OpenStax Biology 2e Chapter 2 The Chemical Foundation of Life

Which of the following statements is true? A. Acids and bases cannot mix together. B. Acids and bases will neutralize each other. C. Acids, but not bases, can change the pH of a solution. D. Acids donate hydroxide ions (OH-); bases donate hydrogen ions (H+).

B

Potassium has an atomic number of 19. What is its electron configuration? A. shells 1 and 2 are full, and shell 3 has nine electrons B. shells 1, 2 and 3 are full and shell 4 has three electrons C. shells 1, 2 and 3 are full and shell 4 has one electron D. shells 1, 2 and 3 are full and no other electrons are present

C

Which of the following statements is false? A. Molecules with the formulas CH3CH2COOH and C3H6O2 could be structural isomers. B. Molecules must have a double bond to be cis-trans isomers. C. To be enantiomers, a molecule must have at least three different atoms or groups connected to a central carbon. D. To be enantiomers, a molecule must have at least four different atoms or groups connected to a central carbon.

C

How many neutrons do carbon-12 and carbon-13 have, respectively?

Carbon-12: 6 Neutrons Carbon-13: 7 Neutrons

Why are hydrogen bonds and van der Waals interactions necessary for cells?

Hydrogen bonds are also responsible for zipping together the DNA double helix. The van der Waals interactons—along with ionic, covalent, and hydrogen bonds—contribute to the three-dimensional structure of the proteins in our cells that is necessary for their proper function.

atom

the smallest unit of matter that retains all of the chemical properties of an element

mass number

total number of protons and neutrons in an atom

atomic number

total number of protons in an atom

molecule

two or more atoms chemically bonded together

polar covalent bond

type of covalent bond that forms as a result of unequal electron sharing, resulting in creating slightly positive and negative charged molecule regions

nonpolar covalent bond

type of covalent bond that forms between atoms when electrons are shared equally between them

covalent bond

type of strong bond formed between two atoms of the same or different elements; forms when electrons are shared between atoms

neutron

uncharged particle that resides in an atom's nucleus; has a mass of one amu

van der Waals interaction

very weak interaction between molecules due to temporary charges attracting atoms that are very close together

hydrogen bond

weak bond between slightly positively charged hydrogen atoms and slightly negatively charged atoms in other molecules

sphere of hydration

when a polar water molecule surrounds charged or polar molecules thus keeping them dissolved and in solution

What makes ionic bonds different from covalent bonds?

Ionic bonds result when electrons are tranfered between atoms. Covalent bonds result when valence electrons are shared between atoms.

electronegativity

ability of some elements to attract electrons (often of hydrogen atoms), acquiring partial negative charges in molecules and creating partial positive charges on the hydrogen atoms

calorie

amount of heat required to change the temperature of one gram of water by one degree Celsius

organic molecule

any molecule containing carbon (except carbon dioxide)

ion

atom or chemical group that does not contain equal numbers of protons and electrons

adhesion

attraction between water molecules and other molecules

We call a molecule that binds up excess hydrogen ions in a solution a(n) ________.

base

atomic mass

calculated mean of the mass number for an element's isotopes

evaporation

change from liquid to gaseous state at a body of water's surface, plant leaves, or an organism's skin

ionic bond

chemical bond that forms between ions with opposite charges (cations and anions)

nucleus

core of an atom; contains protons and neutrons

Each carbon molecule can bond with as many as________ other atom(s) or molecule(s).

four

functional group

group of atoms that provides or imparts a specific function to a carbon skeleton

heat of vaporization of water

high amount of energy required for liquid water to turn into water vapor

Which type of bond represents a weak chemical bond?

hydrogen bond

chemical bond

interaction between two or more of the same or different atoms that results in forming molecules

cohesion

intermolecular forces between water molecules caused by the polar nature of water; responsible for surface tension

electrolyte

ion necessary for nerve impulse conduction, muscle contractions, and water balance

radioisotope

isotope that emits radiation comprised of subatomic particles to form more stable elements

Atoms that vary in the number of neutrons found in their nuclei are called ________.

isotopes

hydrocarbon

molecule that consists only of carbon and hydrogen

acid

molecule that donates hydrogen ions and increases the concentration of hydrogen ions in a solution

base

molecule that donates hydroxide ions or otherwise binds excess hydrogen ions and decreases the hydrogen ions' concentration in a solution

product

molecule that is result of chemical reaction

reactant

molecule that takes part in a chemical reaction

isomers

molecules that differ from one another even though they share the same chemical formula

electron transfer

movement of electrons from one element to another; important in creating ionic bonds

electron

negatively charged subatomic particle that resides outside of the nucleus in the electron orbital; lacks functional mass and has a negative charge of -1 unit

capillary action

occurs because water molecules are attracted to charges on the inner surfaces of narrow tubular structures such as glass tubes, drawing the water molecules to the tubes' sides

element

one of 118 unique substances that cannot break down into smaller substances; each element has unique properties and a specified number of protons

isotope

one or more forms of an element that have different numbers of neutrons

periodic table

organizational chart of elements indicating each element's atomic number and atomic mass; provides key information about the elements' properties

valence shell

outermost shell of an atom

litmus paper (also

pH paper), filter paper treated with a natural water-soluble dye that changes its color as the pH of the environment changes in order to use it as a pH indicator

proton

positively charged particle that resides in the atom's nucleus; has a mass of one amu and a charge of +1

chemical reaction

process leading to rearranging atoms in molecules

dissociation

release of an ion from a molecule such that the original molecule now consists of an ion and the charged remains of the original, such as when water dissociates into H+ and OH-

octet rule

rule that atoms are most stable when they hold eight electrons in their outermost shells

pH scale

scale ranging from zero to 14 that is inversely proportional to the hydrogen ions' concentration in a solution

balanced chemical equation

statement of a chemical reaction with the number of each type of atom equalized for both the products and reactants

equilibrium

steady state of relative reactant and product concentration in reversible chemical reactions in a closed system

solvent

substance capable of dissolving another substance

compound

substance composed of molecules consisting of atoms of at least two different elements

buffer

substance that prevents a change in pH by absorbing or releasing hydrogen or hydroxide ions

surface tension

tension at the surface of a body of liquid that prevents the molecules from separating; created by the attractive cohesive forces between the liquid's molecules

chemical reactivity

the ability to combine and to chemically bond with each other

specific heat capacity

the amount of heat one gram of a substance must absorb or lose to change its temperature by one degree Celsius

. If xenon has an atomic number of 54 and a mass number of 108, how many neutrons does it have?

54

Which of the following statements is not true? a. Water is polar. b. Water stabilizes temperature. c. Water is essential for life. d. Water is the most abundant molecule in the Earth's atmosphere.

D

Discuss how buffers help prevent drastic swings in pH.

They readily absorb excess H+ or OH-

Which of the following is not a functional group that can bond with carbon? a. sodium b. hydroxyl c. phosphate d. carbonyl

a