Modified Mastering (Biology 1100: Chapters 1-4)
Which of these relationships is true of an uncharged atom?
The number of protons is equal to the number of electrons.
Which of the following statements correctly describes any chemical reaction that has reached equilibrium?
The rates of the forward and reverse reactions are equal.
structural isomers
The two molecules shown in the figures are best described as ________.
Which statement is true of the energy levels of electrons in shells?
The valence shell has higher energy than other occupied shells.
Which of these refers to atoms with the same atomic number but different atomic masses?
These atoms are isotopes.
Because organisms are made primarily of water, they resist rapid temperature changes. This useful quality is based on water's __________.
high specific heat
Compared with 31P31P, the radioactive isotope 32P32P has...?
one more neutron.
A salamander relies on hydrogen bonding to stick to various surfaces. Therefore, a salamander would have the greatest difficulty clinging to a ________.
surface of hydrocarbons
In the term trace element, the adjective trace means that...?
the element is required in very small amounts.
Dr. Jones says an atom has 3 electrons in the first shell and four electrons in the second shell. Someone should tell Dr. Jones that ...
the first shell shouldn't have 3 electrons.
What determines the types of chemical reactions that an atom participates in?
the number of electrons in the outermost electron shell
Two atoms always represent the same element if they have ...
the same number of protons.
Which of the following is a hydrophobic material?
wax
Citric acid makes lemons taste sour. Which of the following is a functional group that would cause a molecule such as citric acid to be acidic?
carboxyl
The atoms of different phosphorus isotopes _____.
have different numbers of neutrons
Most organic compounds contain which atoms?
carbon, hydrogen, oxygen, nitrogen
The mass number of an atom is 15, and its atomic number is 7. The atom probably has...
8 neutrons in the nucleus.
Which of the following atoms has the smallest number of neutrons?
nitrogen-14
Polar attractions are ...
(a), (b), and (c) are correct: (a) forces between atoms with partial charges. (b) weaker than covalent bonds. (c) important because they are numerous.
Which statement is true of water's tensile strength?
(a), (b), and (c): (a) It results from hydrogen bonding. (b) It helps to pull water through plants.(c) It involves both cohesion and adhesion.
Identify all correct statements about the ionization of water.
- Dissociation of water produces equal numbers of OH- and H+. - Dissociation of water is reversible. - Water ionizes to form hydroxide and hydronium ions.
Several emergent properties of water contribute to the suitability of the environment for life. How does the ability of water to function as a versatile solvent arise from the structure of water molecules?
- Water molecules form hydrogen bonds with atoms that are part of polar covalent bonds in other molecules. - Water's versatility as a solvent arises from the polar covalent bonds of water molecules. - The partially charged regions of water molecules are attracted to oppositely charged ions.
Fluorine's atomic number is 9 and its atomic mass is 19. How many neutrons does fluorine have?
10
An atom has 8 protons, 8 neutrons, and 8 electrons. Another isotope of the same element might have ...
10 neutrons.
Measurements show that the pHpH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?
10^-4M
Measurements show that the pHpH of a particular lake is 4.0. What is the hydroxide ion concentration of the lake?
10^−10M
The innermost electron shell of an atom can hold up to _____ electrons.
2
How many electrons are present in a H- and H+ ion respectively?
2,0
An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many protons does boron have?
5
How many electrons participate in a triple covalent bond?
6
What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons?
6
We can represent atoms by listing the number of protons, neutrons, and electrons−−for example, 2p+,2n0,2e−2p+,2n0,2e− for helium. Which of the following represents the 18 O 18 O isotope of oxygen?
8p+,10n^0,8e−8p+,10n^0,8e−
Which of the following helps most to explain why water has a high specific heat?
A water molecule can make 4 hydrogen bonds.
double covalent
A(n) _____ bond joins these two oxygen atoms.
- More heat is required to raise the temperature of 1 g of water 1 ∘C than to raise the temperature of 1 g of ethyl alcohol 1 ∘C. - Water has a high specific heat due to the hydrogen bonding between water molecules. - Sulfuric acid is less resistant to temperature change than water.
Based on the information in the table, which of the following statements are true?
Which statement helps to explain why ice is less dense than liquid water?
Both (a) and (b): (a) Water molecules make hydrogen bonds at definite angles. (b) Cold molecules move less than warm molecules.
Water is a source of ______________ for chemical reactions in cells.
Both (a) and (b): (a) hydrogen atoms (b) oxygen atoms
Which factor is important in making it possible to cool yourself by sweating? Think carefully!
Both (a) and (b): (a) Molecules collide with varied angles and speeds. (b) Hydrogen bonds are relatively weak.
Visualize the structural formula of each of the following hydrocarbons. Which hydrocarbon has a double bond in its carbon skeleton?
C2H4
Which of the following is a hydrocarbon?
C3H8
An atom has 6 electrons, 6 protons, and 6 neutrons. You can tell that this atom belongs to the element _____ because _____________________.
C; it has 6 protons.
Variation in carbon chains is an important source of molecular complexity. How can carbon skeletons vary?
Carbon skeletons can vary in length, exhibit different branching structures, contain double bonds at different positions, and contain rings of carbon atoms
structural isomers
Choose the term that correctly describes the relationship between these two sugar molecules.
Which statement is true of atoms?
Electrons determine the atom's size.
Which statement about isomers is correct?
Enantiomers differ in biological activity.
Because carbon has a valence of 4, it can form four covalent bonds with other atoms. Such versatility of carbon allows for building the skeletons of organic molecules, including important biomolecules. For example, carbon skeletons in the shape of four fused rings make up steroids, some of which are sex hormones. Estradiol, a female sex hormone, and testosterone, a male sex hormone, are very similar in structure, differing only in two chemical groups. It leads to different shapes and chemical characteristics, allowing them to bind to molecules on the surface of different target cells and result in different effects, such as the differences between the lions in the photo.
How does the chemical structure of the carbon atom account for the differences between the male and female lions seen in the photo?
5
How many atoms in the pictured molecule can form hydrogen bonds with water molecules?
10
In the molecule below, how many atoms could make hydrogen bonds with water?
polar covalent
In this molecule, what type of bond is found between the oxygen and hydrogens?
Which of the following statements is true for water in its liquid state?
It has a heat of vaporization higher than most other substances.
Which of the following is true of oxygen that has 8 protons, 8 neutrons, and 8 electrons?
It has an atomic number of 8.
The H+ concentration of lemon juice is higher than the H+ concentration of household bleach by a factor of 10^11 (100 billion).
Look at the figure showing the pH values of some familiar aqueous solutions. What is the difference between H+ concentration in an acidic solution such as lemon juice (pH 2) and a basic solution such as household bleach (pH 13)?
Which of the following is a trace element found in the human body?
Magnesium
A(n) _____ refers to two or more atoms held together by covalent bonds.
Molecule
Which statement must be mentioned in explaining why amphipathic molecules line up at a water surface?
Polar groups attract one another.
Why doesn't oil mix with water?
Polar molecules attract one another.
Which model most accurately represents the current view of the structure of the atom?
Probability model
hydrogen
The brackets are indicating a(n) _____ bond.
4
This atom can form up to _____ single covalent bond(s).
Which of the following bonds can form between atoms of equal electronegativity?
Van der Waals interactions can form between atoms of equal electronegativity.
Covalent
What type of bond is joining the two hydrogen atoms?
single (nonpolar) covalent
What type of bond joins the carbon atom to each of the hydrogen atoms?
carboxyl
Which functional group is present in this molecule?
F
Which of functional groups listed below behaves as an acid?
A
Which of the functional groups behaves as a base?
The amino group is most likely to gain a proton.
Which of the functional groups shown above is most likely to gain a proton and become positively charged?
D
Which of these functional groups is a characteristic of alcohol?
E
Which of these groups is characteristic of thiols?
B
Which of these groups plays a major role in energy transfer?
C
Which of these is a carbonyl group?
F
Which of these is a carboxyl group?
D
Which of these is a hydroxyl group?
B
Which of these is a phosphate group?
A
Which one of these is an amino group?
All of the Above: - The atom is in the excited state. - An electron will move from the outer to the inner shell. - The atom has more than one valence electron.
Which statement is true of the atom shown in the diagram?
Surface tension.
Why isn't this insect drowning?
Dissolving is best described as ...?
a mingling of molecules and/or ions.
Which property of water allows a paper towel to pick up a puddle of water?
adhesion of water molecules to other kinds of molecules
Radioactive decay is likely to occur when ...
an atom has too many neutrons.
An ionic bond involves _____.
an attraction between ions of opposite charge
The open spaces in water's crystal structure make it possible for ...
aquatic life to exist at the North Pole.
Many of water's emergent properties, such as its cohesion, high specific heat, and high heat of vaporization, result from the fact that water molecules __________.
are attracted to each other by partial negative and positive charges on the oxygen and hydrogen atoms, respectively
Atoms with the same number of protons but with different electrical charges _____.
are different ions
About 25 of the 92 natural elements are known to be essential to life. Four of these 25 elements make up approximately 96% of living matter. Which of the following elements account for most of the remaining 4% of an organism's mass?
calcium, potassium, phosphorus, sulfur
Hydrogen bonds ...
can form between H and N.
The large diversity of shapes of biological molecules is possible because of the extensive presence of __________ in the molecules.
carbon
The tendency of an atom to pull electrons toward itself is referred to as its _____.
electronegativity
Van der Waals interactions may result under which of the following conditions?
electrons are not symmetrically distributed in a molecule
What process exerts the pull on water molecules that is relayed from leaf to root via cohesion?
evaporation
A water molecule can bond to up to _____ other water molecules by ____ bonds.
four ... hydrogen
What name is given to the bond between water molecules?
hydrogen
Water molecules have a polarity, which allows them to be electrically attracted to other water molecules and other polar molecules by weak chemical bonds known as _____.
hydrogen bonds
Which of the following types of bond is broken when water evaporates?
hydrogen bonds
Water has surface tension because ...
hydrogen bonds between surface water molecules resist being stretched.
In salt, what is the nature of the bond between sodium and chlorine?
ionic
The amount of energy that must be absorbed or lost to raise or lower the temperature of 1gram of liquid water by 1°C __________.
is 1 calorie
Though you add heat, the temperature of boiling water remains constant because ...?
it takes energy to break hydrogen bonds.
To find out the number of neutrons in an atom, we need to know the following.
mass and atomic number
The unequal sharing of electrons within a water molecule makes the water molecule _____.
polar
Which of the following subatomic particles always has a positive charge?
proton
Chemists assign atoms to chemical elements by counting their ________.
protons
An ion with six protons, seven neutrons, and a charge of 2+ has an atomic number of ________.
six