BIOLOGY 2E CHAPTER 2 THE CHEMICAL FOUNDATION OF LIFE

acid

Molecule that donates hydrogen ions and increases the concentration of hydrogen ions in a solution.

adhesion

Attraction between water molecules and other molecules.

aliphatic hydrocarbon

Hydrocarbon consisting of a linear chain of carbon atoms.

anion

Negative ion that is formed by an atom gaining one or more electrons.

aromatic hydrocarbon

Hydrocarbon consisting of closed rings of carbon atoms.

atom

The smallest unit of matter that retains all of the chemical properties of an element.

atomic mass

Calculated mean of the mass number for an element’s isotopes.

atomic number

Total number of protons in an atom.

balanced chemical equation

Statement of a chemical reaction with the number of each type of atom equalized for both the products and reactants.

base

Molecule that donates hydroxide ions or otherwise binds excess hydrogen ions and decreases the hydrogen ions' concentration in a solution.

buffer

Substance that resists a change in pH by absorbing or releasing hydrogen or hydroxide ions.

calorie

Amount of heat required to change the temperature of one gram of water by one degree Celsius.

capillary action

Occurs because water molecules are attracted to charges on the inner surfaces of narrow tubular structures such as glass tubes, drawing the water molecules to the tubes' sides.

cation

Positive ion that is formed by an atom losing one or more electrons.

chemical bond

Interaction between two or more of the same or different atoms that results in forming molecules.

chemical reaction

Process leading to rearranging atoms in molecules.

chemical reactivity

The ability to combine and to chemically bond with each other.

cohesion

Intermolecular forces between water molecules caused by the polar nature of water; responsible for surface tension.

compound

Substance composed of molecules consisting of atoms of at least two different elements.

covalent bond

Type of strong bond formed between two atoms of the same or different elements; forms when electrons are shared between atoms.

dissociation

Release of an ion from a molecule such that the original molecule now consists of an ion and the charged remains of the original.

electrolyte

Ion necessary for nerve impulse conduction, muscle contractions, and water balance.

electron

Negatively charged subatomic particle that resides outside of the nucleus in the electron orbital.

electron configuration

Arrangement of electrons in an atom’s electron shell.

electron orbital

How electrons are spatially distributed surrounding the nucleus; the area where we are most likely to find an electron.

electron transfer

Movement of electrons from one element to another; important in creating ionic bonds.

electronegativity

Ability of some elements to attract electrons, acquiring partial negative charges in molecules.

element

One of 118 unique substances that cannot break down into smaller substances.

enantiomers

Molecules that differ in how the atoms are three dimensionally placed such that they are mirror images of each other.

equilibrium

Steady state of relative reactant and product concentration in reversible chemical reactions in a closed system.

evaporation

Change from liquid to gaseous state at a body of water's surface, plant leaves, or an organism's skin.

functional group

Group of atoms that provides a specific function to a carbon skeleton.

geometric isomer

Isomer with similar bonding patterns differing in the placement of atoms alongside a double covalent bond.

heat of vaporization of water

High amount of energy required for liquid water to turn into water vapor.

hydrocarbon

Molecule that consists only of carbon and hydrogen.

hydrogen bond

Weak bond between slightly positively charged hydrogen atoms and slightly negatively charged atoms in other molecules.

hydrophilic

Describes ions or polar molecules that interact well with other polar molecules such as water.

hydrophobic

Describes uncharged nonpolar molecules that do not interact well with polar molecules such as water.

inert gas

Element with filled outer electron shell that is unreactive with other atoms.

ion

Atom or chemical group that does not contain equal numbers of protons and electrons.

ionic bond

Chemical bond that forms between ions with opposite charges.

irreversible chemical reaction

Chemical reaction where reactants proceed unidirectionally to form products.

isomers

Molecules that differ from one another even though they share the same chemical formula.

isotope

One or more forms of an element that have different numbers of neutrons.

law of mass action

Chemical law stating that the rate of a reaction is proportional to the concentration of the reacting substances.

litmus paper

Filter paper treated with a natural water-soluble dye that changes its color as the pH of the environment changes.

mass number

Total number of protons and neutrons in an atom.

matter

Anything that has mass and occupies space.

molecule

Two or more atoms chemically bonded together.

neutron

Uncharged particle that resides in an atom's nucleus.

noble gas

See inert gas.

nonpolar covalent bond

Type of covalent bond that forms between atoms when electrons are shared equally between them.

nucleus

Core of an atom; contains protons and neutrons.

octet rule

Rule that atoms are most stable when they hold eight electrons in their outermost shells.

orbital

Region surrounding the nucleus; contains electron(s).

organic molecule

Any molecule containing carbon (except carbon dioxide).

periodic table

Organizational chart of elements indicating each element's atomic number and atomic mass.

pH paper

See litmus paper.

pH scale

Scale ranging from zero to 14 that is inversely proportional to the hydrogen ions' concentration in a solution.

polar covalent bond

Type of covalent bond that forms as a result of unequal electron sharing.

product

Molecule that is a result of a chemical reaction.

proton

Positively charged particle that resides in the atom's nucleus.

radioisotope

Isotope that emits radiation to form more stable elements.

reactant

Molecule that takes part in a chemical reaction.

reversible chemical reaction

Chemical reaction that functions bidirectionally.

solvent

Substance capable of dissolving another substance.

specific heat capacity

The amount of heat one gram of a substance must absorb or lose to change its temperature by one degree Celsius.

sphere of hydration

When a polar water molecule surrounds charged or polar molecules thus keeping them dissolved.

structural isomers

Molecules that share a chemical formula but differ in the placement of their chemical bonds.

substituted hydrocarbon

Hydrocarbon containing an atom of another element in place of one of the backbone carbons.

surface tension

Tension at the surface of a body of liquid that prevents the molecules from separating.

valence shell

Outermost shell of an atom.

van der Waals interaction

Very weak interaction between molecules due to temporary charges.