Chapter 2

Question 1

All living things consist of 1), which is
anything that occupies space and has 2).
2) is the amount of matter in any object, which does not change.

Answer 1

1) matter 2)mass

Question 2

? , the force of

gravity acting on matter, does change.

Answer 2

Weight

Question 3

All forms of matter—both living

and nonliving—are made up of a limited number of building blocks called ?.

Answer 3

chemical elements

Question 4

Each named element is designated by a ?, one or two letters of the element’s name in English, Latin, or another language. Examples of chemical symbols are H for hydrogen, C for carbon, O for oxygen, N for nitrogen,
Ca for calcium, and Na for sodium .

Answer 4

chemical symbol

Question 5

Twenty-six different chemical elements normally are present in your body. Just four elements, called the ?, constitute about 96% of the body’s mass: oxygen, carbon, hydrogen, and nitrogen.

Answer 5

major elements

Question 6

Eight others elements, called ? , contribute about 3.6% to the body’s mass:calcium, phosphorus (P), potassium (K), sulfur (S), sodium, chlorine (Cl),magnesium (Mg), and iron (Fe; ferrum= iron).

Answer 6

the lesser elements,

Question 7

An additional 14 elements—

the ? —are present in tiny amounts.

Answer 7

trace elements

Question 8

Each element is made up of ? the smallest units of matter that retain the properties and characteristics of the element.

Answer 8

atoms

Question 9

Dozens of different ? compose individual atoms.

Answer 9

subatomic particles

Question 10

The dense central core of an atom is its 1). Within the nucleus are positively charged 2) and uncharged (neutral) 3). The tiny, negatively charged 4) move about in a large space surrounding the nucleus.

Answer 10

1) nucleus 2)protons (p+) 3) neutrons (n0) 4) electrons (e−)

Question 11

Even though their exact positions cannot be predicted, specific groups of electrons are most likely to move about within certain regions around the nucleus. These regions, called ?, may be depicted as simple circles around the nucleus.

Answer 11

electron shells

Question 12

The number of protons in the nucleus of an atom is an atom’s?

Answer 12

atomic number

Question 13

The ? of an atom is the sum of its protons and neutrons.

Answer 13

mass number

Question 14

? are atoms of an element that have different numbers of neutrons and therefore different mass numbers.

Answer 14

Isotopes

Question 15

Certain isotopes called ? are unstable; their nuclei decay (spontaneously change) into a stable configuration.

Answer 15

radioactive isotopes (radioisotopes)

Question 16

The ? of an isotope is the time required for half of the radioactive atoms in a sample of that isotope to
decay into a more stable form.

Answer 16

half-life

Question 17

The standard unit for measuring the mass of atoms and their subatomic particles is a ?, also known as an atomic mass unit (amu).

Answer 17

dalton

Question 18

The ? of an element is the average mass of all

its naturally occurring isotopes.

Answer 18

atomic mass (also called the atomic weight)

Question 19

A ? is a substance that contains atoms of two or

more different elements.

Answer 19

compound

Question 20

A ? is an atom or group of atoms with an

unpaired electron in the outermost shell.

Answer 20

free radical

Question 21

If an atom either gives up or gains electrons, it becomes an ?. An ? is an atom that has a positive or negative charge because it has unequal numbers of protons and electrons.

Answer 21

ion

Question 22

? is the process of giving up or gaining electrons

Answer 22

Ionization

Question 23

When two or more atoms share electrons, the resulting combination is called a ?

Answer 23

molecule ; . A molecule may consist of two atoms of the same kind,such as an oxygen molecule

Question 24

The forces that hold together the atoms of a molecule or a compound are ?.

Answer 24

chemical bonds

Question 25

The likelihood that an atom will form a chemical

bond with another atom depends on the number of electrons in its outermost shell, also called the ?

Answer 25

valence shell

Question 26

The force of attraction that holds together ions with opposite charges is an ?.

Answer 26

ionic bond

Question 27

An ionic compound that breaks apart into positive and

negative ions in solution is called an ?

Answer 27

electrolyte

Question 28

When a ? forms, two or more atoms share electrons

rather than gaining or losing them.

Answer 28

covalent bond ; The larger the number of electron pairs shared between two atoms, the stronger the covalent bond.

Question 29

A ? results when two atoms share one electron pair. For example, a molecule of hydrogen forms when two hydrogen atoms share their single valence electrons which allows both atoms to have a full valence shell at least part of the time.

Answer 29

single covalent bond

Question 30

A ? results when two atoms share two pairs of

electrons, as happens in an oxygen molecule.

Answer 30

double covalent bond

Question 31

A ? occurs when two atoms share three pairs of electrons, as in a molecule of nitrogen .

Answer 31

triple covalent bond

Question 32

In some covalent bonds, two atoms share the electrons equally—one atom does not attract the shared electrons more strongly than the other atom. This type of bond is a ?

Answer 32

nonpolar covalent bond

Question 33

In a ?, the sharing of electrons between two

atoms is unequal—the nucleus of one atom attracts the shared electrons more strongly than the nucleus of the other atom.

Answer 33

polar covalent bond ; A very important example of

a polar covalent bond in living systems is the bond between oxygen and hydrogen in a molecule of water

Question 34

A ? forms when a hydrogen atom
with a partial positive charge (δ+) attracts the partial negative charge (δ−) of neighboring electronegative atoms, most oft en larger oxygen or nitrogen atoms

Answer 34

hydrogen bond ; hydrogen bond do establish important links between molecules or between different parts of a large molecule, such as a protein or
nucleic acid

Question 35

The hydrogen bonds that link neighboring water molecules give water considerable cohesion, the tendency of like particles together. The cohesion of water molecules creates a very high ? a measure of the difficulty of stretching or breaking the surface of a liquid.

Answer 35

surface tension

Question 36

A ? occurs when new bonds form or old bonds break between atoms.

Answer 36

chemical reaction

Question 37

? is the capacity to do work.

Answer 37

Energy

Question 38

Two principal forms of energy
are 1), energy stored by matter due to its position,
and 2) the energy associated with matter in motion

Answer 38

1) potential energy 2) kinetic energy,

Question 39

? is a form of potential energy that is stored in the bonds of compounds and molecules.

Answer 39

Chemical energy

Question 40

Although energy can be neither created nor

destroyed, it may be converted from one form to another. This principle is known as the ?

Answer 40

law of conservation of energy

Question 41

Chemical bonds represent stored chemical energy, and chemical reactions occur when new bonds are formed or old bonds are broken between atoms. The overall reaction may either release energy or absorb energy. 1) release more energy than they absorb. By contrast, 2)
absorb more energy than they release.

Answer 41

1) Exergonic reactions 2) endergonic reactions

Question 42

The collision energy needed to break the chemical bonds of the reactants is called the ? of the reaction .

Answer 42

activation energy

Question 43

? : The more particles of matter present in a confined

space, the greater the chance that they will collide.

Answer 43

Concentration

Question 44

?: As ? rises, particles of matter move about

more rapidly.

Answer 44

Temperature

Question 45

? are chemical compounds that speed up chemical reactions by lowering the activation energy needed for a reaction to occur

Answer 45

Catalysts