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Humanities Libertexts

Key Terms

  • Page ID
    19151
  • acid
    compound that releases hydrogen ions (H+) in solution
    activation energy
    amount of energy greater than the energy contained in the reactants, which must be overcome for a reaction to proceed
    adenosine triphosphate (ATP)
    nucleotide containing ribose and an adenine base that is essential in energy transfer
    amino acid
    building block of proteins; characterized by an amino and carboxyl functional groups and a variable side-chain
    anion
    atom with a negative charge
    atom
    smallest unit of an element that retains the unique properties of that element
    atomic number
    number of protons in the nucleus of an atom
    base
    compound that accepts hydrogen ions (H+) in solution
    bond
    electrical force linking atoms
    buffer
    solution containing a weak acid or a weak base that opposes wide fluctuations in the pH of body fluids
    carbohydrate
    class of organic compounds built from sugars, molecules containing carbon, hydrogen, and oxygen in a 1-2-1 ratio
    catalyst
    substance that increases the rate of a chemical reaction without itself being changed in the process
    cation
    atom with a positive charge
    chemical energy
    form of energy that is absorbed as chemical bonds form, stored as they are maintained, and released as they are broken
    colloid
    liquid mixture in which the solute particles consist of clumps of molecules large enough to scatter light
    compound
    substance composed of two or more different elements joined by chemical bonds
    concentration
    number of particles within a given space
    covalent bond
    chemical bond in which two atoms share electrons, thereby completing their valence shells
    decomposition reaction
    type of catabolic reaction in which one or more bonds within a larger molecule are broken, resulting in the release of smaller molecules or atoms
    denaturation
    change in the structure of a molecule through physical or chemical means
    deoxyribonucleic acid (DNA)
    deoxyribose-containing nucleotide that stores genetic information
    disaccharide
    pair of carbohydrate monomers bonded by dehydration synthesis via a glycosidic bond
    disulfide bond
    covalent bond formed within a polypeptide between sulfide groups of sulfur-containing amino acids, for example, cysteine
    electron
    subatomic particle having a negative charge and nearly no mass; found orbiting the atom’s nucleus
    electron shell
    area of space a given distance from an atom’s nucleus in which electrons are grouped
    element
    substance that cannot be created or broken down by ordinary chemical means
    enzyme
    protein or RNA that catalyzes chemical reactions
    exchange reaction
    type of chemical reaction in which bonds are both formed and broken, resulting in the transfer of components
    functional group
    group of atoms linked by strong covalent bonds that tends to behave as a distinct unit in chemical reactions with other atoms
    hydrogen bond
    dipole-dipole bond in which a hydrogen atom covalently bonded to an electronegative atom is weakly attracted to a second electronegative atom
    inorganic compound
    substance that does not contain both carbon and hydrogen
    ion
    atom with an overall positive or negative charge
    ionic bond
    attraction between an anion and a cation
    isotope
    one of the variations of an element in which the number of neutrons differ from each other
    kinetic energy
    energy that matter possesses because of its motion
    lipid
    class of nonpolar organic compounds built from hydrocarbons and distinguished by the fact that they are not soluble in water
    macromolecule
    large molecule formed by covalent bonding
    mass number
    sum of the number of protons and neutrons in the nucleus of an atom
    matter
    physical substance; that which occupies space and has mass
    molecule
    two or more atoms covalently bonded together
    monosaccharide
    monomer of carbohydrate; also known as a simple sugar
    neutron
    heavy subatomic particle having no electrical charge and found in the atom’s nucleus
    nucleotide
    class of organic compounds composed of one or more phosphate groups, a pentose sugar, and a base
    organic compound
    substance that contains both carbon and hydrogen
    peptide bond
    covalent bond formed by dehydration synthesis between two amino acids
    periodic table of the elements
    arrangement of the elements in a table according to their atomic number; elements having similar properties because of their electron arrangements compose columns in the table, while elements having the same number of valence shells compose rows in the table
    pH
    negative logarithm of the hydrogen ion (H+) concentration of a solution
    phospholipid
    a lipid compound in which a phosphate group is combined with a diglyceride
    phosphorylation
    addition of one or more phosphate groups to an organic compound
    polar molecule
    molecule with regions that have opposite charges resulting from uneven numbers of electrons in the nuclei of the atoms participating in the covalent bond
    polysaccharide
    compound consisting of more than two carbohydrate monomers bonded by dehydration synthesis via glycosidic bonds
    potential energy
    stored energy matter possesses because of the positioning or structure of its components
    product
    one or more substances produced by a chemical reaction
    prostaglandin
    lipid compound derived from fatty acid chains and important in regulating several body processes
    protein
    class of organic compounds that are composed of many amino acids linked together by peptide bonds
    proton
    heavy subatomic particle having a positive charge and found in the atom’s nucleus
    purine
    nitrogen-containing base with a double ring structure; adenine and guanine
    pyrimidine
    nitrogen-containing base with a single ring structure; cytosine, thiamine, and uracil
    radioactive isotope
    unstable, heavy isotope that gives off subatomic particles, or electromagnetic energy, as it decays; also called radioisotopes
    reactant
    one or more substances that enter into the reaction
    ribonucleic acid (RNA)
    ribose-containing nucleotide that helps manifest the genetic code as protein
    solution
    homogeneous liquid mixture in which a solute is dissolved into molecules within a solvent
    steroid
    (also, sterol) lipid compound composed of four hydrocarbon rings bonded to a variety of other atoms and molecules
    substrate
    reactant in an enzymatic reaction
    suspension
    liquid mixture in which particles distributed in the liquid settle out over time
    synthesis reaction
    type of anabolic reaction in which two or more atoms or molecules bond, resulting in the formation of a larger molecule
    triglyceride
    lipid compound composed of a glycerol molecule bonded with three fatty acid chains
    valence shell
    outermost electron shell of an atom
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