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