BIO1010 - Chapter 2: Review Questions

Oxygen has eight electrons. How many valence electrons does it have?

6

In humans, water comprises approximately ______ of body weight.

60-70%

True or false: Matter exists in only one of two states: solid or liquid.

False

Which component of humans has the greatest per cent of water?

Lungs Reason: The blood has about 80% water, while the lungs have nearly 90%!

Pure water can ionize into which of the following?

Positively charged protons (H+) and negatively charged hydroxide (OH-) ions

What does the atomic number of an atom represent?

the number of protons

The chemical formula of glucose is C6H12O6. How many oxygen atoms are in one molecule of glucose? Include just the number in your answer.

6

Nitrogen contains seven protons, seven neutrons, and seven electrons. Nitrogen has an atomic number of _____.

7

Oxygen contains eight protons, eight electrons, and eight neutrons. What is its atomic number?

8

pH is defined as the _____ _____ to the base 10 of the _____ ion concentration.

Blank 1: negative or - Blank 2: logarithm or log Blank 3: H+, hydrogen, H, hydronium, proton, [H+], h positive, H positive, or H plus

True or false: Molecules that contain covalent bonds are rigid, inflexible structures.

False

True or false: An element is made up of two or more types of atoms.

False. Reason: An element is composed of only one kind of atom.

Which ions are produced when water ionizes?

H+, OH-

What four elements are the most common in living organisms?

HONC - hydrogen, oxygen, nitrogen, carbon

What part of an amphipathic molecule would be oriented toward the center of a micelle?

The nonpolar region

In which of these conditions would an atom or ion be most stable?

When its outermost shell is occupied by its full complement of electrons

What are the concentrations of H+ and OH- ions in pure water?

[OH-] = 10-7 M [H+] = 10-7 M

Compared with liquid water, ice has ______.

a more orderly arrangement of water molecules greater hydrogen bonds between individual water molecules

A substance that releases hydrogen ions into solution is called a(n) _____

acid

Electronegativity is the ability of an atom to ______.

attract electrons

A substance that absorbs hydrogen ions in solution is called a(n) ______.

base

Hydrolysis reactions ______.

break apart molecules via water

What type of compound minimizes pH fluctuations in the fluids of living organisms?

buffer Reason: Water is the solvent in which most biochemical reactions occur. Water has a neutral pH, but its pH can easily change with the addition of solutes. Reason: A base absorbs hydrogen ions from solution and causes pH to increase.

Living organisms minimize changes in their internal pH using compounds called ______.

buffers

The amount of solute (in grams) dissolved in a given volume of solution is the solution's ______.

concentration

Atoms share a pair of electrons when they form a(n) _____ bond.

covalent, nonpolar covalent

Hydrochloric acid is considered an acid because it releases _____ ions into solution.

hydrogen

When two water molecules are near each other, a hydrogen bond will form between the more positive _____ and the more negative _____ atoms of neighboring water molecules.

hydrogen, oxygen

In a(n) _____ reaction, water is used to break apart another molecule.

hydrolysis

Within an atom's structure, electrons can be found ______.

in cloudlike orbitals Reason: Electrons are found in orbitals, but they are cloudlike, not discrete, clearly defined structures.

An atom that has gained or lost electrons, and thus has a net electric charge, is called a(n) _____.

ion

An atom with a net electric charge is called a(n) ______.

ion

When a cation binds to an anion, a(n) _____ bond forms.

ionic

The region within an atom that surrounds the nucleus and in which there is a high probability of finding an electron is called an electron _____.

orbital

In a water molecule (H2O), the _____ atom has a partial negative charge, and the _____ atom has a partial positive charge.

oxygen, hydrogen

The hydrogen bonds connecting water molecules form between a(n) ______ atom on one molecule and a(n) ______ atom on another molecule.

oxygen, hydrogen Reason: A partially positive and partially negative atom pair is required for hydrogen bonds to form, hydrogen can't be both.

By mass, the most abundant element in living organisms is ______.

oxygen. Reason: The total number of hydrogen atoms in the human body is greater than the total number of oxygen atoms. However, by mass, oxygen is more abundant. Hydrogen makes up 9% of human body mass, and oxygen makes up 65%. By mass, oxygen is the most abundant element in the human body.

The ______ of a solution is the negative base 10 logarithm of the H+ concentration of the solution.

pH

Elements are electrically neutral because there are equal numbers of ______ in a given atom.

protons electrons Reason: Protons are positively charged, and neutrons are uncharged. The nucleus, which contains protons and neutrons, has a net positive charge. The presence of equal numbers of protons and negatively charged electrons gives an atom a net neutral charge.

Atoms are electrically neutral because they have equal numbers of ______ and ______.

protons, electrons

Within an atom, _____ and neutrons have nearly equal masses, while _____ have a much smaller mass.

protons, electrons

In living organisms, the three states of matter are:

solid, liquid, and gas.

The concentration of a liquid is defined as the amount of ______ dissolved in a unit volume of solution.

solute

Substances dissolved in liquid are called ______.

solutes

A liquid that can dissolve substances is known as a(n) _____.

solvent

Put the physical states of water in order based on the intermolecular distances between water molecules. The TOP position should be the state in which the molecules are the farthest apart.

1. the gaseous state 2. the solid state 3. the liquid state

In pure water, the concentrations of H+ and OH- ions are ______.

10-7 M each

Explain the difference between an electron shell and an orbital.

An electron shell is a region outside the nucleus of an atom occupied by electrons of a given energy level. More than one orbital can be found within an electron shell. An orbital may be spherical or dumbbell-shaped and contains up to two electrons.

What occurs during all chemical reactions?

Chemical bonds are broken or formed.

Which of the following are common features of chemical reactions?

Chemical reactions proceed toward equilibrium. Chemical reactions require a source of energy. Many chemical reactions that occur in cells require catalysts. Many chemical reactions in living organisms take place in a watery environment.

Which of the following statements are true of a nonpolar covalent bond?

Electrons are shared equally between the two atoms. The two atoms have similar electronegativity values.

Carbon has six electrons. How many valence electrons does it have?

Four. Reason: Carbon has a total of 6 electrons. Two are in the first electron shell, and the remaining 4 are in the valence shell.

Molecules are likely to dissolve easily in water if they contain what type of bonds?

Ionic bonds Polar covalent bonds

Which of the following molecules are predicted to easily dissolve in water?

Ions that carry full electric charges Carbohydrates that contain -OH groups

Which two particles are the primary determinants of an element's atomic mass?

Neutrons, protons

Phosphorus exists in several isotopes, including 31P and 32P. These are expected to have different ______.

Number of neutrons. Reason: Isotopes differ in the number of neutrons they contain.

A base will release _____ ions when dissolved in water.

OH, hydroxyl, OH-, hydroxide, or negative

There are ____ type(s) of atoms that can be found in a single element.

One

Which of the following are considered subatomic particles?

Protons, neutrons, and electrons.

What are the three subatomic particles?

Protons, neutrons, electrons

What does the atomic number of an atom represent?

The number of protons. Reason: Protons plus neutrons contribute to atomic mass, not atomic number.

When oil dissolves in a soapy solution, where is the oil found?

The oil will be in the centers of the soap micelles.

In a micelle, which portion of the amphipathic molecules are oriented toward the surface of the sphere?

The polar region Reason: This region is hydrophobic and so must be oriented towards the interior of the micelle to minimize interactions with water molecules.

Which of the following statements is true of a polar covalent bond?

The shared electrons are closer to one nucleus than to the other. Reason: In a polar covalent bond, electrons are shared unequally between the two atoms in the bond. Reason: In a polar covalent bond, the two atoms have different electronegativity values. Reason: When one or more electrons is transferred from one atom to another, an ionic bond, not a polar covalent bond, may form.

Molecules with covalent bonds ______.

are flexible within certain limits Reason: Covalent bonds are flexible. Molecules can rotate around covalent bonds. Molecules that have covalent bonds have flexible three-dimensional shapes.

The _____ of an atom is a measure of its ability to attract electrons when in a bond with another atom.

electronegativity

An atom or ion is most stable when its outermost shell is occupied by its full complement of

electrons

What type of bond occurs when a cation binds to an anion?

ionic bond

A covalent bond is one in which a pair of electrons ______.

is shared between two atoms

Isotopes of an element differ from one another in the number of _____ they contain.

neutrons

Each hydrogen atom in a water molecule has a partial _____ charge, whereas the oxygen atom has a partial _____ charge.

positive, negative

An atom's atomic number is based on the number of _____ it contains. In an atom that is not in a chemical reaction, this number equals to the number of _____.

protons, electrons