Chapter 2: The Nature Of Molecules

Front 1

All matter is composed of _____.

Back 1

Atoms.

Front 2

Understanding the structure of atoms is critical to understanding the natural of ________ ________.

Back 2

Biological molecules.

Front 3

Atoms are composed of:

Back 3

Protons, neutrons, and electrons.

Front 4

Positively charged particles.

Back 4

Protons.

Front 5

Neutral particles.

Back 5

Neutrons.

Front 6

Negatively charged particles.

Back 6

Electrons.

Front 7

Protons and neutrons are located in the _______.

Back 7

Nucleus.

Front 8

Electrons are found in:

Back 8

Orbitals surrounding the nucleus.

Front 9

What is atomic number?

Back 9

The number of protons

Front 10

Every different atom has a characteristic number of protons in the:

Back 10

Nucleus.

Front 11

Atoms with the same atomic number have the same chemical properties and belong to the same ______.

Back 11

Element.

Front 12

Each proton and neutron has a max of approximately __ _________.

Back 12

1 dalton.

Front 13

The sum of protons and neutrons is the atom’s _________ _______.

Back 13

Atomic mass.

Front 14

Atoms of the same element that have different atomic mass numbers due to different numbers of neutrons:

Back 14

Isotopes.

Front 15

6 protons, 6 neutrons, 6 electrons.

Back 15

Carbon-12

Front 16

6 protons, 7 neutrons, 6 electrons

Back 16

Carbon-13

Front 17

6 protons, 8 neutrons, 6 electrons

Back 17

Carbon-14

Front 18

_______ atoms have the same number of protons and electrons.

Back 18

Neutral.

Front 19

____ are charged atoms.

Back 19

Ions.

Front 20

______ have more protons than electrons and are positively charged.

Back 20

Cations

Front 21

______ have more electrons than protons and are negatively charged.

Back 21

Anions

Front 22

Electrons are located in ______ surrounding the nucleus.

Back 22

Orbitals.

Front 23

Each orbital can only contain ____ electrons.

Back 23

2

Front 24

Electrons possess potential energy, with electrons far from the nucleus having the ______ energy.

Back 24

Most

Front 25

Loss of an electron is:

Back 25

Oxidation

Front 26

Gain of an electron is:

Back 26

Reduction.

Front 27

The electrons in the outermost energy level of an atom are the :

Back 27

Valence electrons.

Front 28

An element’s chemical properties depend on interactions between :

Back 28

Valence electrons of different atoms.

Front 29

The _______ _______ arranges all elements according to their atomic number.

Back 29

Periodic table.

Front 30

Atoms tend to establish completely-full outer energy levels.

Back 30

Octet rule.

Front 31

Atoms with ____ energy levels are less reactive than atoms with ________ energy levels.

Back 31

Full, unfilled

Front 32

There are __ naturally occurring elements.

Back 32

90

Front 33

Only __ elements are found in living organisms in substantial amounts.

Back 33

12

Front 34

Four elements make up 96.3% of human body weight:

Back 34

Carbon, hydrogen, oxygen, nitrogen.

Front 35

______ are groups of atoms held together in a stable association.

Back 35

Molecules

Front 36

______ are molecules containing more than one type of element.

Back 36

Compounds.

Front 37

Atoms are held together in molecules or compounds by _______ ______.

Back 37

Chemical bonds

Front 38

______ bonds are formed by attraction of oppositely charged ions.

Back 38

Ionic

Front 39

________ bonds form when atoms share 2 or more valence electrons.

Back 39

Covalent

Front 40

Covalent bond strength depends on the number of _____ pairs shared by the atoms.

Back 40

Electron. Single bond < double bond < triple bond

Front 41

_______________ is an atom’s affinity for electrons.

Back 41

Electronegativity.

Front 42

Equal sharing of electrons

Back 42

Nonpolar covalent bonds.

Front 43

Unequal sharing of electrons

Back 43

Polar covalent bonds.

Front 44

Chemical reactions involve the formation or:

Back 44

Breaking of chemical bonds

Front 45

Whether a chemical reaction occurs is influenced by:

Back 45

Temperature, concentration of reactants and products, and availability of a catalyst.

Front 46

Chemical reactions are written with the:

Back 46

Reactants first, followed by the products.

Front 47

All living organisms are dependent on:

Back 47

Water.

Front 48

The most important property of water is the ability to form:

Back 48

Hydrogen bonds

Front 49

Within a water molecule, the bonds between oxygen and hydrogen are :

Back 49

Highly polar.

Front 50

Partial electrical charges develop within a water molecule:

Back 50

Oxygen is partially negative, hydrogen is partially positive.

Front 51

These can form between water molecules or between water and another charged molecule.

Back 51

Hydrogen bonds.

Front 52

The polarity of water causes it to be :

Back 52

cohesive and adhesive.

Front 53

Water molecules stick to other water molecules by hydrogen bonding.

Back 53

Cohesion.

Front 54

Water molecules stick to other polar molecules by hydrogen bonding.

Back 54

Adhesion.

Front 55

Water has a high specific heat.

Back 55

A large amount of energy is required to change the temperature of water.

Front 56

Water has a high heat of vaporization.

Back 56

The evaporation of water from a surface causes cooling of that surface.

Front 57

Solid water is less dense than liquid water.

Back 57

Bodies of water freeze from the top down.

Front 58

Water is a good solvent.

Back 58

Water dissolved polar molecules and ions.

Front 59

Water-loving

Back 59

Hydrophilic

Front 60

Water-fearing

Back 60

Hydrophobic

Front 61

Hydrogen ion (H+1) is the basis of the __ ____.

Back 61

pH scale.

Front 62

Greater H+1 concentration =

Back 62

Lower pH (acidic)

Front 63

A chemical that releases H+1 ions.

Back 63

Acid.

Front 64

A chemical that accepts H+1 ions.

Back 64

Base.

Front 65

A chemical that accepts/releases H+1 as necessary to keep pH constant.

Back 65

Buffer.

Front 66

Most biological buffers consist of a pair of molecules, one an ______ and one a _____.

Back 66

Acid and a base.