COUNTING ATOMS AND MOLECULES: The Mole Mr. Tsigaridis

How do we interpret a quantity? In chemistry, as in everyday life, special units are derived to make counting and measuring objects an easy task…. See if you know any of the following:

A Bale A large bundle of goods. In the U.S., the approximate weight of a bale of cotton is 500 pounds. The weight varies in other countries.

A Carat 200 milligrams or 3.086 grains troy. Originally the weight of a seed of the carob tree in the Mediterranean region. Used for weighing precious stones.

Horsepower The power needed to lift 33,000 pounds a distance of one foot in one minute (about 11/2 times the power an average horse can exert). Used for measuring power of steam engines, etc.

A Span 9 inches or 22.86 cm. Derived from the distance between the end of the thumb and the end of the little finger when both are outstretched.

An Acre An area of 43,560 square feet. Originally, the area a yoke of oxen could plow in one day.

Other common measures Gross Ream Stone 12 dozen or 144 500 (commonly paper) 14 pounds

yotta [Y] 1 000 000 000 000 000 000 000 000 = 10^24 zetta [Z] 1 000 000 000 000 000 000 000 = 10^21 exa [E] 1 000 000 000 000 000 000 = 10^18 peta [P] 1 000 000 000 000 000 = 10^15 tera [T] 1 000 000 000 000 = 10^12 giga [G] 1 000 000 000 (a thousand millions = a billion) mega [M] 1 000 000 (a million) kilo [k] 1 000 (a thousand) hecto [h] 100 (a hundred) deca [da]10 (ten) 1 deci [d] 0.1 (a tenth) centi [c] 0.01 (a hundredth) milli [m] 0.001 (a thousandth) micro [µ] 0.000 001 (a millionth) nano [n] 0.000 000 001 (a thousand millionth) pico [p] 0.000 000 000 001 = 10^-12 femto [f] 0.000 000 000 000 001 = 10^-15 atto [a] 0.000 000 000 000 000 001 = 10^-18 zepto [z] 0.000 000 000 000 000 000 001 = 10^-21 yocto [y] 0.000 000 000 000 000 000 000 001 = 10^-24

The Mole One mole of any substance has the same number of entities in it. To understand, use the reaction of Sodium and Chlorine to make salt Na + Cl  NaCl This means that one mole of sodium combines with one mole of chlorine to make one mole of salt…

How big is a Mole? A mole is the amount of Carbon atoms that make up 12.01 grams of Carbon. This means that the atomic mass units of the nucleus (protons + neutrons) will equal the mass in grams of Carbon. Then the number of atoms of Carbon was calculated and this number is a mole of Carbon…

Avogadro’s Number It was determined that the number of carbon atoms in 12.01 grams is 602000000000000000000000 atoms This is Avogadro’s number, named after the scientist who calculated it 23 For simplicity use 6.02 x 10

Avogadro’s Number Avogadro's number is approximately a million billion billion. To get an appreciation of how large this number is consider having this much money. Last year the United States of America spent about one trillion dollars (a thousand billion). If you had and Avogadro's amount of money you could spend a trillion dollars a second for the next ten thousand years!!! It allows us to determine the molar mass for each element on the periodic table.

The Calculations Moles (n) x NA = Number of particles(N) Number of particles(N) / NA = Moles (n)