Biology Exam 1 Chapter 2

An atom has 8 protons, 8 neutrons, and 8 electrons. Another isotope of the same element might have ... a. mass number 16, atomic number 7. b. 9 protons. c. 10 neutrons. d. 7 electrons. e. All of the above.

c. 10 neutrons.

The atomic number of each atom is given to the left of each of the following elements. Which of the atoms has the same valence as carbon (12/6C)? a. 9 F fluorine b. 7 N nitrogen c. 14 Si silicon d. 10 Ne neon e. 12 Mg magnesium

c. 14 Si silicon

The atomic number of sulfur is 16, which indicates that a sulfur atom contains a. 16 protons and 16 neutrons. b. 16 neutrons. c. 16 protons. d. 8 protons and 8 neutrons. e. 8 electrons in its outermost electron shell.

c. 16 protons.

What is the mass number of an ion with 105 electrons, 157 neutrons, and a +1 charge?

263 105 + 157 + 1 = 263

Match: symbol: Charge Proton N 0 charge Neutron E -1 charge Electron P +1 charge

Proton > P > +1 charge Neutron > N > 0 charge Electron > E > -1 charge

d. All of the above.

Which statement is true of the atom shown in the diagram? a. An electron will move from the outer to the inner shell. b. The atom has more than one valence electron. c. The atom is in the excited state. d. All of the above. e. None of the above.

The innermost electron shell of an atom can hold up to _____ electrons. a. 2 b. 8 c. 1 d. 32 e. 18

a. 2

The atomic number of nitrogen is 7. Nitrogen-15 is heavier than nitrogen-14 because the atomic nucleus of nitrogen-15 contains how many neutrons? a. 8 b. 7 c. 6 d. 12 e. 14

a. 8

Which of the following is primarily responsible for the unique chemical properties of each element? a. Each element has a unique number of protons. b. Each element has a unique atomic mass. c. Each element has unique radioactive properties. d. Each element has a unique atomic number. e. Each element has a unique number of neutrons.

a. Each element has a unique number of protons.

Which statement is true of atoms? a. Electrons determine the atom's size. b. Protons attract other protons. c. Protons repel electrons. d. Most of an atom's volume is filled with matter. e. All of the above.

a. Electrons determine the atom's size.

Molybdenum has an atomic number of 42. Several common isotopes exist, with mass numbers of 92, 94, 95, 96, 97, 98, and 100. Therefore, which of the following can be true? a. Molybdenum atoms can have between 50 and 58 neutrons. b. The isotopes of molybdenum have between 50 and 58 neutrons and have different electron configurations. c. The isotopes of molybdenum have different electron configurations. d. The isotopes of molybdenum have between 50 and 58 protons and have different electron configurations. e. The isotopes of molybdenum can have between 50 and 58 protons.

a. Molybdenum atoms can have between 50 and 58 neutrons.

Which of these relationships is true of an uncharged atom? a. The number of protons is equal to the number of electrons. b. The atomic mass is equal to the number of electrons. c. The number of neutrons is equal to the number of protons. d. The number of electrons is equal to the number of neutrons. e. The atomic mass is equal to the atomic number.

a. The number of protons is equal to the number of electrons.

Atom 1 Atom 2 _1_ H _3_ H 1 1 Which of the following best describes the relationship between the atoms described in the figure? a. They are isotopes. b. They each contain 1 neutron. c. They are polymers. d. They contain 1 and 3 protons, respectively. e. They are compounds.

a. They are isotopes.

In what way are elements in the same row of the periodic table the same? a. They have the same number of electron shells. b. They have the same number of electrons in their valence shell. c. They have the same number of neutrons. d. They have the same number of protons. e. They have the same number of electrons.

a. They have the same number of electron shells.

In what way are elements in the same column of the periodic table the same? a. They have the same number of electrons in their valence shell. b. They have the same number of electron shells. c. They have the same number of protons. d. They have the same number of electrons. e. They have the same number of neutrons.

a. They have the same number of electrons in their valence shell.

A substance that cannot be broken down into other substances by ordinary chemical procedures is a(n) _____. a. element b. proton c. compound d. molecule e. isotope

a. element

A carbon atom and a hydrogen atom form what type of bond in a molecule? a. nonpolar covalent bond b. ionic bond c. polar covalent bond d. Van der Waals interaction e. hydrogen bond

a. nonpolar covalent bond

Chemists assign atoms to chemical elements by counting their ________. a. protons b. neutrons c. electrons d. isotopes

a. protons

From the atomic mass, one can deduce the number of ________ in each atom of an element. a. protons plus neutrons b. protons c. electrons d. protons plus electrons e. neutrons

a. protons plus neutrons

Dr. Jones says an atom has 3 electrons in the first shell and four electrons in the second shell. Someone should tell Dr. Jones that ... a. the first shell shouldn't have 3 electrons b. the second shell can't have 4 electrons. c. no shell can hold more than 2 electrons. d. the first shell must fill before the second shell can have electrons. e. the second shell should have 8 electrons.

a. the first shell shouldn't have 3 electrons

What determines the types of chemical reactions that an atom participates in? a. the number of electrons in the outermost electron shell b. the number of electrons in the innermost electron shell c. the number of protons it contains d. its atomic number e. its atomic mass

a. the number of electrons in the outermost electron shell

Argon has atomic number 18. Which of the following statements about argon is true? a. It has 10 electrons in its outer electron shell. b. It is inert. c. It has an atomic mass of 18 daltons. d. It has six valence electrons. e. It resides in the first column of the periodic table.

b. It is inert.

An ionic bond involves _____. a. the unequal sharing of an electron pair b. an attraction between ions of opposite charge c. water avoidance d. no atoms other than sodium and chlorine e. the sharing of a single pair of electrons

b. an attraction between ions of opposite charge

A(n) _____ refers to two or more atoms held together by covalent bonds. a. shell b. molecule c. community d. isotope e. ion

b. molecule

An ionic bond is formed when __________. a. both atoms are equally attractive to electrons b. one atom transfers an electron to another atom c. both atoms are electrically neutral d. atoms are subjected to radioactive isotopes e. both atoms are nonpolar

b. one atom transfers an electron to another atom

The type of bonding and the numbers of covalent bonds an atom can form with other atoms are determined by __________. a. the nucleus b. the number of unpaired electrons in the valence shell c. the number of protons d. the number of neutrons e. the size of the atom; smaller atoms are chemically more reactive

b. the number of unpaired electrons in the valence shell

One difference between carbon-12 ( 12/6C) and carbon-14 ( 14/6C) is that carbon-14 has a. two more protons and two more neutrons than carbon-12. b. two more neutrons than carbon-12. c. two more electrons than carbon-12. d. two more electrons and two more protons than carbon-12. e. two more protons than carbon-12.

b. two more neutrons than carbon-12.

The mass number of an atom is 15, and its atomic number is 7. The atom probably has... a. 7 units of negative charge in the nucleus. at least 15 electrons. b. about as much mass in electrons as in protons. c. 8 neutrons in the nucleus. d. 7 electrons in the nucleus.

c. 8 neutrons in the nucleus. 15 - 7 = 8

Which statement is true of the energy levels of electrons in shells? a. Electrons must lose energy to move from the first to the second shell. b. All the electrons in an atom have similar amounts of energy. c. The valence shell has higher energy than other occupied shells d. All of the above. e. None of the above.

c. The valence shell has higher energy than other occupied shells

A phrase that applies to covalent bonding and not other kinds of bonds is ... a. great strength. b. paired electrons. c. electron-sharing. d. charge attraction. e. All of the above.

c. electron-sharing.

What name is given to the bond between water molecules? a. single (nonpolar) covalent b. hydrophobic c. hydrogen d. polar covalent e. ionic

c. hydrogen

In salt, what is the nature of the bond between sodium and chlorine? a. hydrogen b. nonpolar covalent c. ionic d. polar covalent e. hydrophobic

c. ionic

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by all organisms? a. potassium b. iodine c. iron d. sodium e. calcium

c. iron

Which of the following is a trace element required by most living organisms? a. oxygen b. nitrogen c. magnesium d. hydrogen e. carbon

c. magnesium

Two atoms always represent the same element if they have ... a. the same number of particles in the nucleus. b. the same mass number. c. the same number of protons. d. the same number of electrons. e. the same number of shells.

c. the same number of protons.

Fluorine's atomic number is 9 and its atomic mass is 19. How many neutrons does fluorine have? a. 19 b. 28 c. 9 d. 10 e. 81

d. 10 19 - 9 = 10

An atom has 6 electrons in its outer shell. How many unpaired electrons does it have? a. 6 b. 0 c. 2 or 4 d. 2 e. 4

d. 2

The atoms of different phosphorus isotopes __________. a. have different atomic numbers b. have different numbers of protons c. react differently with other atoms d. have different numbers of neutrons e. have different numbers of electrons

d. have different numbers of neutrons

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? a. nitrogen b. sodium c. calcium d. iodine e. phosphorus

d. iodine

Which of the following subatomic particles always has a positive charge? a. element b. neutron c. electron d. proton e. atom

d. proton

Fluorine has an atomic number of 9 and a mass number of 19. How many electrons are needed to complete the valence shell of a fluorine atom? a. 7 b. 9 c. 3 d. 0 e. 1

e. 1

An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many protons does boron have? a. 0 b. 11 c. 16 d. 6 e. 5

e. 5

What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons? a. 12 b. -1 c. 0 d. 18 e. 6

e. 6

An atom has 6 electrons, 6 protons, and 6 neutrons. You can tell that this atom belongs to the element _____ because _____________________. a. C; it has 6 electrons. b. N; it has 6 protons. c. O; its mass number is 12. d. N; it has 6 electrons. e. C; it has 6 protons.

e. C; it has 6 protons.

The nucleus of a nitrogen atom contains 7 neutrons and 7 protons. Which of the following is a correct statement concerning nitrogen? a. The nitrogen atom has a mass number of 7 and an atomic number of 14. b. The nitrogen atom has a mass number of 14 and an atomic number of 21. c. The nitrogen atom has a mass number of 14 and an atomic number of 14. d. The nitrogen atom has a mass number of 7 and an atomic number of 21. e. The nitrogen atom has a mass number of 14 and an atomic number of 7.

e. The nitrogen atom has a mass number of 14 and an atomic number of 7.

Which of these refers to atoms with the same atomic number but different atomic masses? a. These atoms are isomers. b. These atoms have different numbers of electrons. c. These atoms have different numbers of protons. d. These atoms are different elements. e. These atoms are isotopes.

e. These atoms are isotopes.

Radioactive decay is likely to occur when ... a. atoms collide with one another. b. protons break into neutrons and electrons. c. an atom has too many electrons. d. an electron hits the nucleus. e. an atom has too many neutrons.

e. an atom has too many neutrons.

Atoms with the same number of protons but with different electrical charges _____. a. are different isotopes b. have different atomic masses c. have different atomic numbers d. have different numbers of neutrons e. are different ions

e. are different ions

About 20-25% of the 92 natural elements are known to be essential to life. Which four of these elements make up approximately 96% of living matter? a. carbon, oxygen, phosphorus, hydrogen b. carbon, oxygen, nitrogen, calcium c. carbon, sodium, hydrogen, nitrogen d. oxygen, hydrogen, calcium, nitrogen e. carbon, hydrogen, nitrogen, oxygen

e. carbon, hydrogen, nitrogen, oxygen

Two atoms that have the same mass number must have the same a. protons. b. chemical properties. c. atomic number. d. number of electrons. e. number of protons + neutrons.

e. number of protons + neutrons.

A covalent chemical bond is one in which a. outer-shell electrons of one atom are transferred to fill the inner electron shell of another atom. b. an electron from a full outer electron shell of one atom is shared so as to occupy the outer electron shell of both atoms. c. electrons are removed from one atom and transferred to another atom so that the two atoms become oppositely charged. d. protons and neutrons are shared by two atoms so as to satisfy the requirements of both atoms. e. outer-shell electrons of two atoms are shared so as to occupy the outer electron shells of both atoms.

e. outer-shell electrons of two atoms are shared so as to occupy the outer electron shells of both atoms.

Changing the number of _____ would change an atom into an atom of a different element. a. neutrons in an atom b. bonds formed by an atom c. electrons circling the nucleus of an atom d. particles in the nucleus of an atom e. protons in an atom

e. protons in an atom

Match: mass of ~1/2000 amu ____electron_____ mass of ~1 amu ____proton_____ _____neutron_____

mass of ~1 amu: neutron & proton mass of ~1/2000 amu: electron