chemical vocabulary

CHEMICAL VOCABULARY

NO	VOCABULARY	EXPLANATION
1	acid dissociation constant (Ka)	This is equal to the ratio of the concentrations of an acid's conjugate base and the acid present when a weak acid dissociates in water. That is, if you have a solution of Acid X where the concentration of the conjugate base is 0.5 M and the concentration of the acid is 10 M, the acid dissociation constant is 0.5/10 = 0.05.
2	activation energy	The minimum amount of energy needed for a chemical reaction to take place. For some reactions this is very small (it onl takes a spark to make gasoline burn). For others, it's very high (when you burnmagnesium, you need to hold it over a Bunsen burner for a minute or so).
3	Avogadro's Law	If you've got two gases under the same conditions of temperature, pressure, and volume, they've got the same number of particles (atoms or molecules). This law only works for ideal gases, none of whichactually exist.
4	calorimetry	The study of heat flow. Usually you'd do calorimetry to find the heat of combustion of a compound or the heat of reaction of two compounds.
5	chromatography	This is when you use a system containing a mobile phase (usually a liquid in general chemistry classes) and a stationary phase (something dissolved in the liquid) to separate different compounds. This is usually done by exploiting the differing polarities of solutes, though you can do it a whole slew o' ways.
6	circuit	The closed path in a circuit through which electrons flow.
7	coagulation	When you destroy a colloid by letting the particles settle out.
8		decomposition: When a big molecule falls apart to make two or more little ones.
9	degenerate	Things (usually orbitals) are said to be degenerate if they have the same energy. This term is used a whole lot in quantum mechanics. Also when dealing with kids who steal cars.
10	delocalization	This is when electrons can move around all over a molecule. This happens when you have double bonds on adjacent atoms in a molecul(conjugated hydrocarbon)
11	endothermic	When a process absorbs energy (gets cold).
12	functional group	A generic term for a group of atoms that cause a molecule to react in a specific way. It's really common to talk about this in organic chemistry, where you have "aldehydes, carboxylic acids, amines" and so on.
13	gamma ray	High energy light given off during a nuclear process. When a nucleus gives off this light, it goes to a lower energy state, making it mor stable.
14	geometrical isomer:	isomerism where atoms or groups of atoms can take up  different positions around a double bond or a ring. This is also called cistrans-isomerism.
15	heterogeneous mixture	A mixture where the substances aren't equally distributed.
16	homogeneous mixture:	A mixture that looks really "smooth" because everything is mixed up really well.
17	irreversible reaction	A chemical reaction in which the reagents make products but the products can't reform reagents. Most chemical reactions in basic chemistry classes are thought of as being irreversible.
18	isotonic solutions	Solutions containing the same osmotic pressure
19	Lewis acid	An electron-pair acceptor (carbonyl groups are really good ones)
20	Lewis base:	An electron-pair donor. Things with lone pairs like water and ammonia are really good ones.
21	Lewis structure	A structural formula that shows all of the atoms and valenceelectrons in a molecule.
22	ligand	A molecule or ion that sticks to the central atom in a complex. Common examples are ammonia, carbon monoxide, or water.
23	limiting reagent	If you do a chemical reaction and one of the chemicals gets used up before the other one, the one that got used up is called the "limiting reagent" because it limited the amount of product that could be formed. The  other one is called the excess reagent.
24	line spectrum	A spectrum showing only certain wavelengths.
25	mechanism	A step-by-step sequence that shows how the products of a reaction are made from the reagents. Mechanisms are very frequently shown during organic chemistry.
26	molality	The number of moles of solute per kilogram of solvent in a solution. This is a unit of concentration that's not anywhere near as handy or common as molarity.
27	molar mass:	The mass of one mole of particles.
28	molar volume:	The volume of one mole of a substance at STP. If you believe that everything is an ideal gas, this is always 22.4 liters. Unfortunately,there's no such thing as an ideal gas.
29	molecular compound	A compound held together by covalent bonds.
30	molecular formula	A formula that shows the correct quantity of all of the atoms in a molecule.
31	monatomic ion	An ion that has only one atom, like the chloride ion.
32	optical isomerism	Isomerism in which the isomers cause plane polarized light to rotate in different directions.
33	orbital	This is where the electrons in an atom live.
34	organic compound	A compound that contains carbon (except carbondioxide, carbon monoxide, and carbonates)
35	osmosis	The flow of a pure liquid into an area of high concentration through a semi-permeable membrane
36	oxidation number	The apparent charge on an atom.
37	STP	See standard temperature and pressure.
38	unshared electron pair:	two electrons that aren't involved in chemical bonding. Also frequently referred to as a "lone pair".
39	unshared electron pair	two electrons that aren't involved in  chemical bonding. Also frequently referred to as a "lone pair".
40	valence electron	The outermost electrons in an atom.
41	synthesis	When you make a big molecule from two or more smaller ones.
42	system	Everything you're talking about at the moment.
43	temperture:	A measurement of the average kinetic energy of the particles in a system