Question 1

Refer to the following figure to answer the questions below.
 
-How many electrons will a single atom of sulfur with no charge and no bonds have in its valence shell?
A) 6
B) 8
C) 16
D) 32

Accepted Answer

A single atom of sulfur has six electrons in its valence shell, as it is located in group 16 of the periodic table.

Question 2

Refer to the following figure to answer the questions below.
 
-Oxygen has an atomic number of 8 and, most commonly, a mass number of 16. Thus, what is the atomic mass of an oxygen atom?
A) approximately 8 grams
B) approximately 8 daltons
C) approximately 16 grams
D) approximately 16 daltons

Accepted Answer

The atomic mass of an atom is roughly equal to its mass number, which for most oxygen atoms is 16. This is best expressed in daltons, a unit of mass used for atoms and molecules.

Question 3

Refer to the following figure (first three rows of the periodic table) to answer the questions below.
 
-Which pair of elements would likely have similar valency and thus similar chemical behavior?
A) nitrogen and phosphorus
B) carbon and nitrogen
C) sodium and chlorine
D) hydrogen and helium

Accepted Answer

Nitrogen and phosphorus are in the same group of the periodic table (group 15), meaning they have the same number of valence electrons and similar valency. This leads to similar chemical behavior. Carbon and nitrogen are in different groups and have different valencies. Sodium and chlorine are in different periods and have different valencies. Hydrogen and helium are in different groups and have vastly different properties.

Question 4

Atoms have no electric charge because they have ________.
A) uncharged neutrons in their nuclei
B) an equal number of protons and neutrons
C) an equal number of protons and electrons
D) an equal number of charged and uncharged subatomic particles

Accepted Answer

Atoms have no electric charge because they have an equal number of protons (positively charged particles) and electrons (negatively charged particles). The charges balance out, resulting in a neutral overall charge. The presence of uncharged neutrons in the nucleus or an equal number of charged and uncharged subatomic particles does not directly affect the overall electric charge of the atom.

Question 5

Refer to the following figure to answer the questions below.
 
-How many electrons are present in a Phosphorus 3+ atom?
A) 16
B) 12
C) 19
D) 34

Accepted Answer

A neutral phosphorus atom has 15 electrons. When it loses 3 electrons to form a 3+ ion, it has 12 electrons remaining.

Question 6

a(n. ________ has charge but negligible mass, whereas a(n) ________ has mass but no charge.
A) proton; neutron
B) neutron; proton
C) neutron; electron
D) electron; neutron

Accepted Answer

An electron has charge but negligible mass, whereas a neutron has mass but no charge.

Question 7

Elements ⁷²Zn, ⁷⁵As, and ⁷⁴Ge have the ________.
A) same number of protons
B) same number of protons and electrons
C) same number of neutrons
D) same number of neutrons and electrons

Accepted Answer

The number of neutrons is calculated by subtracting the atomic number from the mass number. All three elements have 41 neutrons (72-31 for Zn, 75-33 for As, and 74-32 for Ge).

Question 8

Which of the following statements is TRUE?
A) Carbon, hydrogen, oxygen, and calcium are the most abundant elements of living matter.
B) Some naturally occurring elements are toxic to organisms.
C) All life requires the same essential elements.
D) A patient suffering from a goiter should not consume seafood.

Accepted Answer

Some naturally occurring elements such as lead, mercury, and arsenic can be toxic to organisms. Choice A is incorrect because calcium is not among the top four abundant elements in living matter. Choice C is incorrect because different organisms require different essential elements. Choice D is incorrect because a goiter is often caused by a lack of iodine, which is commonly found in seafood.

Question 9

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants?
A) calcium
B) iodine
C) sodium
D) phosphorus

Accepted Answer

Iodine is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants. It is necessary for the synthesis of thyroid hormones, which regulate the metabolism and growth of the body. Calcium and sodium are essential for all organisms, while phosphorus is required by all living cells for energy transfer and nucleic acid synthesis.

Question 10

Refer to the following figure (first three rows of the periodic table) to answer the questions below.
 
-What element does not prefer to react with other elements?
A) hydrogen
B) helium
C) beryllium
D) both hydrogen and beryllium

Accepted Answer

Helium (He) is a noble gas and does not easily react with other elements, making it a non-reactive element.

Question 11

In a chemical reaction, the element ¹³Al will most preferably ________.
A) lose three electrons and become positively charged
B) gain five electrons and become negatively charged
C) lose five electrons and become positively charged
D) gain three electrons and become positively charged

Accepted Answer

Aluminum (¹³Al) has three electrons in its outer shell and will most likely lose these three electrons to achieve a stable electron configuration, becoming positively charged (Al³⁺).

Question 12

The atomic number of nitrogen is 7. Nitrogen-15 has a greater mass number than nitrogen-14 because the atomic nucleus of nitrogen-15 contains ________.
A) 7 neutrons
B) 8 neutrons
C) 8 protons
D) 15 protons

Accepted Answer

Nitrogen-15 has a greater mass number since it contains 8 neutrons in addition to the 7 protons that all nitrogen atoms have. Nitrogen-14 has only 7 neutrons, making it lighter than nitrogen-15. Option A and C are incorrect because they both refer to the number of protons and neutrons in nitrogen-7, not nitrogen-15. Option D suggests a nucleus containing 15 protons, which would not be nitrogen but another element entirely.

Question 13

The left to right order of elements in the periodic table is based on their ________.
A) atomic mass
B) atomic number
C) electric charge of the atom
D) the number of neutrons

Accepted Answer

The left to right order of elements in the periodic table is based on their atomic number. The atomic number is the number of protons in the nucleus of an atom, which determines the element's identity. Elements are arranged in order of increasing atomic number from left to right in rows called periods.

Question 14

Can the atomic mass of an element vary?
A) No, it is fixed; otherwise a new element will be formed.
B) Yes. Adding or losing electrons will substantially change the atomic mass.
C) Yes. Adding or losing protons will change the atomic mass without forming a different element.
D) Yes. Adding or losing neutrons will change the atomic mass without forming a different element.

Accepted Answer

The atomic mass of an element can vary when neutrons are added or lost. This is because the atomic mass is the sum of the number of protons and neutrons in the nucleus of an atom, and changing the number of neutrons will change the mass without changing the type of element. Adding or losing electrons will change the charge of the atom, but not the atomic mass. Adding or losing protons will change the atomic number, creating a new element with a different atomic mass.

Question 15

Molybdenum has an atomic number of 42. Several common isotopes exist, with mass numbers from 92-100. Which of the following can be true?
A) Molybdenum atoms can have between 50 and 58 neutrons.
B) Molybdenum atoms can have between 50 and 58 protons.
C) Molybdenum atoms can have between 50 and 58 electrons.
D) Isotopes of molybdenum have different numbers of electrons.

Accepted Answer

Molybdenum has an atomic number of 42, which means it has 42 protons in its nucleus. The different isotopes of molybdenum have mass numbers ranging from 92-100, which corresponds to the number of protons plus neutrons in the nucleus. Therefore, the number of neutrons in molybdenum isotopes can range from 50 (mass number 92-42=50) to 58 (mass number 100-42=58). Protons and electrons, on the other hand, are normally identical in number in electrically neutral atoms. Therefore, B and C are not correct choices. D is also not correct as isotopes only differ in the number of neutrons, not electrons.

Question 16

Carbon-14 has the same ________.
A) atomic number and atomic mass as carbon-12
B) atomic number and thus number of neutrons as carbon-13
C) atomic mass as both carbon-12 and carbon-13
D) number of protons but more neutrons than carbon-12

Accepted Answer

Carbon-14 has the same number of protons (6) as carbon-12 and carbon-13, but it has more neutrons (8 instead of 6 or 7) than both of these isotopes. Therefore, option D is the best answer.

Question 17

Which of the following are compounds?
A) H₂O, O₂, and CH₄
B) H₂O and O₂
C) O₂ and CH₄
D) H₂O and CH₄, but not O₂

Accepted Answer

Compounds are substances formed from two or more different elements chemically bonded together. H₂O (water) and CH₄ (methane) are compounds, while O₂ is a molecule of a single element (oxygen) and not a compound.

Question 18

A neutral atom has two, eight, eight electrons in its first, second, and third energy levels. This information ________.
A) does not tell us about the atomic number of the element
B) does not tell us about the chemical properties of the element
C) does not tell us about the atomic mass of the element
D) does not tell us about the size of the element

Accepted Answer

The atomic mass of an element is determined by the number of protons and neutrons in its nucleus, not by the distribution of electrons in its energy levels.

Question 19

About 25 of the 92 natural elements are known to be essential to life. Which 4 of these 25 elements make up approximately 96% of living matter?
A) carbon, sodium, hydrogen, nitrogen
B) carbon, oxygen, phosphorus, hydrogen
C) oxygen, hydrogen, calcium, nitrogen
D) carbon, hydrogen, nitrogen, oxygen

Accepted Answer

The four elements that make up approximately 96% of living matter are carbon, hydrogen, nitrogen, and oxygen. Option D lists these four elements. Option A includes sodium, which is not one of the four most abundant elements in living matter. Option B includes phosphorus, which is important but not as abundant as the four listed in option D. Option C includes calcium, which is only present in trace amounts in living matter.

Question 20

An ion with six protons, seven neutrons, and a charge of 2+ has an atomic number of ________.
A) four
B) five
C) six
D) seven

Accepted Answer

The atomic number corresponds to the number of protons in the nucleus, so an ion with six protons has an atomic number of 6. The fact that the ion has a 2+ charge means that it has lost two electrons, which does not affect the atomic number. The number of neutrons affects the isotope of an element, but not its atomic number. Therefore, the answer is (C) six.

Quiz 2: The Chemical Context of Life

Refer to the following figure to answer the questions below. -How many electrons will a single atom of sulfur with no charge and no bonds have in its valence shell?

Refer to the following figure to answer the questions below. -Oxygen has an atomic number of 8 and, most commonly, a mass number of 16. Thus, what is the atomic mass of an oxygen atom?

Refer to the following figure (first three rows of the periodic table) to answer the questions below. -Which pair of elements would likely have similar valency and thus similar chemical behavior?

Atoms have no electric charge because they have ________.

Refer to the following figure to answer the questions below. -How many electrons are present in a Phosphorus 3+ atom?

a(n. has charge but negligible mass, whereas a(n) has mass but no charge.

Elements ⁷²Zn, ⁷⁵As, and ⁷⁴Ge have the ________.

Which of the following statements is TRUE?

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants?

Refer to the following figure (first three rows of the periodic table) to answer the questions below. -What element does not prefer to react with other elements?

In a chemical reaction, the element ¹³Al will most preferably ________.

The atomic number of nitrogen is 7. Nitrogen-15 has a greater mass number than nitrogen-14 because the atomic nucleus of nitrogen-15 contains ________.

The left to right order of elements in the periodic table is based on their ________.

Can the atomic mass of an element vary?

Molybdenum has an atomic number of 42. Several common isotopes exist, with mass numbers from 92-100. Which of the following can be true?

Carbon-14 has the same ________.

Which of the following are compounds?

A neutral atom has two, eight, eight electrons in its first, second, and third energy levels. This information ________.

About 25 of the 92 natural elements are known to be essential to life. Which 4 of these 25 elements make up approximately 96% of living matter?

An ion with six protons, seven neutrons, and a charge of 2+ has an atomic number of ________.