chemical vocabulary

Chemical Vocabulary

NO	VOCAB	EXPLANATION
1	acid	This is anything that gives off H+ ions in water. Acids have a pH less than 7 and are good at dissolving metals. They turn litmus paper red andphenolphthalein colorless.
2	activity series	This is when you arrange elements in the order of how much they tend to react with water and acids.
3	alcohol: alcohol	An organic molecule containing an -OH group
4	anode	The electrode where oxidation occurs. In other words, this is where electrons are lost by a substance.
5	aqueous	dissolved in water
6	atomic mass unit (a.m.u.)	This is the smallest unit of mass we use in chemistry, and is equivalent to 1/12 the mass of carbon-12. To all intents and purposes, protons and neutrons weigh 1 a.m.u.
7	atomic radius	This is one half the distance between two bonded nuclei. Why don't we just measure the distance from the nucleus to the outside of the atom - after all, isn't that the same thing as a radius? It is, but atoms are also (theoretically) infinitely large (due to quantum mechanics), making this impossible to measure.
8	atomic solid:	A solid where there's a bunch of atoms in the lattice. This is different from an ionic solid, where ions are the things that are sticking together.
9	base	A compound that gives off OH- ions in water. They are slippery and bitter and have a pH greater than 7.
10	battery	This is when a bunch of voltaic cells are stuck together.
11	beta particle	A radioactive particle equivalent to an electron.
12	buffer	A liquid that resists change in pH by the addition of acid or base. It consists of a weak acid and it's conjugate base (acetic acid and sodium acetate, for example).
13	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.
14	catalyst	A substance that speeds up a chemical reaction without being used up by the reaction. Enzymes are catalysts because they allow the reactions that take place in the body to occur fast enough that we can live.
15	cathode	The electrode in which reduction occurs. Reduction is when a compound gains electrons.
16	colloid	It's a suspension.
17	diffusion	When particles move from areas of high concentration to areas of low concentration. For example, if you open a bottle of ammonia on one end of the room, the concentration of ammonia molecules in the air is very high on that side of the room. As a result, they tend to migrate across the room, which explains why you can smell it after a little while. Be careful not to mix this up with effusion (see definition).
18	dilution	When you add solvent to a solution to make it less concentrated.
19	dipole moment	When a molecule has some charge separation (usually because the molecule is polar), it's said to have a dipole moment.
20	double-displacement reaction (a.k.a. double replacement reaction):	When the cations of two ionic compounds switch places.
21	effusion	When a gas moves through an opening into a chamber that contains no pressure. Effusion is much faster than diffusion because there are  no other gas molecules to get in the way.
22	electrolysis	When electricity is used to break apart a chemical compound.
23	electrolyte	An ionic compound that dissolves in water to conduct electricity. Strong electrolytes break apart completely in water; weak electrolytes only fall apart a little bit.
24	ground state	The lowest energy state possible for an electron.
25	group	A column (the things up and down) in the periodic table. Elements in the same group tend to have the same properties. These are also called "families".
26	halogen	The elements in group 17. They're really reactive.
27	heat of reaction	The amount of heat absorbed or released in a reaction. Also called the "enthalpy of reaction"
28	indicator	A compound that turns different colors at different pH values. We generally like to have the color change at a pH of around seven because that's where the equivalence point of a titration is.
29	inhibitor	A substance that slows down a chemical reaction.
30	inorganic compound	Any compound that doesn't contain carbon (except for carbon dioxide, carbon monoxide, and carbonates).
31	insoluble	When something doesn't dissolve.
32	intermediate	A molecule which exists for a short time in a chemical reaction before turning into the product.
33	mass	The amount of matter in an object. The more mass, the more stuff is present.
34	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.
35	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.
36	molar mass	The mass of one mole of particles.
37	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.
38	molarity	A unit of concentration equal to moles of solute divided by liters of solution.
39	synthesis	When you make a big molecule from two or more smaller ones.
40	system	Everything you're talking about at the moment.
41	temperature	A measurement of the average kinetic energy of the particles in a system.