Bio 1001-Chapter 2

base

(1) a substance capable of combining with and neutralizing H+ ions in a solution; a solution with a pH greater than 7; (2) one of the nitrogen-containing, single- or double-ringed structures that distinguishes one nucleotide from another. In DNA, the bases are adenine, guanine, cytosine, and thymine.

ion

a charged atom or molecule; an atom or molecule that either has a excess of electrons (and, hence, is negatively charged) or has lost electrons (and is positively charged)

periodic table

a chart first devised by Russian chemist Dmitri Mendeleev that includes all known elements and organizes them according to their atomic numbers in rows and their general chemical properties in columns

covalent bond

a chemical bond between atoms in which electrons are shared

ionic bond

a chemical bond formed by the electrical attraction between positively and negatively charged ions

buffer

a compound that minimizes changes in pH by reversibly taking up or releasing H+ ions

nonpolar covalent bond

a covalent bond with equal sharing of electrons

polar covalent bond

a covalent bond with unequal sharing of electrons, such that one atom is relatively negative and the other is relatively positive

solvent

a liquid capable of dissolving (uniformly dispersing) other substances in itself

free radical

a molecule containing an atom with an unpaired electron, which makes it highly unstable and reactive with nearby molecules. By removing an electron from the molecule it attacks, it creates a m new free radical and begins a chain reaction that can lead to the destruction of biological molecules crucial to life

molecule

a particle composed of one or more atoms held together by chemical bonds; the smallest particle of a compound that displays all the properties of that compound

chemical reaction

a process that forms and breaks chemical bonds that hold atoms together in molecules

electron shell

a region in an atom within which electrons orbit; each shell corresponds to a fixed energy level at a given distance from the nucleus

pH scale

a scale, with values from 0 to 14, used for measuring the relative acidity of a solution; at pH 7 a solution is neutral , pH 0 to 7 is acidic, and pH 7-14 is basic; each unit on the scale represents a 10-fold change in H+ concentration

solution

a solvent containing one or more dissolved substances (solutes)

neutron

a subatomic particle that is found in the nuclei of atoms, bears no charge, and has no mass approximately equal to that of a proton

proton

a subatomic particle that is found in the nuclei of atoms; it bears a unit of positive charge and has a relatively large mass, roughly equal to the mass of a neutron

electron

a subatomic particle, found in a electron shell outside the nucleus of an atom, that bears a unit of negative charge and very little mass

element

a substance that cannot be broken down, or converted, to a simpler substance by ordinary chemical reactions

Acid

a substance that releases hydrogen ions (H+) into solution; a solution with a pH less than 7

Copper has 29 protons, 34 neutrons, and 29 electrons. What is the atomic number of copper? a. 29 b. 34 c. 58 d. 63 e. 92

a. 29

Antioxidants have the ability to counteract the effects of highly reactive atoms called free radicals, which can damage biological molecules such as DNA. Which of the following statements is true regarding antioxidants? a. Antioxidants can be obtained in our diet by eating fruits and vegetables. b. Antioxidants are highly reactive atoms with partially filled outer electron shells. c. Antioxidants can be obtained only as vitamin supplements. d. Antioxidants can lead to cardiovascular disease. e. Antioxidants can cause aging of cells and lead to wrinkles and graying hair

a. Antioxidants can be obtained in our diet by eating fruits and vegetables.

How do the hydrogen bonds between water molecules compare to the covalent bonds within water molecules? a. They hydrogen bonds are more easily broken than the covalent bonds. b. Hydrogen bonds are betweenn two hydrogen atoms. Covalent bonds are between a hydrogen atom and an oxygen atom c. Hydrogen bonds between molecules are stronger than covalent bonds within a molecule d. The hydrogen and covalent bonds are both polar. e. They hydrogen and covalent bonds both involve electron sharing.

a. They hydrogen bonds are more easily broken than the covalent bonds.

Which of the following lists of terms is in the correct order of size, going from smallest to largest? a. electron, proton, nucleus, atom, molecule b. nucleus, electron, proton, atom, molecule c. proton, electron, nucleus, atom, molecule d. electron, proton, nucleus, molecule, atom e. molecule, atom, nucleus, proton, electron

a. electron, proton, nucleus, atom, molecule

chemical bond

an attraction between two atoms or molecules that tends to hold them together. Types of bonds include covalent, ionic, and hydrogen.

antioxidant

any molecule that reacts with free radicals, neutralizing their ability to damage biological molecules. Vitamins C and E are examples of dietary antioxidants

How are ionic and covalent bonds related? a. Electrons are shared in an ionic bond and traded completely in a covalent bond b. Ionic and covalent bonds both result in a full outer electron shell c. Ionic bonds result in positive charges. Covalent bonds result in negative charges. d. Ionic bonds are harder to break apart than covalent bonds e. Ionic bonds involve electrons. Covalent bonds involve the nucleus.

b. Ionic and covalent bonds both result in a full outer electron shell

Coffee has a pH of 5.0. Stomach acid has a pH of 2.0. How does the pH of coffee compare to that of stomach acid? a. Coffee contains more H+ ions than stomach acid. b. Stomach acid is 1,000 times more acidic than coffee. c. Coffee is three times more acidic than stomach acid. d. Coffee contains fewer OH- ions than stomach acid. e. Stomach acid is an acid; coffee is a base.

b. Stomach acid is 1,000 times more acidic than coffee.

Cancer is caused by DNA mutations. What exactly do cigarette smoke and radiation do that can cause cancer? a. Radiation causes free radicals. Cigarette smoke causes DNA damage b. Cigarette smoke and radiation both cause damage to DNA, leading to mutation. c. Cigarette smoke and radiation both cause free radicals, which damage DNA, leading to mutations. d. Cigarette smoke damages DNA, leading to free radicals. Radiation causes mutations in DNA.

c. Cigarette smoke and radiation both cause free radicals, which damage DNA, leading to mutations.

Why are hydrophobic molecules such as fats and oils unable to dissolve in watery solutions? a. Hydrophobic molecules form hydrogen bonds with one another, excluding water. b. Hydrophobic molecules have polar covalent bonds, preventing water from interacting with them. c. Hydrophobic molecules are nonpolar, so they can't form hydrogen bonds with water. Water molecules form hydrogen bonds with each other, excluding the hydrophobic molecules. d. Water molecules interact only with ionic bonds, not covalent bonds e. Hydrophobic molecules attract water molecules and form a weak bond.

c. Hydrophobic molecules are nonpolar, so they can't form hydrogen bonds with water. Water molecules form hydrogen bonds with each other, excluding the hydrophobic molecules.

Why does ice float? a. The energy contained in the hydrogen bonds of ice is greater than the energy contained in the hydrogen bonds of water. b. Ice floats because water molecules expand. c. The hydrogen bonds in solid water force the molecules farther apart from one another than the same bonds in liquid water. d. The hydrogen bonds between molecules of liquid water are stronger than those of the solid, pulling the liquid molecules closer together. e. Solids are less dense in general than their liquid form.

c. The hydrogen bonds in solid water force the molecules farther apart from one another than the same bonds in liquid water.

How does water dissolve salt? a. The partial positive charges of hydrogen form covalent bonds with a negatively charged chloride ion. b. The partial positive charges of hydrogen form covalent bonds with a negatively charged chloride ion. c. The partial positive charges of the hydrogen atoms on water surround the negative charge of a chlorine ion, effectively separating the chlorine from its bond with sodium. d. The positive charges of the oxygen atoms on water balance the partial negative charge of a sodium atom. e. The oxygen atoms of water form a polar covalent bond with the sodium atom.

c. The partial positive charges of the hydrogen atoms on water surround the negative charge of a chlorine ion, effectively separating the chlorine from its bond with sodium.

What is a hydrogen bond? a. a bond between the hydrogen and oxygen within a water molecule b. a polar bond between two hydrogen atoms in the same water molecule c. a weak bond between a slightly positive hydrogen atom and a slightly negative atom in a neighboring molecule d. a polar covalent bond between hydrogen and oxygen e. a weak bond between the hydrogen atoms in two different water molecules f. a weak bond between two slightly positively charged hydrogen atoms

c. a weak bond between a slightly positive hydrogen atom and a slightly negative atom in a neighboring molecule

In which scenario given, will the electrons have the highest energy? a. electrons in the outer shell of sulfur b. electrons in the outer shell of nitrogen c. electrons in the outer shell of potassium d. electrons in the outer shell of oxygen e. electrons in the outer shell of carbon f. electrons in the outer shell of helium

c. electrons in the outer shell of potassium

What property of an atom determines which element it is? a. the number of molecules b. the number of neutrons c. the number of protons d. the number of electrons e. the number of atoms

c. the number of protons

Which of the following solutions would contain buffers that prevent shifting pH when acids or bases are mixed with the following solutions? a. Bottled Water b. Detergents c. Coffee d. Blood

d. Blood

Because the specific heat of land is less than the specific heat of water, which of the following should be true? a. Islands should always be cooler than the mainland b. Wet or swampy soils should reach higher temperatures than dry dirt c. Land will reach a higher temperature more slowly than water, if the same amount of energy is applied to both. d. Land will always be warmer than water. e. After a warm day, the land will cool down quickly, but the water will take longer to cool down.

e. After a warm day, the land will cool down quickly, but the water will take longer to cool down.

If electrons in water molecules were equally attracted to the hydrogen and oxygen atoms, how would this affect the polar covalent bonds between the hydrogen and oxygen atoms? a. The bond would break b. The bond would become more polar. c. The bond would become covalent. d. The bond would become a hydrogen bond e. The bond would become less polar f. The bond would become ionic

e. The bond would become less polar

In water, the chemical HCO3 - acts as a buffer. In dry form, this chemical is often ionically bound to another element. Which of the following elements would be a good candidate for that element? a. hydroxide (OH-) b. carbon (C) c. chlorine (Cl-) d. oxygen (O) e. sodium (Na+)

e. sodium (Na+)

isotope

one of several forms of a single element, the nuclei of which contain the same number of protons but different numbers of neutrons

radioactive

pertaining to an atom with an unstable nucleus that spontaneously breaks apart or decays, with the emission of radiation

hydrophilic

pertaining to molecules that dissolve readily in water, or to molecules that form hydrogen bonds with water; polar

hydrophobic

pertaining to molecules that do not dissolve in water or form hydrogen bonds with water; nonpolar

acidic

referring to a solution with an H+ concentration exceeding that of OH-;referring to a substance that releases H+

basic

referring to a solution with an H+ concentration less than that of OH-; referring to a substance that combines with H+

specific heat

the amount of energy required to raise the temperature of 1 gram of a substance by 1 degrees celcius

atomic nucleus

the central part of an atom that contains protons and neutrons

heat of vaporization

the energy that must be supplied to a compound to transform it from a liquid into a gas at its boiling temperature

capillary action

the movement of water within narrow spaces resulting from its properties of adhesion and cohesion

atomic number

the number of protons in the nuclei of all atoms of a particular element

dissolve

the process by which solvent molecules completely surround and disperse the individual atoms or molecules of another substance, the solute

surface tension

the property of a liquid to resist penetration by objects at its interface with the air, due to cohesion between molecules of the liquid

atom

the smallest unit of an element that retains the properties of the elements

adhesion

the tendency of polar molecules (such as water) to adhere to polar surfaces (such as glass)

cohesion

the tendency of the molecules of a substance to stick together

mass number

the total number of protons and neutrons in the nucleus of an atom

hydrogen bond

the weak attraction between a hydrogen atom that bears a partial positive charge (due to polar covalent bonding with another atom) and another atom (oxygen, nitrogen, or fluorine) that bears a partial negative charge; hydrogen bonds may form between atoms of a single molecule or of different molecules