Exam 1 Review:  Chapter 2 - Properties of Molecules

molecule - A substance formed by the chemical combination (chemical bonding, usually covalent or ionic bonding) of two or more atoms (of the same or different elements); the smallest particle of a chemical compound that retains the chemical properties of the compound.  [A stable molecule occurs when the total energy of the combination has a lower energy state than the separated atoms.]

compound - A substance formed by the chemical combination (chemical bonding, usually covalent or ionic bonding) of two or more atoms of different elements.  [A stable compound occurs when the total energy of the combination has a lower energy state than the separated atoms.]

inorganic compound - Any example of the large series of  molecules which do not contain carbon atoms (other than a few exceptions such as carbon monoxide, carbon dioxide, and carbides); biologically important examples of inorganic compounds include water, acids, bases, salts, and electrolytes.

organic compound - Any example of the large series of biological molecules which always contain carbon, almost always contain both hydrogen and oxygen, and sometimes contain other elements such as nitrogen, sulfur, phosphorus; biologically important examples of organic compounds include carbohydrates, lipids, proteins, and nucleic acids.

chemical energy - The usable power (energy*) liberated by a chemical reaction when chemical bonds are broken or the usable power (energy*)  absorbed in the formation of a chemical compound when new chemical bonds are made.  See also chemical energy in the universe.  [*Energy is the capacity to do work within a given system.]

chemical bond - Any of the several forces or mechanisms, primarily relationships between electrons, by which atoms or ions are bound in a molecule or crystal; examples include the covalent bond, ionic bond, hydrogen bond, hydrophobic bond = van der Waals attraction and metallic* bond.  (*The chemical bond characteristic of metals, in which mobile valence electrons are shared among atoms in a usually stable crystalline structure).  [A stable compound occurs when the total energy of the combination has a lower energy state than the separated atoms.]

covalent bond - A strong attraction between atoms because they are sharing one or more outer shell valence electrons; much chemical energy is required to create this sharing and much energy will be released if it is broken; it is the strongest of the four types of chemical bonds.

polar covalent bond - One of two types of covalent bonds, a covalent bond in which the sharing of the electron pair is unequal, with the electrons spending more time around the more nonmetallic (electronegative) atom; in such a bond relationship there is a charge separation with one atom being slightly more positive and the other more negative; a classic example of polar covalent bonds are found in the bonds of the water molecule in which the oxygen atom is more electronegative than the hydrogens.

ionic bond - A variable strength attraction between atoms in which one or more outer shell valence electrons from one atom are removed and attached to another atom, resulting in positive and negative ions which attract each other; chemical energy is required to achieve this transfer and energy will be released if it is reversed; it is the second strongest of the four types of chemical bonds.

ions = electrolytes - A substance which carries an electrochemical charge because its structure has unequal numbers of electrons and protons.

cation - An ion or group of ions having a positive charge and, characteristically, attracting and having the potential to make ionic bonds with negatively charged anions; such positively charged ions move toward the negative electrode in electrolysis and electrophoresis.

anion - An ion or group of ions having a negative charge and, characteristically, attracting and having the potential to make ionic bonds with positively charged cations; such negatively charged ions move toward the positive electrode in electrolysis and electrophoresis.

hydrogen bond -  A weak (only ~5% of the strength of a covalent bond) electrostatic attraction (positive to negative) between atoms in which a hydrogen atom of one polar molecule (most often a water molecule) is attracted to an electronegative atom, especially a nitrogen, oxygen, or fluorine atom, usually of another* polar molecule of the same or a different polar substance.  [*Note:  Large molecules may have hydrogen bonds between atoms within the same molecule.]

Hydrogen Bonding Between Two Water Molecules	Hydrogen Bonding Between Two Atoms in the same Large Molecule

List:

 2. four types of chemical bonds.

     covalent bond - ionic bond - hydrogen bond - van der Waals attraction (hydrophobic bond)

 4. four categories of organic compounds which are macromolecules and list the monomer(s) used in building each type of polymer.

 

Category of Organic Macromolecules	Monomer(s) Used in Each Type of Polymer
carbohydrate = polysaccharide	simple sugars = monosaccharides
lipid	fatty acids + glycerol + certain other polar molecules (sometimes)
protein	amino acids
nucleic acids	pentose sugars + nitrogenous bases + phosphate ions

 5. three specific examples of each of the above four categories or classes of biological macromolecules (list particular molecules, not categories of molecules).

11. three chemical elements found in carbohydrates, lipids, proteins, and nucleic acids.

              carbon (C), Hydrogen (H), and oxygen (O)

12. a chemical elements found in proteins, and nucleic acids but not in carbohydrates and lipids.

              in proteins:  sulfur (S)

              in nucleic acids:  phosphorus (P)

              in both proteins and nucleic acids:  nitrogen (N)