Vocabulary about Chemistry

1. accuracy - Accuracy is a measure of how close a measured value is to its true value. For example, if an object is exactly a meter long and you measure it as 1.1 meters long, that is more accurate than if you measured it at 1.5 meters long.
2. acid - There are several ways to define an acid, but they include any chemical that gives off protons or H⁺ in water. Acids have a pH less than 7. They turn the pH indicator phenolphthalein colorless and turn litmus paper red.
3. acid anhydride - An acid anhydride is an oxide that forms an acid when it is reacted with water. For example, when SO₃^- is added to water, it becomes sulfuric acid, H₂SO₄.
4. actual yield - The actual yield is the amount of product you actually obtain from a chemical reaction, as in the amount you can measure or weigh as opposed to a calculated value.
5.addition reaction - An addition reaction is a chemical reaction in which atoms add to a carbon-carbon multiple bond.
6. alcohol - An alcohol is any organic molecule that has an -OH group.
7. aldehyde - An aldehyde is any organic molecule that has a -COH group.
8. alkali metal - An alkali metal is a metal in Group I of the periodic table. Examples of alkali metals include lithium, sodium, and potassium.
9. alkaline earth metal - An alkaline earth metal is an element belonging to Group II of the periodic table.
Examples of alkaline earth metals are magnesium and calcium
10. alkane - An alkane is an organic molecule that only contains single carbon-carbon bonds.
11. alkene - An alkene is an organic molecule that contains at least one C=C or carbon-carbon double bond.
12. alkyne - An alkyne is an organic molecule that contains at least one carbon-carbon triple bond.
13.allotrope - Allotropes are different forms of a phase of an element. For example, diamond and graphite are allotropes of carbon.
14. alpha particle - An alpha particle is another name for a helium nucleus, which contains two protons and two neutrons. It's called an alpha particle in reference to radioactive (alpha) decay.
15. amine - An amine is an organic molecule in which one or more of the hydrogen atoms in ammonia have been replaced by an organic group. An example of an amine is methylamine.
16. base - A base is a compound that produces OH^- ions or electrons in water or that accepts protons. An example of a common base is sodium hydroxide, NaOH.
17. beta particle - A beta particle is an electron, although the term is used when the electron is emitted in radioactive decay.
18. binary compound - A binary compound is one made up of two elements.
19. binding energy - Binding energy is the energy that holds protons and neutrons together in the atomic nucleus.
20. bond energy - Bond energy is the amount of energy required to break one mole of chemical bonds.
21. bond length - Bond length is the average distance between the nuclei of two atoms that share a bond.
22. buffer - A liquid that resists change in pH when an acid or base is added. A buffer consists of a weak acid and its conjugate base. An example of a buffer is acetic acid and sodium acetate.
23. calorimetry - Calorimetry is the study of heat flow. Calorimetry may be used to find the heat of reaction of two compounds or the heat of combustion of a compound, for example.
24. carboxylic acid - A carboxylic acid is an organic molecule containing a -COOH group. An example of a carboxylic acid is acetic acid.
25. catalyst - A catalyst is a substance that lowers the activation energy of a reaction or speeds it up without being consumed by the reaction.
Enzymes are proteins that act as catalysts for biochemical reactions.
26. cathode - A cathode is the electrode which gains electrons or is reduced. In other words, it is where reduction occurs in an electrochemical cell.
27. chemical equation - A chemical equation is a description of a chemical reaction, including what reacts, what is produced, and which direction(s) the reaction proceeds.
28. chemical property - A chemical property is a property that can only be observed when a chemical change occurs. Flammability is an example of a chemical property, since you can't measure how flammable a substance is without igniting it (making/breaking chemical bonds).
29. covalent bond - A covalent bond is a chemical bond formed when two atoms share two electrons.
30. critical mass - Critical mass is the minimum quantity of radioactive material needed to cause a nuclear chain reaction.
31. critical point - The critical point is the endpoint of the liquid-vapor line in a phase diagram, past which a supercritical liquid forms. At the critical point, the liquid and vapor phases become indistinguishable from one another.
32. crystal - A crystal is an ordered, repeating three-dimensional pattern of ions, atoms, or molecules. Most crystals are ionic solids, although other forms of crystals exist.
33. delocalization - Delocalization is when electrons become free to move all over a molecule, such as when double bonds occur on adjacent atoms in a molecule.
34. denature - There are two common meanings for this in chemistry. First, it can refer to any process used to make ethanol unfit for consumption (denatured alcohol). Second, denaturing can mean breaking down the three-dimensional structure of a molecule, such as a protein is denatured when exposed to heat.
35. diffusion - Diffusion is the movement of particles from an area of higher concentration to one of lower concentration.
36. dilution - Dilution is when a solvent is added to a solution, making it less concentrated.
37. dissociation - Dissociation is when a chemical reaction breaks a compound into twoor more parts.
For example, NaCl dissociates into Na⁺ and Cl^- in water.
38. double displacement reaction - A double displacement or double replacement reaction is when cations of two compounds switch places.
39. effusion - Effusion is when a gas moves through an opening into a low-pressure container (e.g., is drawn by a vacuum). Effusion occurs more quickly than diffusion because additional molecules aren't in the way.
40. electrolysis - Electrolysis is using electricity to break the bonds in a compound to break it apart.
41. electrolyte - An electrolyte is an ionic compound that dissolves in water to produce ions, which can conduct electricity. Strong electrolytes completely dissociate in water, while weak electrolytes only partially dissociate or break apart in water.
42. enthalpy - Enthalpy is a measure of the amount of energy in a system.
43. entropy - Entropy is a measure of the disorder or randomness in a system.
44. enzyme - An enzyme is a protein that acts as a catalyst in a biochemical reaction.
45. ester - An ester is an organic molecule with a R-CO-OR' function group.
46. Kelvin - Kelvin is a unit of temperature. A Kelvin is equal in size to a degree Celsius, although Kelvin starts from absolute zero. Add 273.15 to a Celsius temperature to get the Kelvin value. Kelvin is not reported with a ° symbol. For example, you would simply write 300K not 300°K.
47. ketone - A ketone is a molecule that contains a R-CO-R' functional group. An example of a common ketone is acetone (dimethyl ketone).
48. kinetic energy - Kinetic energy is energy of motion. The more an object moves, the more kinetic energy it has.
49. quantum theory - Quantum theory is the description of energy levels and the predictions about the behavior of atoms at specific energy levels.
50. radioactivity - Radioactivity occurs when the atomi nucleus is unstable and breaks apart, releasing energy or radiation.
51. synthesis - Synthesis is making a larger molecule from two or more atoms or smaller molecules.
52. system - A system includes everything you are evaluating in a situation.
53. temperature - Temperature is a measure of the average kinetic energy of particles.
54. thermodynamics - Thermodynamics is the study of energy.
55. titration - Titration is a procedure in which the concentration of an acid or base is determined by measuring how much base or acid is required to neutralize it.