrite, (b) potassium sulfide, (c) sodium hydrogen sulfide,
(d) magnesium phosphate, (e) calcium hydrogen phosphate, (f) potassium dihydrogen phosphate, (g) iodine heptafluoride, (h) ammonium sulfate, (i) silver perchlorate, (j) boron trichloride.

Charles Thomas

Numerade Educator

Problem 78

Write the formulas for the following compounds: (a) copper(I) cyanide, (b) strontium chlorite, (c) perbromic acid, (d) hydroiodic acid, (e) disodium ammonium phosphate, (f) lead(II) carbonate, (g) tin(II) fluoride, (h) tetraphosphorus decasulfide, (i) mercury(II) oxide, (j) mercury(I) iodide, (k) selenium hexafluoride.

Wan Deng

Numerade Educator

Problem 79

In the diagrams shown here, match each of the drawings with the following ionic compounds: $\mathrm{Al}_{2} \mathrm{O}_{3}, \mathrm{LiH}, \mathrm{Na}_{2} \mathrm{S}, \mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}$
(Green spheres represent cations and red spheres represent anions.)

Charles Thomas

Numerade Educator

Problem 80

Given the formulas for the ionic compounds, draw the correct ratio of cations to anions as shown in Problem 2.79: (a) $\mathrm{BaSO}_{4}$ (b) $\mathrm{CaF}_{2},$ (c) $\mathrm{Mg}_{3} \mathrm{N}_{2},$ (d) $\mathrm{K}_{2} \mathrm{O}$.

Charles Thomas

Numerade Educator

Problem 81

Define the following terms: acids, bases, oxoacids, oxoanions, and hydrates.

Wan Deng

Numerade Educator

Problem 82

A sample of a uranium compound is found to be losing mass gradually. Explain what is happening to the sample.

Charles Thomas

Numerade Educator

Problem 83

In which one of the following pairs do the two species resemble each other most closely in chemical properties: (a) $_{1}^{1} \mathrm{H}$ and $_{1}^{1} \mathrm{H}^{+},$ (b) $_{7}^{14} \mathrm{N}$ and $_{7}^{14} \mathrm{N}^{3-},(\mathrm{c})_{6}^{12} \mathrm{C}$ and $_{6}^{13} \mathrm{C} ?$ Explain.

Charles Thomas

Numerade Educator

Problem 84

One isotope of a metallic element has mass number 65 and 35 neutrons in the nucleus. The cation derived from the isotope has 28 electrons. Write the symbol for this cation.

Charles Thomas

Numerade Educator

Problem 85

One isotope of a nonmetallic element has mass number 127 and 74 neutrons in the nucleus. The anion derived from the isotope has 54 electrons. Write the symbol for this anion.

Pronoy Sinha

Numerade Educator

Problem 86

The following table gives numbers of electrons, protons, and neutrons in atoms or ions of a number of elements. Answer the following: (a) Which of the species are neutral? (b) Which are negatively charged? (c) Which are positively charged? (d) What are the conventional symbols for all the species?

Charles Thomas

Numerade Educator

Problem 87

What is wrong with or ambiguous about the phrase "four molecules of NaCl"?

Wan Deng

Numerade Educator

Problem 88

The following phosphorus sulfides are known: $\mathrm{P}_{4} \mathrm{S}_{3}, \mathrm{P}_{4} \mathrm{S}_{7},$ and $\mathrm{P}_{4} \mathrm{S}_{10} .$ Do these compounds obey the law of multiple proportions?

Charles Thomas

Numerade Educator

Problem 89

Which of the following are elements, which are molecules but not compounds, which are compounds but not molecules, and which are both compounds and molecules? (a) $\mathrm{SO}_{2},$ (b) $\mathrm{S}_{8},$ (c) $\mathrm{Cs},$ (d) $\mathrm{N}_{2} \mathrm{O}_{5},$ (e) $\mathrm{O},$ (f) $\mathrm{O}_{2},(\mathrm{g}) \mathrm{O}_{3},$ (h) $\mathrm{CH}_{4},$ (i) $\mathrm{KBr},(\mathrm{j}) \mathrm{S},$ (k) $\mathrm{P}_{4},$ (l) $\mathrm{LiF}$.

Charles Thomas

Numerade Educator

Problem 90

What is wrong with the name (given in parentheses or brackets) for each of the following compounds: (a) $\mathrm{BaCl}_{2}$ (barium dichloride), (b) $\mathrm{Fe}_{2} \mathrm{O}_{3}[\text { iron }(\mathrm{II}) \text { oxide }],(\mathrm{c}) \mathrm{CsNO}_{2}($ cesium nitrate), (d) $\mathrm{Mg}\left(\mathrm{HCO}_{3}\right)_{2}$ [magnesium(II) bicarbonate]?

Charles Thomas

Numerade Educator

Problem 91

Discuss the significance of assigning an atomic mass of exactly 12 amu to the carbon-12 isotope.

Charles Thomas

Numerade Educator

Problem 92

Determine what is wrong with the chemical formula and write the correct chemical formula for each of the following compounds: (a) ( $\mathrm{NH}_{3}$ ) $_{2} \mathrm{CO}_{3}$ (ammonium carbonate), (b) $\mathrm{CaOH}$ (calcium hydroxide), (c) $\mathrm{CdSO}_{3}$ (cadmium sulfide), (d) $\mathrm{ZnCrO}_{4}$ (zinc dichromate).

Charles Thomas

Numerade Educator

Problem 93

Fill in the blanks in the table:
$$\begin{array}{|l|c|c|c|c|c|}
\hline \text { Symbol } & & _{24}^{54} \mathrm{Fe}^{2+} & & & \\
\hline \text { Protons } & 5 & & & 79 & 86 \\
\hline \text { Neutrons } & 6 & & 16 & 117 & 136 \\
\hline \text { Electrons } & 5 & & 18 & 79 & \\
\hline \text { Net charge } & & & -3 & & 0 \\
\hline
\end{array}$$

Charles Thomas

Numerade Educator

Problem 94

(a) Which elements are most likely to form ionic compounds?
(b) Which metallic elements are most likely to form cations with different charges?

Wan Deng

Numerade Educator

Problem 95

Write the formula of the common ion derived from each of the following: (a) $\mathrm{Li}$, (b) $\mathrm{S}$, (c) $\mathrm{I}$, (d) $\mathrm{N},$ (e) $\mathrm{Al},$, (f) $\mathrm{Cs},$, (g) $\mathrm{Mg},$.

Charles Thomas

Numerade Educator

Problem 96

Which of the following symbols provides more information about the atom: $^{23} \mathrm{Na}$ or $_{11} \mathrm{Na} ?$ Explain.

Wan Deng

Numerade Educator

Problem 97

Write the chemical formulas and names of the binary acids and oxoacids that contain Group 7 A elements. Do the same for elements in Groups $3 \mathrm{A}, 4 \mathrm{A}, 5 \mathrm{A},$ and $6 \mathrm{A}$.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 98

Determine the molecular and empirical formulas of the compounds shown here. (Black spheres are carbon, and white spheres are hydrogen.)

Charles Thomas

Numerade Educator

Problem 99

For the noble gases (the Group 8 A elements) $_{2}^{4} \mathrm{He},_{10}^{20} \mathrm{Ne},_{18}^{40} \mathrm{Ar},$ $_{36}^{84} \mathrm{Kr},$ and $_{54}^{132} \mathrm{Xe},$(a) determine the number of protons and neutrons in the nucleus of each atom, and (b) determine the ratio of neutrons to protons in the nucleus of each atom. Describe any general trend you discover in the way this ratio changes with increasing atomic number.

Charles Thomas

Numerade Educator

Problem 100

List the elements that exist as gases at room temperature. (Hint: Most of these elements can be found in Groups $5 \mathrm{A}, 6 \mathrm{A}, 7 \mathrm{A}$ and 8A.)

Charles Thomas

Numerade Educator

Problem 101

The Group $1 \mathrm{B}$ metals, $\mathrm{Cu}, \mathrm{Ag},$ and $\mathrm{Au},$ are called coinage metals. What chemical properties make them especially suitable for making coins and jewelry?

Charles Thomas

Numerade Educator

Problem 102

The elements in Group 8 A of the periodic table are called noble gases. Can you suggest what "noble" means in this context?

Wan Deng

Numerade Educator

Problem 103

The formula for calcium oxide is $\mathrm{CaO}$. What are the formulas for magnesium oxide and strontium oxide?

Charles Thomas

Numerade Educator

Problem 104

A common mineral of barium is barytes, or barium sulfate $\left(\mathrm{BaSO}_{4}\right) .$ Because elements in the same periodic group have similar chemical properties, we might expect to find some radium sulfate ( $\mathrm{RaSO}_{4}$ ) mixed with barytes since radium is the last member of Group 2 A. However, the only source of radium compounds in nature is in uranium minerals. Why?

Charles Thomas

Numerade Educator

Problem 105

List five elements each that are (a) named after places, (b) named after people, (c) named after a color. (Consult http://www. Google.com, http://www.Wikipedia.com, or http://www. Webelements.com.)

Charles Thomas

Numerade Educator

Problem 106

Name the only country that is named after an element. (Hint: This country is in South America.)

Charles Thomas

Numerade Educator

Problem 107

Fluorine reacts with hydrogen (H) and deuterium (D) to form hydrogen fluoride (HF) and deuterium fluoride (DF), where deuterium $\left(_{1}^{2} \mathrm{H}\right)$ is an isotope of hydrogen. Would a given amount of fluorine react with different masses of the two hydrogen isotopes? Does this violate the law of definite proportion? Explain.

Charles Thomas

Numerade Educator

Problem 108

Predict the formula and name of a binary compound formed from the following elements: (a) $\mathrm{Na}$ and $\mathrm{H},$ (b) $\mathrm{B}$ and $\mathrm{O},$ (c) $\mathrm{Na}$ and $\mathrm{S}$ (d) Al and $\mathrm{F},$ (e) $\mathrm{F}$ and $\mathrm{O},$ (f) $\mathrm{Sr}$ and $\mathrm{Cl}$

Wan Deng

Numerade Educator

Problem 109

Identify each of the following elements: (a) a halogen whose anion contains 36 electrons, (b) a radioactive noble gas with 86 protons, (c) a Group 6 A element whose anion contains 36 electrons, (d) an alkali metal cation that contains 36 electrons, (e) a Group 4A cation that contains 80 electrons.

Charles Thomas

Numerade Educator

Problem 110

Show the locations of (a) alkali metals, (b) alkaline earth metals, (c) the halogens, and (d) the noble gases in the given outline of a periodic table. Also draw dividing lines between metals and metalloids and between metalloids and nonmetals.

Charles Thomas

Numerade Educator

Problem 111

Fill in the blanks in the table.

Charles Thomas

Numerade Educator

Problem 112

Some compounds are better known by their common names than by their systematic chemical names. Give the chemical formulas of the following substances: (a) Dry ice, (b) salt, (c) laughing gas, (d) marble (chalk, limestone), (e) baking soda, (f) ammonia, (g) water, (h) milk of magnesia, (i) epsom salt.

Charles Thomas

Numerade Educator

Problem 113

On page 36 it was pointed out that mass and energy are alternate aspects of a single entity called mass-energy. The relationship between these two physical quantities is Einstein's equation, $E=m c^{2},$ where $E$ is energy, $m$ is mass, and $c$ is the speed of light. In a combustion experiment, it was found that $12.096 \mathrm{g}$ of hydrogen molecules combined with 96.000 g of oxygen molecules to form water and released $1.715 \times 10^{3} \mathrm{kJ}$ of heat. Use Einstein's equation to calculate the corresponding mass change in this process, and comment on whether or not the law of conservation of mass holds for ordinary chemical processes.

Charles Thomas

Numerade Educator

Problem 114

(a) Describe Rutherford's experiment and how the results revealed the nuclear structure of the atom. (b) Consider the "Na atom. Given that the radius and mass of the nucleus are $3.04 \times 10^{-15} \mathrm{m}$ and $3.82 \times 10^{-23} \mathrm{g},$ respectively, calculate the density of the nucleus in $\mathrm{g} / \mathrm{cm}^{3} .$ The radius of a $^{23} \mathrm{Na}$ atom is 186 pm. Calculate the density of the space occupied by the electrons outside the nucleus in the sodium atom. Do your results support Rutherford's model of an atom? [The volume of a sphere of radius $\left.r \text { is } \frac{4}{3} \pi r^{3} .\right]$

Charles Thomas

Numerade Educator

Problem 115

Draw all possible structural formulas of the following hydrocarbons: $\mathrm{CH}_{4}, \mathrm{C}_{2} \mathrm{H}_{6}, \mathrm{C}_{3} \mathrm{H}_{8}, \mathrm{C}_{4} \mathrm{H}_{10},$ and $\mathrm{C}_{5} \mathrm{H}_{12}$

Charles Thomas

Numerade Educator

Problem 116

Draw two different structural formulas based on the molecular formula $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}$. Is the fact that you can have more than one compound with the same molecular formula consistent with Dalton's atomic theory?

Charles Thomas

Numerade Educator

Problem 117

Ethane and acetylene are two gaseous hydrocarbons. Chemical analyses show that in one sample of ethane, $2.65 \mathrm{g}$ of carbon are combined with $0.665 \mathrm{g}$ of hydrogen, and in one sample of acetylene, $4.56 \mathrm{g}$ of carbon are combined with $0.383 \mathrm{g}$ of hydrogen. (a) Are these results consistent with the law of multiple proportions? (b) Write reasonable molecular formulas for these compounds.

Wan Deng

Numerade Educator

Problem 118

A cube made of platinum (Pt) has an edge length of $1.0 \mathrm{cm}$. (a) Calculate the number of $\mathrm{Pt}$ atoms in the cube. (b) Atoms are spherical in shape. Therefore, the Pt atoms in the cube cannot fill all the available space. If only 74 percent of the space inside the cube is taken up by Pt atoms, calculate the radius in picometers of a Pt atom. The density $\mathrm{Pt}$ is $21.45 \mathrm{g} / \mathrm{cm}^{3}$, and the mass of a single $P t$ atom is $3.240 \times 10^{-22} \mathrm{g}$. [The volume of a sphere of radius $\left.r \text { is } \frac{4}{3} \pi r^{3} .\right]$

Charles Thomas

Numerade Educator

Problem 119

A monatomic ion has a charge of $+2 .$ The nucleus of the parent atom has a mass number of $55 .$ If the number of neutrons in the nucleus is 1.2 times that of the number of protons, what is the name and symbol of the element?

Wan Deng

Numerade Educator

Problem 120

In the following $2 \times 2$ crossword, each letter must be correct in four ways: horizontally, vertically, diagonally, and by itself. When the puzzle is complete, the four spaces will contain the overlapping symbols of 10 elements. Use capital letters for each square. There is only one correct solution.
Horizontal
1-2: Two-letter symbol for a metal used in ancient times
3-4: Two-letter symbol for a metal that burns in air and is found in Group $5 \mathrm{A}$
Vertical
1-3: Two-letter symbol for a metalloid
2-4: Two-letter symbol for a metal used in U.S. coins
Single Square
1: A colorful nonmetal
2: A colorless gaseous nonmetal
3: An element that makes fireworks green
4: An element that has medicinal uses
Diagonal
1-4: Two-letter symbol for an element used in electronics
2-3: Two-letter symbol for a metal used with Zr to make wires for superconducting magnets

Charles Thomas

Numerade Educator

Problem 121

Name the given acids.

Charles Thomas

Numerade Educator