Chemistry Vocabulary

1. Acid - An acid is a compound with a pH of less than 7 that forms hydrogen ions when  dissolved in water. Acids react when coming into contact with bases and some metals to form salts.
2. Atom - The atom is a basic unit of matter and the smallest unit of an element. It consists of a nucleus which is surrounded by a cloud of electrons.
3.   Acid rain-rainwater with an acidic pH, a result of air pollution by sulfur dioxide and nitrogen oxides.
4. Acidic oxide-a covalent oxide that dissolves in water to give an acidic solution.
5.  Base - A base is a substance with a pH higher than seven. Bases are defined as donating a pair of valence electrons.
6. Bond - An attraction between atoms that forms chemical substances
7. Bond energy  - the energy required to break a given chemical bond.
8. Bond length - the distance between the nuclei of the two atoms that are connected by a bond.
9. Carbon cycle - A method by which carbon is constantly moved throughout the biosphere.
10. Chemical equilibrium a dynamic reaction system in which the concentrations of all reactants and products remain constant as a function of time.
11. Chemical formula a representation of a molecule in which the symbols for the elements are used to indicate the types of atoms present and subscripts are used to show the relative numbers of atoms.
12. Chemical kinetics the area of chemistry that concerns reaction rates.
13. Chemical property the ability of a substance to change to a different substance.
14. Chemical reaction - A process where a set of substances undergo a chemical change to form a different substance.
15. Compound - A chemical compound is a pure substance made up of two or more elements.
16. Density - Density is the mass per unit volume of a substance.
17. Distillation - The process of separating mixtures by boiling a liquid and then recovering the cooled gas.
18. Electron - A particle of an atom that orbits the atom's nucleus and carries a negative charge.
19. Element - A pure chemical substance that is made up of one type of atom. Each atom in an element is defined by an atomic number which is the number of protons in the nucleus.
20. Ion - An atom or molecule which has a negative or positive charge because the number of electrons does not equal the number of protons.
21. Ionic bond - Ionic bonding is when an electron is traded between atoms in order to have full outer shells.
22. Isotopes - Isotopes are atoms from the same element that have different numbers of neutrons.
23. Malleable - A substance is said to be malleable if it can be pounded into a thin sheet.
24. Metal - A substance that is a good conductor of heat and electricity. They are generally malleable, ductile, and shiny.
25. Mixture - A combination of two or more substances that are not chemically combined.
26. Molecule - A molecule is formed when two or more atoms are joined
27. together by a chemical bond.
28. Neutron - A particle in the nucleus of an atom that has no electric charge.
29. Noble gases - A family of elements that makes up column 18 of the periodic table. They are very stable due to their full outer electron shells.
30. Nucleus - The central core of an atom containing the protons and neutrons.
31. Oxidation - The name for the process when oxygen combines with another element to form a compound.
32. Periodic table - A table of the chemical elements arranged by atomic number.
33. PH scale - The pH measures the activity of the hydrogen ion in substances. If a substance has a pH less than 7 it is said to be acidic. If its pH is greater than 7 then it said to be basic or alkaline.
34. Proton - A particle within the nucleus of an atom that holds a positive charge.
35. Reaction - The process that occurs when two or more chemical substances  are combined to form another chemical substance.
36. Salts - Salts are chemical compounds that are formed by the reaction of  an acid and a base.
37. Solution - A homogeneous mixture where one substance called the solute is fully dissolved into another substance called the solvent. For example, a solution is formed when salt dissolves into water to make the  solution salt water.
38. Valence electron - An electron in an atom that can participate in a chemical bond.
39. Weak acid-an acid that dissociates only to a slight extent in aqueous solution.
40. Weak base-a base that reacts with water to produce hydroxide ions to only a slight extent in aqueous solution.