bio 110 chapter 2

molecules closest to farthest apart

-solid state -liquid state -gaseous

In humans, water comprises approximately Blank______ of body weight.

60-70%

Why are atoms likely to share electrons

Because they have unfilled outer valence shells.

Which of the following changes in the physical state of water require the input of energy?

Changing from liquid to gas Changing from solid to liquid

Why does ice float in liquid water?

Ice is less dense than liquid water.

High specific heat, surface tension, and cohesion are several properties of water involving

hydrogen bonds

Colligative properties depend on the _____ dissolved in a solution.

number of particles

What are the three subatomic particles?

protons, neutrons, electrons

The following statements are about atoms that have partially filled energy shells. Identify the ones that are true.

- they can form compounds -they tend to share, lose, or gain electrons

Chemical reactions require a source of energy and also may require a substance called a(n)_________that speeds up the reaction rate. Most chemical reactions proceed toward a state called_________in which the rate of product formation equals the rate of reactant formation.

-catalyst equilibrium

Atoms tend to be most stable when their outer shells are ___________; this can be accomplished by gaining, losing, or sharing________

-filled -electrons

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.

-oxygen -hydrogen

The atomic number of an element is equal to the number of ______it contains. Its atomic mass includes the number of protons and the number of ______

-protons -neutrons

Which of the following properties are shared by many chemical reactions that occur in cells?

-they tend to proceed toward equilibruim -they often require a catalyst -they require enegry

In a single element,__________ type(s) of atoms can be found.

1

The most common type of carbon atom has six protons, six electrons, and six neutrons. What is its atomic mass?

12 daltons and 12 amu

Here are three descriptions of the modern model of atomic structure. Which is the best?

A central nucleus surrounded by cloudlike orbitals containing electrons

Polar covalent O-H bonds in water molecules enable hydrogen bonds to form between water molecules. Which of the following properties of water result from hydrogen bond formation?

Adhesion Surface tension High specific heat High heat of vaporization Cohesion

What occurs during all chemical reactions?

Chemical bonds are broken or formed.

Which of the following are common features of chemical reactions?

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

Which of the following best describes a contemporary model of electron movement within atoms?

Electrons move in orbitals, although their exact location cannot be precisely predicted in these orbitals.

Which ions are produced when water ionizes?

H+ and OH-

Which of the following are functions of water in animals?

Serve as lubricant during feeding Flush out wastes Dissolve chemicals and nutrients

What is a likely predictor of how many covalent bonds an atom can form?

The electron configuration in the outermost shell

Compared with liquid water, ice has Blank______.

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

Which of the following solutions contains the highest concentration of protons?

a solution with pH 2.0

If you add H+ ions to a solution, it becomes more Blank______.

acidic

A solution of pH 5 is said to be ____________ because it contains more ________________

acidic; H+ ions than OH- ions

A solution in which water is the solvent is called a(n) _________ solution.

aqueous solution

Molecules with covalent bonds

are flexible within certain limits

Electronegativity is the ability of an atom to Blank______.

attract electrons

ionic bond

bond between a cation and an anion

hydrogen bond

bond between atoms with partial positive and partial negative charges

non polar covalent bond

bond in which two atoms share electrons equally

polar covalent bond

bond in which two atoms share electrons unequally

Hydrolysis reactions

break apart molecules via water

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

buffer

Living organisms minimize changes in their internal pH using compounds called

buffers

Energy is defined as

capacity to do work

Which of the following is an element?

carbon

What occurs during all chemical reactions?

chemical bonds are broken or formed

The ______ force of water molecules aids in the movement of fluids through the vessels of plants.

cohesive

Properties of a solution that depend strictly on the total number of dissolved solutes, and not the specific type of solute, are called ________ properties.

colligative

Properties of a solution that depend strictly on the total number of dissolved solutes, and not the specific type of solute, are called_______ properties.

colligative

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

concentration

Which subatomic particle is found in the space that surrounds the nucleus?

electron

Within atoms, electrons are organized by energy levels called

electron shell

Orbitals are found in Blank______ or energy levels.

electron shells

Atoms are most stable when their outer shells are filled with

electrons

A pure substance made up of only one atom is called a(n)

element

When the rate of the forward reaction is equal to the rate of the reverse reaction, chemical _______has been reached.

equilibrium

In a chemical reaction, if there is no longer a change in the concentration of reactants and products, then Blank______.

equilibrium has been reached

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

false

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

false

When water is heated, the rate at which _____ bonds break increases, and water molecules are converted to the ________ state.

hydrogen gaseous

Which types of chemical bonds are easily broken in water?

hydrogen bonds ionic bonds

Water is used to break apart another molecule in a(n)

hydrolysis reactions

Within an atom's structure, electrons can be found

in cloudlike orbitals

Electronegativity differences between atoms dictate the polarity of molecules by ______.

influencing whether covalent bonds are polar or nonpolar

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

ions

Which element plays an essential role in the transport of oxygen in vertebrates?

iron

A covalent bond is one in which a pair of electrons

is shared between two atoms

Which component of humans has the greatest percent of water?

lungs

Matter is anything that has ______and occupies______ .

mass and occupies space

An element's atomic Blank______ is based on the protons and neutrons it contains, while an element's atomic Blank______ is based only on the number of protons.

mass, number

The sum of the atomic masses of all atoms in a molecule is equal to the molecule's ___________mass.

molecular

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

negative logarithm H+

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

neutrons

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

numbers of neutrons

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

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

orbitals

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

pH

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

polar region

Pure water can ionize into which of the following?

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

In the conversion of methane and oxygen to carbon dioxide and water, carbon dioxide is a(n) Blank______.

product

What type of subatomic particle occurs in each different element in a unique number and is therefore used to identify specific elements?

proton

Atoms of different chemical elements can be differentiated based on the number of

protons in the nucleus

Atoms contain three types of particles: positively charged_____ , negatively charged _______, and uncharged __________.

protons, electrons, neutrons

A typical atom consists of three main subatomic particles:_______ ,_______ , and _______ .

protons, neutrons, and electrons

Consider the reaction: CH4 + 2 O2 ⇌ CO2 + 2 H2O. Oxygen serves as a(n)

reactant

To freeze water, energy is Blank______.

release

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

solute

Substances dissolved in liquid are called Blank______.

solutes

A solution is composed of ______ dissolved in a ______.

solutes; solvent

Solutes dissolved in a solvent form a

solution

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

solvent

______ is the amount of energy required to raise the temperature of 1 gram of a substance by 1o C.

specific heat

The molecular mass of a molecule is equal to the Blank______ in the molecule.

sum of the atomic masses of all atoms

heat of vaporization

the heat energy required to convert 1 mole of a substance from liquid to gas

specific heat

the heat energy required to raise the temperature of 1 gram of a substance by 1 degree Celsius

heat capacity

the heat energy required to raise the temperature of an entire object

heat of fusion

the heat energy that must be withdrawn or released from a substance to convert it from liquid to solid

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

the non polar region

Valence electrons are found in Blank______.

the outermost energy shell

What happens to the pH of a solution when H+ ions are added to it?

the pH decreases

which of the following scenarios are atoms the most stable

their outer shells are filled with electrons

Elements that are present in extremely low quantities yet are essential for growth and function of living organisms are termed

trace elements

Chemical bonds can form among atoms due to the presence of unpaired _____________electrons

valence

Electrons in an atom's outermost energy shells are called _____electrons.

valence

An aqueous solution is one in which the solvent is Blank______.

water