H 1 Hydrogen 1.00794 | Periodic Table | He 2 Helium 4.002602 | |||||||||||||||

Li 3 Lithium 6.941 | Be 4 Beryllium 9.012182 | of the Elements | B 5 Boron 10.811 | C 6 Carbon 12.0107 | N 7 Nitrogen 14.0067 | O 8 Oxygen 15.9994 | F 9 Fluorine 18.9984032 | Ne 10 Neon 20.1797 | |||||||||

Na 11 Sodium 22.98976... | Mg 12 Magnesium 24.305 | mouse/touch for more information | Al 13 Aluminum 26.9815386 | Si 14 Silicon 28.0855 | P 15 Phosphorus 30.973762 | S 16 Sulfur 32.065 | Cl 17 Chlorine 35.453 | Ar 18 Argon 39.948 | |||||||||

K 19 Potassium 39.948 | Ca 20 Calcium 40.078 | Sc 21 Scandium 44.955912 | Ti 22 Titanium 47.867 | V 23 Vanadium 50.9415 | Cr 24 Chromium 51.9961 | Mn 25 Manganese 54.938045 | Fe 26 Iron 55.845 | Co 27 Cobalt 58.933195 | Ni 28 Nickel 58.6934 | Cu 29 Copper 63.546 | Zn 30 Zinc 65.38 | Ga 31 Gallium 69.723 | Ge 32 Germanium 72.63 | As 33 Arsenic 74.9216 | Se 34 Selenium 78.96 | Br 35 Bromine 79.904 | Kr 36 Krypton 83.798 |

Rb 37 Rubidium 85.4678 | Sr 38 Strontium 87.62 | Y 39 Yttrium 88.90585 | Zr 40 Zirconium 91.224 | Nb 41 Niobium 92.90628 | Mo 42 Molybdenum 95.96 | Tc 43 Technetium (98) | Ru 44 Ruthenium 101.07 | Rh 45 Rhodium 102.9055 | Pd 46 Palladium 106.42 | Ag 47 Silver 107.8682 | Cd 48 Cadmium 112.411 | In 49 Indium 114.818 | Sn 50 Tin 118.71 | Sb 51 Antimony 121.76 | Te 52 Tellurium 127.6 | I 53 Iodine 126.90447 | Xe 54 Xenon 131.293 |

Cs 55 Caesium 132.9054 | Ba 56 Barium 132.9054 | Hf 72 Hafnium 178.49 | Ta 73 Tantalum 180.94788 | W 74 Tungsten 183.84 | Re 75 Rhenium 186.207 | Os 76 Osmium 190.23 | Ir 77 Iridium 192.217 | Pt 78 Platinum 195.084 | Au 79 Gold 196.966569 | Hg 80 Mercury 200.59 | Ti 81 Thallium 204.3833 | Pb 82 Lead 207.2 | Bi 83 Bismuth 208.9804 | Po 84 Polonium (209) | At 85 Astatine (210) | Rn 86 Radon (222) | |

Fr 87 Francium (223) | Ra 88 Radium (226) | Rf 104 Rutherfordium (267) | Db 105 Dubnium (268) | Sg 106 Seaborgium (271) | Bh 107 Bohrium (272) | Hs 108 Hassium (270) | Mt 109 Meitnerium (276) | Ds 110 Darmstadium (281) | Rg 111 Roentgenium (280) | Cn 112 Copernicium (285) | Uut 113 Unutrium (284) | Uuq 114 Flerovium (289) | UuP 115 Ununpentium (288) | Lv 116 Livermorium (293) | Uus 117 Ununseptium (294) | Uuo 118 Ununoctium (294) | |

La 57 Lanthanum 138.90547 | Ce 58 Cerium 140.116 | Pr 59 Praseodymium 140.90765 | Nd 60 Neodymium 144.242 | Pm 61 Promethium (145) | Sm 62 Samarium 150.36 | Eu 63 Europium 151.964 | Gd 64 Gadolinium 157.25 | Tb 65 Terbium 158.92535 | Dy 66 Dysprosium 162.5 | Ho 67 Holmium 164.93032 | Er 68 Erbium 167.259 | Tm 69 Thulium 168.93421 | Yb 70 Ytterbium 173.054 | Lu 71 Lutetium 174.9668 | |||

Ac 89 Actinium (227) | Th 90 Thorium 232.03806 | Pa 91 Protactinium 231.0588 | U 92 Uranium 238.02891 | Np 93 Neptunium (237) | Pu 94 Plutonium (244) | Am 95 Americium (243) | Cm 96 Curium (247) | Bk 97 Berkelium (247) | Cf 98 Californium (251) | Es 99 Einstenium (252) | Fm 100 Fermium (257) | Md 101 Mendelevium (258) | No 102 Nobelium (259) | Lr 103 Lawrencium (262) |

Most chemical formulas involve subscripts that are numbers. While these numbers are not followed by units written in the formula, they are, in fact, quantities with units. Thus inherent in chemical formulas is the necessity of conversion factors, which are fractions that convert one unit to another when multiplied by a measurement. The process of using conversion factors is known as dimensional analysis, and it is vital to the study of chemical formulas and equations.

## Moles of Compounds to Moles of Elements

A mole is a unit of measurement of amount. If a whole number appears as a subscript in a chemical formula, it represents the number of moles of the element immediately preceding the subscript in the formula. If the subscript follows a set of parentheses, it represents the number of moles of the group of atoms in parentheses. The mole is useful because it helps you understand the relative amount of each element in a compound, and these amounts are given by the subscripts in the formula. For example, the formula for water is H2O, where the two is the subscript for hydrogen. There is no subscript after oxygen, which is the same thing as having a subscript of one. Therefore, one mole of the compound H2O contains two moles of hydrogen and one mole of oxygen, and the conversion factors are (2 moles hydrogen/ 1 mole H2O) and (1 mole oxygen/ 1 mole H2O), respectively.

## Moles to Atoms and Molecules

The unit of a mole is useful not only because it breaks a formula down into its chemical components, but also because of its relation to the number of atoms and molecules. One mole is 6.02 * 10^23 atoms or molecules, so the conversion factor is (6.02 * 10^23 atoms or molecules/ 1 mole). For example, one mole of carbon is equal to 6.02 * 10^23 atoms of carbon, and one mole of carbon dioxide is equal to 6.02 * 10^23 molecules of carbon dioxide. Since the formula of carbon dioxide is CO2, one mole of carbon and two moles of oxygen can be found in one mole of carbon dioxide. Thus 6.02 * 10^23 carbon atoms and 12.04 * 10^23 oxygen atoms exist in one mole of carbon dioxide.

## Moles to Grams

While it is important to understand moles and the number of atoms and molecules, a more practical unit for experiments is the gram, which is a unit of mass. You cannot measure a mole of a substance in a laboratory, but you can measure its mass in grams on a balance. The conversion factor for converting moles to grams comes from the periodic table. The atomic mass, which is usually given below the atomic symbol and atomic number, is the number of grams per mole of that element. For example, the atomic mass of germanium is 72.61 g/ mol. Therefore, the conversion factor is (72.61 g Ge / 1 mol Ge). The conversion factor for each element is analogous; simply replace the atomic mass of germanium with the atomic mass of the element being studied.

## Percents to Moles

Sometimes the subscripts in chemical formulas are not whole numbers but decimals. These are percents, and it is often necessary to convert percents to moles. For example, if you have a compound whose constituents are given in percents, like C0.2H0.6O0.2, then 20 percent of the moles of the compound are carbon, 60 percent are hydrogen and 20 percent are oxygen. To convert to moles, find the factor that multiply by the smallest percent to get a product of 100 percent. In this case the smallest percent is 20 percent, so that number is 5. Then multiply each percent by that number to get, in our case, the formula CH3O, since 20% * 5 = 100% = 1, and 60% * 5 = 300% = 3.