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2-21 Answer true or false. (a) A proton and an electron have the same mass but opposite charges. (b) The mass of an electron is considerably smaller than that of a neutron. (c) An atomic mass unit (amu) is a unit of mass. (d) One amu is equal to 1 gram. (e) The protons and neutrons of an atom are found in the nucleus. (I) The electrons of an atom are found in the space surrounding the nucleus. (g) All atoms of the same element have the same number of protons. (h) All atoms of the same element have the same number of electrons. (i) Electrons and protons repel each other. (j) The size of an atom is approximately the size of its nucleus. (k) The mass number of an atom is the sum of the numbers of protons and neutrons in the nucleus of that atom. (1) For most atoms, their mass number is the same as their atomic number. (m) The three isotopes of hydrogen (hydrogen-i, hydrogen-2, and hydrogen-3) differ only in the number of neutrons in the nucleus. (n) Hydrogen-i has one neutron in its nucleus, hydrogen-2 has two neutrons in its nucleus, and hydrogen-3 has three neutrons. (o) All isotopes of an element have the same number of electrons. (p) Most elements found on Earth are mixtures of isotopes. (q) The atomic weight of an element given in the Periodic Table is the weighted average of the masses of its isotopes found on Earth. (r) The atomic weights of most elements are whole numbers. (s) Most of the mass of an atom is found in its nucleus. (t) The density of a nucleus is its mass number expressed in grams.

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Introduction to General, Organic a...

11th Edition
Frederick A. Bettelheim + 4 others
Publisher: Cengage Learning
ISBN: 9781285869759
BuyFind

Introduction to General, Organic a...

11th Edition
Frederick A. Bettelheim + 4 others
Publisher: Cengage Learning
ISBN: 9781285869759

Solutions

Chapter
Section
Chapter 2, Problem 2.21P
Textbook Problem

2-21 Answer true or false.

(a) A proton and an electron have the same mass but opposite charges.

(b) The mass of an electron is considerably smaller than that of a neutron.

(c) An atomic mass unit (amu) is a unit of mass.

(d) One amu is equal to 1 gram.

(e) The protons and neutrons of an atom are found in the nucleus.

(I) The electrons of an atom are found in the space surrounding the nucleus.

(g) All atoms of the same element have the same number of protons.

(h) All atoms of the same element have the same number of electrons.

(i) Electrons and protons repel each other.

(j) The size of an atom is approximately the size of its nucleus.

(k) The mass number of an atom is the sum of the numbers of protons and neutrons in the nucleus of that atom.

(1) For most atoms, their mass number is the same as their atomic number.

(m) The three isotopes of hydrogen (hydrogen-i, hydrogen-2, and hydrogen-3) differ only in the number of neutrons in the nucleus.

(n) Hydrogen-i has one neutron in its nucleus, hydrogen-2 has two neutrons in its nucleus, and hydrogen-3 has three neutrons.

(o) All isotopes of an element have the same number of electrons.

(p) Most elements found on Earth are mixtures of isotopes.

(q) The atomic weight of an element given in the Periodic Table is the weighted average of the masses of its isotopes found on Earth.

(r) The atomic weights of most elements are whole numbers.

(s) Most of the mass of an atom is found in its nucleus.

(t) The density of a nucleus is its mass number expressed in grams.

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Chapter 2 Solutions

Introduction to General, Organic and Biochemistry
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Ch. 2 - 2-11 Name these elements (try not to look at a...Ch. 2 - 2-12 The elements game, Part 1. Name and give the...Ch. 2 - 2-13 The elements game. Part II. Name and give the...Ch. 2 - 2-14 The elements game, Part III. Give the names...Ch. 2 - 2-15 Write the formulas of compounds in which the...Ch. 2 - 2-16 Write the formulas of compounds in which the...Ch. 2 - 2-17 How does Dalton’s atomic theory explain: (a)...Ch. 2 - 2-18 When 2.16 g of mercuric oxide is heated, it...Ch. 2 - 2-19 The compound carbon monoxide contains 42.9%...Ch. 2 - 2-20 Calculate the percentage of hydrogen and...Ch. 2 - 2-21 Answer true or false. (a) A proton and an...Ch. 2 - 2-22 Where in an atom are these subatomic...Ch. 2 - 2-23 It has been said, “The number of protons...Ch. 2 - 2-24 What is the mass number of an atom with: (a)...Ch. 2 - 2-25 Name and give the symbol for each element in...Ch. 2 - 2-26 Given these mass numbers and number of...Ch. 2 - 2-27 If each atom in Problem 2-26 acquired two...Ch. 2 - 2-28 How many neutrons are in: (a) a carbon atom...Ch. 2 - 2-29 How many protons and how many neutrons does...Ch. 2 - 2.30 How many neutrons and protons are in each...Ch. 2 - 2-31 Tin-118 is one of the isotopes of tin. Name...Ch. 2 - 2-32 What is the difference between atomic number...Ch. 2 - 2-33 Define: (a) Ion (b) IsotopeCh. 2 - 2-34 There are only two naturally occurring...Ch. 2 - 2-35 The two most abundant naturally occurring...Ch. 2 - 2-36 Another isotope of carbon, carbon-14, occurs...Ch. 2 - 2-37 The isotope carbon-11 does not occur in...Ch. 2 - 2-38 Other isotopes used in PET imaging are...Ch. 2 - 2-39 Americium-241 is used in household smoke...Ch. 2 - 2-40 In dating geological samples, scientists...Ch. 2 - 2-41 Answer true or false. (a) Mendeleyev...Ch. 2 - 2-42 How many metals, metalloids, and nonmetals...Ch. 2 - 2-43 Which group(s) of the Periodic Table...Ch. 2 - 2-44 Which period(s) in the Periodic Table...Ch. 2 - 2-45 Group the following element8 according to...Ch. 2 - 2-46 Which are transition elements? (a) Pd (b) K...Ch. 2 - 2-47 Which element in each pair is more metallic?...Ch. 2 - 2-48 Classify these elements as metals, nonmetals,...Ch. 2 - 2-49 Answer true or false. (a) To say that “energy...Ch. 2 - 2-50 How many periods of the Periodic Table have...Ch. 2 - 2-51 What is the correlation between the group...Ch. 2 - 2-52 Given your answer to Problem 2-51, write the...Ch. 2 - 2-53 Write the condensed ground-state electron...Ch. 2 - 2-54 Write the Lewis dot structure for each...Ch. 2 - 2-55 Write the condensed ground-state electron...Ch. 2 - 2-56 Write the Lewis dot structure for each...Ch. 2 - 2-57 What are the similarities and differences in...Ch. 2 - 2-58 Silicon, atomic number 14, is in Group 4A....Ch. 2 - 2-59 You are presented with a Lewis dot structure...Ch. 2 - 2-60 The electron configurations for the elements...Ch. 2 - 2-61 Answer true or false. (a) Elements in the...Ch. 2 - 2-62 Why do the elements in column 1A of the...Ch. 2 - 2-63 Answer true or false. (a) Ionization energy...Ch. 2 - 2-64 Consider the elements B, C, and N. Using only...Ch. 2 - 2-65 Account for the following observations. (a)...Ch. 2 - 2-66 Using only the Periodic Table, arrange the...Ch. 2 - 2-67 Account for the fact that the first...Ch. 2 - 2-68 Every atom except hydrogen has a series of...Ch. 2 - 2-69 (Chemical Connections 2A) Why does the body...Ch. 2 - 2-70 (Chemical Connections 2B) Which are the two...Ch. 2 - 2-71 (Chemical Connections 2C) Why is strontium-90...Ch. 2 - 2-72 (Chemical Connections 2D) Bronze is an alloy...Ch. 2 - 2-73 (Chemical Connections 2D) Copper is a soft...Ch. 2 - 2-74 Give the designations of all subshells in...Ch. 2 - 2-75 Tell whether metals or nonmetals are more...Ch. 2 - 2-76 Explain why: (a) atomic radius decreases...Ch. 2 - 2-77 Name and give the symbol of the element with...Ch. 2 - 2-78 What is the outer-shell electron...Ch. 2 - 2-79 Determine the number of protons, electrons,...Ch. 2 - 2-80 What percentage of the mass of each element...Ch. 2 - 2.81 Do isotopes of the heavy elements (for...Ch. 2 - 2-82 What is the symbol for each of the following...Ch. 2 - 2-83 The natural abundance of boron isotopes is as...Ch. 2 - 2-84 How many electrons are in the outer shell of...Ch. 2 - 2-85 The mass of a proton is 1.67 × 10-24g. The...Ch. 2 - 2-86 (a) What are the charges of an electron, a...Ch. 2 - 2-87 What is the name of this element, and how...Ch. 2 - 2-88 Based on the data presented in Figure 2-16,...Ch. 2 - 2-89 Assume that a new element has been discovered...Ch. 2 - 2-90 Explain why the sizes of atoms change when...Ch. 2 - 2-91 These are the first two ionization energy for...Ch. 2 - 2-92 Which has the largest radius: O2-, F- or F?...Ch. 2 - 2-93 Arrange the following elements in order of...Ch. 2 - 2-94 Using your knowledge of trends in element...Ch. 2 - 2-95 Name the elements in Group 3A. What does the...Ch. 2 - 2-96 Using the orbital box diagrams and the noble...Ch. 2 - 2-97 Explain why the Ca3+ ion is not found in...Ch. 2 - 2-98 Explain how the ionization energy of atoms...Ch. 2 - 2-99 A 7.12 g sample of magnesium is heated with...Ch. 2 - 2-100 A 0.100 g sample of magnesium, when combined...Ch. 2 - 2-101 Complete the following table: Symbol Atomic...Ch. 2 - 2-102 An element consists of 90.51% of an isotope...Ch. 2 - 2-103 The element silver has two naturally...Ch. 2 - 2-104 The average atomic weight of lithium is...Ch. 2 - 2-105 Suppose that you face a problem similar to...Ch. 2 - 2-106 Compare the neutron to proton ratio for the...

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