Chapter 2

Question 1

All organisms are made of chemicals

Answer 1

T

Question 2

All life is composed of chemical substances, includes water, DNA, proteins, and other organic molecules. Each of these composed of atoms.

Answer 2

T

Question 3

substance that takes up space and is made of atoms, such as organisms, rocks, oceans, and gases in the air.

Answer 3

matter

Question 4

ability to do work. work meaning moving matter.

Answer 4

energy

Question 5

heat, light, and chemical bonds are all forms of energy.

Answer 5

Energy

Question 6

a pure substance that cannot be broken down by chemical means into other substances. atoms containing a number of protons.

Answer 6

element

Question 7

a chart that arranges the elements in such a way their chemical properties repeat in each vertical column.

Answer 7

periodic table

Question 8

an element that an organism requires in large amounts. makes up the vast majority of every living cell. such as carbon, hydrogen, oxygen, and nitrogen.

Answer 8

bulk element

Question 9

an element that an organism requires in small amounts. such as iron and zinc.

Answer 9

trace elements

Question 10

thyroid gland requires the trace element iodine. if the diet does not supply enough iodine, the thyroid may become enlarged, forming a growth called a goiter in the neck.

Answer 10

T

Question 11

red blood cells require iron to carry oxygen to the body’s tissues. iron deficient diet can cause anemia, which is a decline in the number of red blood cells.

Answer 11

T

Question 12

the smallest piece of an element. composed of three particles, includes protons, neutrons, and electrons.

Answer 12

atom

Question 13

a particle in an atom’s nucleus, carries a positive charge. mass of 1

Answer 13

proton

Question 14

a particle in an atom’s nucleus, uncharged (neutral charge). mass of 1

Answer 14

neutrons

Question 15

a particle outside surrounding the atom’s nucleus, a negative charge, essentially weightless. mass of 0

Answer 15

electrons

Question 16

central part of an atom

Answer 16

nucleus (atom)

Question 17

number of protons in an atom’s nucleus

Answer 17

atomic number

Question 18

when the number of protons equals the number of electrons, the atom is neutral and has no net charge.

Answer 18

T

Question 19

an atom or group of atoms that as lost or gained electrons, giving it a net negative charge or positive charge.

Answer 19

ion

Question 20

H+, Na+, K+

Answer 20

positive charged ion (cation)

Question 21

OH-, CI-

Answer 21

negative charged ion (anion)

Question 22

transmission of messages in the nervous system, also forms ionic bonds

Answer 22

ions

Question 23

total number of protons and neutrons in an atom’s nucleus

Answer 23

atom’s mass number

Question 24

subtracting the atomic number from the mass number, gives the number of neutrons in an atom.

Answer 24

T

Question 25

an element have the same number of protons but not exactly the same number of neutrons.

Answer 25

T

Question 26

any of the forms of an element, each having a different number of neutrons in the nucleus.

Answer 26

isotope

Question 27

average mass of all atoms of an element. close to the mass number.

Answer 27

atomic weight

Question 28

atom that emits particles or rays as its nucleus disintegrates, break down into more stable forms.

Answer 28

radioactive isotopes

Question 29

used in medicine and science, from detecting broken bones to the ages of fossils. excessive radiation can lead to radiation sickness, can cause cancer.

Answer 29

radioactive isotopes

Question 30

two or more atoms joined by chemical bonds

Answer 30

molecule

Question 31

a molecule composed of two or more different elements

Answer 31

compound

Question 32

volume of space where a particular electron is likely to be

Answer 32

orbital

Question 33

group of electron orbitals that share the same energy level

Answer 33

energy shells

Question 34

outermost occupied energy shell of an atom

Answer 34

valence shell

Question 35

an atom's tendency to attract electrons

Answer 35

electronegativity

Question 36

attractive force that holds atoms together

Answer 36

chemical bond

Question 37

an atom is most stable if its valence shell is full

Answer 37

T

Question 38

attraction between oppositely charged ions

Answer 38

ionic bonds

Question 39

type of chemical bond in which two atoms share electrons

Answer 39

covalent bond

Question 40

a covalent bond in which electrons are attracted more to one atom's nucleus than to the other nucleus

Answer 40

polar covalent bond

Question 41

a covalent in which atoms share electrons equally

Answer 41

nonpolar covalent bond