Chapter 2: The Chemistry of Life

Question 1

What is comprised of matter?

Answer 1

Any substance in the universe that has mass and occupies space

Question 2

What does matter exist as?

Answer 2

Solid, Liquid, or Gas

Question 3

What is matter made up of?

Answer 3

Atoms

Question 4

What happens when you get enough of the same atom together?

Answer 4

You have an element

Question 5

What is at the core of all atoms?

Answer 5

A nucleus

Question 6

How many subatomic particles are nucleus’ comprised of?

Answer 6

2
Protons and Neutrons

Question 7

What are protons?

Answer 7

Positively charged and 1 mass unit

Question 8

What are Neutrons?

Answer 8

No associated charge and 1 mass unit

Question 9

What orbits the nucleus?

Answer 9

Electrons, which are negatively charged and almost zero mass

Question 10

What is the Atomic Mass?

Answer 10

The number of protons + Number of neutrons

Question 11

What is the Atomic Number?

Answer 11

Number of protons, which determines the element

Question 12

What do electrons determine?

Answer 12

They determine the chemical behavior of atoms, as they are associated with energy

Question 13

What energy of position does electrons have?

Answer 13

Potential energy

Question 14

What do electrons occupy?

Answer 14

Energy levels, which are also known as electron shells, of an atom, which are complex, 3-D volumes of space called orbitals

Question 15

What is the purpose of orbitals?

Answer 15

Orbitals are where electrons are most likely to be found

Question 16

Atoms tend to be more reactive when they have
a) complete electron orbitals
b) incomplete electron orbitals

Answer 16

b) incomplete electron orbitals

Question 17

What will atoms do in order to completely fill their outermost electron shell?

Answer 17

Atoms will lose, gain, or share electrons

These actions are the basis of chemical bonding

Question 18

What happens when electrons move to a lower energy level, closer to the nucleus?

Answer 18

Energy is released

Question 19

What happens when electrons move further away from the nucleus?

Answer 19

Energy is required - intake of energy

Question 20

What are ions?

Answer 20

Atoms that have gained or lost one or more electrons

Question 21

What are isotopes?

Answer 21

Atoms that have the same number of protons but DIFFERENT numbers of neutrons

Question 22

What occurs when isotopes are unstable?

Answer 22

They break up into particles with lower atomic numbers (protons)

Known as radioactive decay

Question 23

What are some uses of radioactive isotopes?

Answer 23

Dating fossils
Medical procedures
Sterilizing food

Question 24

What can decay rapidly, do not harm the body, and can be used as tracers in medical diagnoses and studies?

Answer 24

Short-lived isotopes

Question 25

What is a molecule?

Answer 25

A molecules is a group of atoms held together by energy in the form of a chemical bond

Question 26

What are the 3 principal types of chemical bonds?

Answer 26

Ionic Covalent Hydrogen

Question 27

What are Van der Waals forces?

Answer 27

They are a kind of weak chemical attractions (not a bond) that come into play when atoms are very close to each other

Question 28

Are Van der Waals forces a) directional b) nondirectional

Answer 28

b) nondirectional

Question 29

What are ionic bonds?

Answer 29

Ionic bonds involve the attraction of opposite electrical charges

Question 30

Molecules comprised of ionic bonds are often most stable as?

Answer 30

Crystals

Question 31

What are covalent bonds?

Answer 31

Directional, strong bonds that form between two atoms when they share electrons

Question 32

The number of electrons shared varies depending on what?

Answer 32

The number of electrons shared varies depending on how many electrons the atom needs to fill its outermost electron shell

Question 33

What occurs when atoms attract the shared electrons of a covalent bond (electronegativity)?

Answer 33

This creates tiny partial negative and positive charges within the molecule, now called a polar molecule

Question 34

What are polar covalent bonds?

Answer 34

These bonds form when the shared electrons of a covalent bond spend more time in the vicinity of a particular atom

Question 35

What are nonpolar covalent bonds?

Answer 35

These bonds form when there is an equally sharing of electrons between two atoms

Question 36

What are hydrogen bonds?

Answer 36

They are weak electrical attractions between the positive end of one polar molecule and the negative end of another

Question 37

What does each atom with a partial charge act like?

Answer 37

They act like a magnet to bond weakly to another polar atom with an opposite charge

Question 38

Water is what kind of molecule? a) polar and can form bonds with each other b) non-polar and can form bonds with each other

Answer 38

a) polar and can form bonds with each other

Question 39

What can water form?

Answer 39

Water can form hydrogen bonds

Question 40

What are the 5 properties of water?

Answer 40

Heat property Ice formation High heat of vaporization Cohesion High polarity

Question 41

What is Heat Storage?

Answer 41

Water heats up more slowly than other compounds and holds its temperature longer

Question 42

Why must water require high amounts of energy to vaporize?

Answer 42

Because hydrogen bonds must be broken

Question 43

What occurs when water vaporizes?

Answer 43

It takes the heat energy with it, allowing for evaporative cooling

Question 44

What is Ice Formation?

Answer 44

Water molecules move around each other with hydrogen bonds breaking and forming, but, as temperatures drop, the movement of water molecules decreases, allowing hydrogen bonds to stabilize, holding individual molecules further apart

Question 45

What is High Heat of Vaporization?

Answer 45

If the temperature if high enough, many hydrogen bonds break in water, with the result that liquid is changed into vapor

Question 46

What is Cohesion?

Answer 46

The molecular attraction between the surfaces of like bodies in contact, such as that between water molecules and other water molecules "Because water molecules are very polar, they are attracted to other polar molecules - hydrogen bonds bind polar molecules to each other. When the other polar molecule is another water molecule, this attraction is called cohesion"

Question 47

What is High Polarity?

Answer 47

Water molecules in solution always tend to form the maximum number of hydrogen bonds possible Polar molecules form hydrogen bonds and are attracted to water molecules

Question 48

What is adhesion?

Answer 48

When polar molecules other than water stick to a water molecule

Question 49

What is an example of high heat of vaporization?

Answer 49

Sweating cools the human body off because, as the sweat evaporates, it takes energy with it, in the form of heat, cooling the body

Question 50

What does Hydrophilic mean?

Answer 50

Describes polar molecules, which form hydrogen bonds with water and therefore are soluble in water Water Loving

Question 51

What does Soluble mean?

Answer 51

Refers to polar molecules that dissolve in water and are surrounded by a hydration shell

Question 52

What is a hydration shell?

Answer 52

A shell of water molecules that prevents the ions from reallocating with the object

Question 53

What does Hydrophobic mean?

Answer 53

Describes non-polar molecules, which do not form hydrogen bonds with water and therefore are not soluble in water Water Hating

Question 54

What is produced when a covalent bond within a water molecule spontaneously breaks?

Answer 54

This produces a positively charged hydrogen ion (H+) and a negatively charged hydroxide ion (OH-)

Question 55

How can the amount of ionized hydrogen from water in a solution be measured?

Answer 55

Measured as pH

Question 56

What is the pH scale?

Answer 56

A logarithmic, which means that a pH scale different of 1 unit actually represents a 10-fold change in hydrogen ion concentration

Question 57

What is the pH of pure water?

Answer 57

7

Question 58

What is an acid?