Chemical Bonds: bonds formed by unpaired "electrons" of one “atom” interacting with those of another. “Energy” is stored when bonds are formed. Energy is released when bonds are broken. (Norman, 6/11/09)

There are three types of strong chemical bonds - “covalent bonds,”  “hydrogen bonds,” and “ionic bonds.” (Hunt, 200) The linkage of atoms with other atoms serves as the basis for life, and also gives life its great diversity. Two or more atoms bonded together make up a “molecule.” (Brooker, 27)

Covalent Bond(s): a process in which atoms share a pair of electrons. Covalent bonds are strong chemical bonds, because the shared electrons behave as if they belong to each atom. (Brooker, 27) In covalent bonds, electrons from the outer shell of two atoms are shared with each other, in order to complete the outer shells of both atoms. (Brooker, 28) Can be characterized as “polar covalent bonds” and “non-polar covalent  bonds.” (Norman, 6/11/09)

Disulfide Bond: sulfur to sulfur bond. (Lewis, 331) A ‘bridge’ or covalent bond which links two "amino acid side chains" together. (Brooker, 54)

Double Bond: a bond that occurs when the atoms of a molecule share two pairs of electrons. (Brooker, G-11) Two covalent bonds between two atoms as in "oxygen,"  'alkenes' and 'ketones. With two electron pairs involved in the bondng, there is a region of high electron density between the two atoms joined by a double bond. (Hunt, 117)

Non-Polar Covalent Bond: bond in which electrons are shared equally between atoms. (Norton Lectures, 6/11/09)

Peptide Bond: bond that joins amino acids. (Lewis, 190) The covalent bond formed between a “carboxyl group” and an “amino group.” When many “amino acids” are joined by peptide bonds, the resulting molecule is called a “polypeptide.” (Brooker, 50) The formation of a peptide bond is an example of a “condensation reaction.” (Hunt, 266)

Polar Covalent Bond: covalent bonds formed between atoms of different elements so that the shared electrons are drawn towards the more electronegative atom. One end of the bond has a slight excess of negative charge. The other end of the bond has a slight deficit of electrons so that the ‘charge cloud’ of electrons does not cancel the positive charge on the nucleus. Molecules with polar bonds are generally more reactive than non-polar molecules. (Hunt, 281) Unequal ‘sharing’ of electrons. 'Loose' connection. Includes "hydrogen" bonds which are chemical bonds between hydrogen and an electronegative element or elements. (Norton Lectures, 6/11/09) The distribution of electrons around the atoms creates a “polarity” across the “molecule.” (Brooker 28)

Hydrogen Bond: a type of attraction between molecules which is much stronger than other types of intermolecular force, but much weaker than covalent bonding. (Hunt, 184) A slightly positively charged hydrogen ion of one water molecule is attracted to the slightly negatively charged oxygen ion of a nearby molecule. Each water molecule can form hydrogen bonds with a maximum of four neighbors. The attraction of water molecules for one another is also described as “hydrophilic.” Hydrogen bonding gives water some interesting properties, such as high surface tension (small insects can walk across water), strong cohesion (water droplets cling together), and a high boiling point. Water can also break down, or dissolve, salts. (Kolb, 89-90)

Ionic Bond(s): formation of a chemical bond following a transfer of electrons between two ions with opposite charges. (NCIt) Bond formed when a “cation” binds with an “anion.” (Norman, 6/11/09)