Chapter 2 Flashcards
which is anything that occupies space and has mass.
Matter
is the amount of matter in an object
Mass
is the gravitational force acting on an object of a given mass. For example, the weight of an apple results from the force of gravity “pulling” on the apple’s mass.
weight
of an element is equal to the number of protons in each atom and, because the number of electrons is equal to the number of protons, the atomic number is also the number of electrons.
atomic number
has no electrical charge
neutron
has one positive charge
proton
has one negative charge
electron
of an element is the number of protons plus the number of neutrons in each atom. For example, the mass number for carbon is 12 because it has 6 protons and 6 neutrons.
mass number
are two or more forms of the same element that have the same number of protons and electrons but a different number of neutrons. Thus, isotopes have the same atomic number but different mass numbers.
Isotopes
of an element is the average mass of its naturally occurring isotopes, taking into account the relative abundance of each isotope. For example, the atomic mass of the element carbon is 12.01 Da
atomic mass
1 mole (abbreviated mol). Stated another way, a mole of a substance contains Avogadro’s number of entities, such as atoms, ions, or molecules.
Avogadro’s number
The mass of 1 mole of a substance expressed in grams, is a convenient way to determine the number of atoms in a sample of an element.
molar mass
When this occurs, the numbers of protons and electrons are no longer equal, and a charged particle
ion
Positively charged ions
cations
negatively charged ions
anions
forms when electrons are transferred between atoms, creating oppositely charged ions. For example, Na+ and Cl− are held together by ionic bonding to form an array of ions called sodium chloride (NaCl), or table salt (figure 2.5b,c).
ionic bond
forms when atoms share one or more pairs of electrons. The sharing of electrons, rather than transfer of electrons, occurs because the atoms have similar electronegativities.
covalent bond
The sharing of one pair of electrons by two atoms, A single line between the symbols of the atoms involved (e.g., H—H) represents a single covalent bond
single covalent bond
results when two atoms share 4 electrons, 2 from each atom. When a carbon atom combines with two oxygen atoms to form carbon dioxide (CO2), two double covalent bonds form. Double covalent bonds are indicated by a double line between the atoms (O=C=O).
double covalent bond
When electrons are shared equally between atoms, as in a hydrogen molecule
nonpolar covalent bonds
However, atoms bound to one another by a covalent bond do not always share their electrons equally because in these situations the electronegativity of one atom is stronger than the electronegativity of the other atom.
polar covalent bonds
is composed of two or more atoms chemically combined to form a structure that behaves as an independent unit. Sometimes the atoms that combine are of the same type, such as two hydrogen atoms combining to form a hydrogen molecule.
molecule
is a substance resulting from the chemical combination of two or more different types of atoms. Water is a molecule that is also a compound because it is a combination of two different atoms, hydrogen and oxygen.
compound
of a molecule or compound can be determined by adding up the atomic masses of its atoms (or ions). The term molecular mass is used for convenience for ionic compounds, even though they are not molecules.
molecular mass
If the positively charged hydrogen of one molecule is attracted to the negatively charged oxygen, nitrogen, or fluorine of another molecule
hydrogen bond
is the ability of one substance to dissolve in another—for example, sugar dissolving in water. Charged substances, such as sodium chloride, and polar substances, such as glucose, readily dissolve in water, whereas nonpolar substances, such as oils, do not.
Solubility
or separate, from one another because cations are attracted to the negative ends of water molecules and anions are attracted to the positive ends of water molecules.
dissociate
Cations and anions that dissociate in water, because they have the capacity to conduct an electric current, which is the flow of charged particles.
electrolytes
Molecules that do not dissociate form solutions that do not conduct electricity, Pure water is a nonelectrolyte.
nonelectrolytes
is when two or more reactants chemically combine to form a new and larger product.
synthesis reaction
is the reverse of a synthesis reaction—a larger reactant is chemically broken down into two or more smaller products.
decomposition reaction
the reaction can run in the opposite direction, so that the products are converted back to the original reactants.
reversible reaction
When the rate of product formation is equal to the rate of the reverse reaction, At equilibrium, the amount of reactants relative to the amount of products remains constant.
equilibrium
The loss of an electron by an atom
oxidation
the gain of an electron
reduction
Because one atom partially or completely loses an electron and another atom gains that electron, these reactions
oxidation-reduction reactions
results from the position or movement of objects. Many of the activities of the human body, such as moving a limb, breathing, and circulating blood, involve mechanical energy.
Mechanical energy
is a form of potential energy stored within the chemical bonds of a substance. In any chemical reaction, the potential energy in the chemical bonds of the reactants can be compared with the potential energy in the chemical bonds of the products.
Chemical energy
are substances that increase the rate of chemical reactions without being permanently changed or depleted themselves.
Catalysts
which are discussed in greater detail later in the chapter, are proteins that act as catalysts. Enzymes increase the rate of chemical reactions by lowering the activation energy necessary for the reaction to begin
Enzymes
generally deals with substances that do not contain carbon, although a more rigorous definition is the lack of carbon-hydrogen bonds
Inorganic chemistry
is the study of carbon-containing substances, with a few exceptions. For example, carbon monoxide (CO), carbon dioxide (CO2), and bicarbonate ions (HCO3−) are several important inorganic substances that contain carbon but lack C—H bonds.
Organic chemistry
is the attraction of water to another water molecule. Examples of cohesion are the surface tension exhibited when water bulges over the top of a full glass without spilling over and when beads of water form on the skin
Cohesion
is the same attractive force of hydrogen bonds of water that will also attract other molecules. An example of adhesion is the surface tension that draws water across a glass plate and holds a bead of water to the skin before it falls to the ground.
Adhesion
is a combination of two or more substances physically blended together, but not chemically combined.
mixture
is any mixture in which the substances are uniformly distributed. Solutions can be liquid, gas, or solid.
solution
Solutions are often described in terms of one substance dissolving in another
solute
solvent
is defined as a proton donor. A hydrogen ion (H+) is a proton because it results when an electron is lost from a hydrogen atom, which leaves just the proton nucleus.
acid
is defined as a proton acceptor. Any substance that binds to (accepts) H+ is a base. Many bases function as proton acceptors by releasing hydroxide ions (OH−) when they dissociate.
base
results if blood pH drops below 7.35, in which case the nervous system becomes depressed and the individual may become disoriented and possibly comatose
Acidosis
results if blood pH rises above 7.45. Then the nervous system becomes overexcitable, and the individual may become extremely nervous or have convulsions
Alkalosis
are the weak electrostatic attractions that exist between oppositely charged parts of molecules, or between ions and molecules. There is no exchange of electrons in intermolecular forces.
Intermolecular forces
is an especially important molecule for storing and providing energy in all living organisms. It consists of adenosine (the sugar ribose with the nitrogenous base adenine) and three phosphate groups
Adenosine triphosphate (ă-den′ō-sēn trImages-fos′fāt; ATP
