Bio 1200 Chapter 2

An atom's atomic number represents:

the number of protons

Matter is anything that has 1.______ and occupies 2. _______

1. Mass 2. Space

When two water molecules are near each other, a hydrogen bond will form between the more positive 1.______ and the more negative 2.______ atoms of neighboring water molecules.

1. Oxygen 2. Hydrogen

Click and drag on elements in order: 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. The solid state The gaseous state The liquid state

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

Chemical reactions require a source of energy and also may require a substance called a(n) 1.______ that speeds up the reaction rate. Most chemical reactions proceed toward a state called 2._________ , in which the rate of product formation equals the rate of reactant formation.

1. catalyst 2. equilibrium

pH is defined as the 1._______ logarithm to the base 10 of the 2.______ ion concentration.

1. negative 2. hydrogen (H+)

What happens to acidity as pH decreases?

Acidity increases More H+ ions

Why are atoms likely to share electrons?

Because they have unfilled outer valence shells.

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. Electrons move in different patterns depending on the number of atoms in the elements. Electrons move in very discrete, defined paths. Electrons all occupy the same orbital.

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

Which of the following are common features of chemical reactions? Select all that apply. Many chemical reactions that occur in cells require catalysts. Chemical reactions cease when they reach equilibrium. Many chemical reactions in living organisms take place in a watery environment. 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. Chemical reactions proceed toward equilibrium. Chemical reactions require a source of energy.

A(n) ______ bond is formed when two atoms of different electronegativities share electrons.

Polar covalent bond

Energy is defined as

The capacity to do work.

A Na+ ion forms when:

a sodium atom loses an electron

Electronegativity is the ability of an atom to:

attract electrons

what does water do in a Hydrolysis reaction:

break apart molecules via water

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

element

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.

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

ion

A covalent bond is one in which a pair of electrons:

is shared between two atoms

An atom or ion is most stable when:

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

Isotopes of the same element differ in their number of:

neutrons

Colligative properties depend on the ______ dissolved in a solution.

number of particles

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

product Reason: In the conversion of methane and oxygen to carbon dioxide and water, carbon dioxide is created.

Substances dissolved in liquid are known as:

solutes

Solutes dissolved in a solvent form a(n):

solution

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

solvent

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

The pH decreases

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

Lungs

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

Reactant Reason: In the conversion of methane and oxygen to carbon dioxide and water, oxygen reacts.

The hydrogen bonds between water molecules form between:

an oxygen atom on one water molecule and a hydrogen atom on a second water molecule Reason: A partially positive and partially negative atom pair is required for hydrogen bonds to form, hydrogen and oxygen can't be both.

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

buffer

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

colligative properties

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

concentration

Which state of water is the most dense?

liquid

To freeze water, energy is:

released

The amount of energy required to raise the temperature of 1 gram of a substance by 1 degree C.

specific heat

_____ is defined as the amount of heat energy required to raise the temperature of 1 gram of a substance by 1 degree C

specific heat capacity

Select all that apply Select all of the following that are true about atoms that have partially filled energy shells. tend to share, lose, or gain electrons have 8 electrons in the outermost shell are chemically inert can form compounds

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

Select all that apply When water freezes: the rate of hydrogen bond breakage slows water molecules are packed into a less dense formation the H2O molecules in ice are in a much more orderly arrangement than in the liquid state water loses its hydrophilic status and becomes more hydrophobic

the rate of hydrogen bond breakage slows water molecules are packed into a less dense formation the H2O molecules in ice are in a much more orderly arrangement than in the liquid state

Unpaired ______ electrons enable chemical bonds to form among atoms.

valence

Within an atom, 1.______ and neutrons have nearly equal masses, while 2.________ have a much smaller mass.

1. Protons 2. Electrons

In humans, water comprises approximately ______ of body weight.

60-70%

What occurs during all chemical reactions?

Chemical bonds are broken or formed.

Atoms tend to be most stable when their outer shells are 1._________ ; this can be accomplished by gaining, losing, or sharing 2. _________

1. filled 2. electrons

An atom's atomic number is based on the number of 1.______ it contains. In an atom that is not in a chemical reaction, the number of protons equals the number of 2._______ .

1. protons 2. electrons

A solution is composed of 1.______ dissolved in a(n) 2.______.

1. solutes 2. solvent

Which of the following is the best description of the modern model of atomic structure? A central nucleus surrounded by electrons traveling in clearly defined orbits A collection of positive and negative charges uniformly distributed throughout the atom A central nucleus surrounded by cloudlike orbitals containing electrons

A central nucleus surrounded by cloudlike orbitals containing electrons

Select all that apply Which of the following changes in the physical state of water require the input of energy? Changing from gas to liquid Changing from solid to liquid Changing from gas to solid Changing from liquid to solid Changing from liquid to gas

Changing from solid to liquid Changing from liquid to gas

Atoms are most stable when their outer shells are filled with:

Electrons

Select all that apply Compared with liquid water, ice has: greater hydrogen bonds between individual water molecules a more orderly arrangement of water molecules fewer hydrogen bonds between individual water molecules a less orderly arrangement of water molecules

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

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.

Select all that apply Which two particles are the primary determinants of an element's atomic mass? Protons Electrons Neutrons

Protons Neutrons

What is the heat of fusion of a substance?

The amount of heat energy released when 1 mole of the substance is converted from liquid to solid

Select all that apply Which of the following statements are true of a polar covalent bond? Electrons are transferred completely from one atom to the other. The atoms in the bond have the same electronegativity. The atoms in the bond differ in electronegativity. The two atoms in the bond share the electrons unequally. The electrons are closer to the nucleus of the atom with lower electronegativity. The shared electrons are equidistant between the nuclei of the two atoms.

The atoms in the bond differ in electronegativity. The two atoms in the bond share the electrons unequally.

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

The nonpolar region Reason: This region is hydrophilic. Thus, it will be at the surface of the micelle, where it is attracted to the surrounding water molecules.

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.

Select all that apply Which of the following properties are shared by many chemical reactions that occur in cells? They tend to proceed toward equilibrium. They are not reversible. They often require a catalyst. They require energy.

They tend to proceed toward equilibrium. They often require a catalyst. They require energy.

True or False Molecules with covalent bonds are flexible.

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

Living organisms minimize changes in their internal pH using compounds called:

buffers

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

pH

Pure water (H2O) can ionize into:

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