Chemical Vocabulary

50 CHEMICAL VOCABULARY
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 and phenolphthalein colorless.
Acid anhydride	This is an oxide that forms an acid when you stick it in water. An example is SO3- when you add water it turns into sulfuric acid, H2SO4.
Activation Energy	The minimum amount of energy needed for a chemical reaction to take place. For some reactions this is very small (it only takes a spark to make gasoline burn). For others, it's very high (when you burn magnesium, you need to hold it over a Bunsen burner for a minute or so).
Adsorption	When one substance collects of the surface of another one.
Alcohol	An organic molecule containing an -OH group
Aldehyde	An organic molecule containing a -COH group
Alkali Metals	Group I in the periodic table.
Alkali Earth Metals	Group II in the periodic table.
Akane	An organic molecule which contains only single carbon-carbon bonds
Alkene	An organic molecule containing at least one C=C bond
Amine	An organic molecule which consists of an ammonia molecule where one or more of the hydrogen atoms has been replaced by organic groups
Amino Acid	The basic building blocks of proteins. They're called "amino acids" because they're both amines (they contain nitrogen) and acids (carboxylic acids, to be precise)
Amphiprotic	When something is both an acid and a base. Like amino acids, for example.
Anode	The electrode where oxidation occurs. In other words, this is where electrons are lost by a substance.
Aqueous	Dissolved in water
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.
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.
Aufbau Principle	When you add protons to the nucleus to build up the elements, electrons are added into orbitals.
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 which actually exist.
Base Anhydride	An oxide that forms a base when water is added. CaO is an example, turning into calcium hydroxide in water.
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
Carboxylic Acid	An organic molecule with a -COOH group on it. Acetic acid is the most famous one.
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.
Cathode	The electrode in which reduction occurs. Reduction is when a compound gains electrons.
Chirality	When a molecule has a non superimposable mirror image. To imagine this, put your hands together. Although they are mirror images, you can't put them right on top of each other so they are interchangeable. Well, normal people can't, anyway.
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.
Concentration	A measurement of the amount of stuff (solute) dissolved in a liquid (solvent). The most common concentration unit is molarity (M), which is equal to the number of moles of solute divided by the number of liters of solution.
Condensation	When a vapor reforms a liquid. This is what happens on your bathroom mirror when you take a shower.
Conductance	A measurement of how well electricity can flow through an object.
Conjugate Acid	The compound formed when a base gains a proton (hydrogen atom).
Conjugate Base	The compound formed when an acid loses a proton (hydrogen atom).
Covalent Bond	A chemical bond formed when two atoms share two electrons.
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. Asa 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)
Dilution	When you add solvent to a solution to make it less concentrated.
Electron Affinity	The energy change that accompanies the addition of an electron to an atom in the gas phase.
Electro Negativity	A measurement of how much an atom tends to steal electrons from atoms that it's bonded to. Elements at the top right of the periodic table (excluding the noble gases) are very electronegative while atoms in the bottom left are not very electronegative (a.k.a. "electropositive")
Electropositive	When something is not at all electronegative. In fact, it tends to lose electrons rather than to gain them. Elements that are electropositive are generally to the left and bottom of the periodic table.
Empirical Formula	A reduced molecular formula.If you have a molecular formula and you can reduce all of the subscripts by some constant number,the result is the empirical formula.
Energy Level	A possible level of energy that an electron can have in an atom.
Exothermic	When a process gives off energy (gets hot).
Endothermic	When a process absorbs energy (gets cold).
Enthalpy	A measurement of the energy content of a system.
Entropy	A measurement of the randomness in a system.
Enzyme	A biological molecule that catalyzes reactions in living creatures.
Half-Life	The time required for half of the radioactive atoms in a sample to decay. When talking about chemical reactions, it's the amount of time required to make half the reagent react.
Half-Reaction	The oxidation or reduction part of a redox reaction.
Halogen	The elements in group 7. They're really reactive
Heterogeneous Mixture	A mixture where the substances aren't equally distributed.
Homogeneous Mixture	A mixture that looks really "smooth" because everything is mixed up really well.