Biology 1: Chapter 2
Bases can ________.
both take up hydrogen ions and release hydroxide ions
A covalent bond involves the sharing of
In order to form covalent bonds each atom must contribute an equal number of electrons so, electrons are shared in pairs.
Why do cells need buffering agents?
to minimize the changes in pH of their internal environment
An atom's valence electron shell
determines its chemical reactivity.
An atom with a neutral charge has
equal numbers of protons and electrons.
Which one of the following is the smallest unit of matter that has all the properties of an element?
atom
The type of bond that would form from the transfer of an electron from one atom to another, as depicted in the figure, is a
ionic
Some insects can stride on the surface of water because water
has surface tension.
The atomic structure of water satisfies the octet rule by
having oxygen share electrons with two hydrogen atoms.
Which of the following is a property of acids?
release hydrogen ions when dissolved in a liquid
The number of neutrons in the nucleus of an average atom of an element is best estimated by
subtracting the number of protons from the mass number.
An atom that has an electrical charge is called a(n)
Ion
Which of the following is not a way in which chemical bonds can be formed?
splitting electrons
Isotopes of an atom differ in their
atomic mass.
An ionic bond forms when
ions form when an atom gives away or takes in an electron but the actual bond does not form until the charged atoms ate attracted to one another.
Which of the following is not one of the most common elements in living things?
iron
Which of the following would not be a valuable use for radioactive isotopes?
damaging DNA of healthy cells
A water molecule, as shown here, is polar because of ________.
unequal sharing of electrons
Cola has a pH of 3.5. This means that it has an excess of ________ ions and would be called a(n) ________.
H+; acid
What is the steam being given off when water boils?
Hydrogen bonds link water molecules together. As they absorb heat the bonds begin to break causing water to enter into gaseous state and evaporate into the environment.
The particles that are found in the nucleus of an atom are the
neutrons and protons
The atomic structure of water satisfies the octet rule by having
oxygen share electrons with two hydrogen atoms.
Elements differ from each other in their ________.
physical properties and atomic number
You are caring for the freshwater aquarium of a friend while they are on vacation. You are told to check the pH of the tank and make sure that it stays between 6.5 and 7.0. When you check the water the pH is 8.0. The water in the tank is
tenfold change
Which of the following describe how an acid disrupts the chemical bonds of molecules in a cell?
the H+ ions can disrupt hydrogen bonds as the slightly negative portion of the molecule is more attracted to it than to the hydrogen that was part of the bond.
Which of the following is NOT a compound?
O2
The pH of pure water is ______ because ___________________________.
7.0; water dissociates an equal number of H+ ions and OH-
An element has an atomic number of 78. The number of protons and electrons in a neutral atom of the element are
78 protons and 78 electrons.
A strong acid has less H+ in solution.
A strong acid dissociates nearly completely in water. A weak acid dissociates only partially. Since a strong acid dissociates nearly completely, the concentration of hydrogen (H+) is said to have a higher acidity.
Which of the following is not a contributing event in the formation of acid rain?
Fossil fuels consume oxygen removing it from the atmosphere.
All atoms of the same element have the same
atomic number
Glucose, C6H12O6, is best described as a(n)
compound
Which of these does not occur when a sodium atom transfers an electron to a chlorine atom?
Ionic bonds are formed when two atoms are held together by an attraction between ions. Sodium transfers a negatively charged electron over to chlorine. The result is sodium having a positive charge (Na+) and chlorine now having a negative charge (Cl-). These ions have an attraction that creates the ionic bond that holds them together.
Which of the following explains the events occurring when water boils?
The hydrogen atoms break away from the oxygen and escape as vapor.
Regarding atoms, identify which statement below is correct.
The number and arrangement of electrons in an atom governs its chemical activity.
What do lemons, tomatoes, and coffee all have in common chemically?
They all produce H+ ions in solution, making them acids.
In what ways are radioactive isotopes potentially harmful?
Unmonitored release into the environment can make changes in a cell's DNA
Of the following examples, which best demonstrates the property of water cohesion?
Water can move up a 100-foot pine tree, from the roots to the leaves.
Baking soda is sometimes used as an antacid. The chemical name for baking soda is sodium bicarbonate. What is the bicarbonate doing to help with stomach upset?
It is serving as a buffer to take up excess H+ ions from stomach acid.
Which of the following would be an example of the value of water's heat capacity?
Living organisms are better able to maintain their internal body temperature because the temperature of their environment changes very slowly.
Which property of water would help to account for how an individual who is exercising and producing excessive heat can maintain a constant body temperature?
Water has high heat capacity.
The pH scale is a mathematical indicator of the
concentration of H+ present in a solution.
The pH scale is a mathematical indicator of ________.
the concentration of H+ present in a solution
Chemical bonds involve
the giving, taking or sharing of electrons.
