Scientific Notation and moles  atoms

Why Scientific Notation? In chemistry, we will often times run into very big or small numbers Single gram of hydrogen has about 602000000000000000000000 hydrogen atoms This is annoying

Scientific Notation Easy way to represent very large or very small numbers. Keep all numbers that are significant! A number between 1 and 10 multiplied by the appropriate power of 10. A positive exponent-- A very large number A negative exponent– A very small number

Scientific Notation Practice 1,200 296,000 93,000,000 1,500,000 1.2 x 103 2.96 x 105 9.3 x 107 1.5 x 106 0.000257 0.0000012 0.0420 0.0003 2.57 x 10-4 1.2 x 10-6 4.20 x 10-2 3 x 10-4

Practice with Sci Notation Convert the following into scientific notation: 3,021,000,000 2,100,000 0.000756 0.00201 0.00046 502,000 Convert the following to standard notation: 6.02 x 108 4.5 x 10-2 1.00 x 10-6 7 x 109

A. What is the Mole? VERY A large amount!!!! A counting number (like a dozen) Avogadro’s number 1 mol = 6.02  1023 items A large amount!!!! VERY

HOW LARGE IS IT??? 1 mole of hockey pucks would equal the mass of the moon! 1 mole of basketballs would fill a bag the size of the earth! 1 mole of pennies would cover the Earth 1/4 mile deep!

B. Dimensional Analysis The “Factor-Label” Method Units, or “labels” are canceled, or “factored” out

Convert between atoms and moles Now we can convert using our new unit! 1 mole = 6.02 x 1023 atoms So we can use these two fractions to help… 1 mole_____ 6.02 x 1023 atoms 6.02 x 1023 atoms 1 mole

C. Molar Conversion Examples How many moles of carbon would you have if there are 4.2 x 1022 atoms of Carbon? 1 mole C 6.02 x 1023 atoms C 4.2 x 1022 atoms C x = 0.070 mol C

C. Molar Conversion Examples How many atoms of oxygen would you have if there are 3.5 moles of Oxygen? 6.02 x 1023 atoms O 1 mole O 3.5 moles O = 2.1 x 1024 atoms O

Practice mole-atom conversions Complete the calculations: How many moles of Iron would you have if you have 1.45 x 1030 atoms of Iron? How many atoms of Copper would be present in 54.2 moles of Copper?

B. Molar Mass Mass of 1 mole of an element or compound. Atomic mass tells the... atomic mass units per atom (amu) grams per mole (g/mol) Round to 2 decimal places

B. Molar Mass Examples carbon aluminum zinc 12.01 g/mol 26.98 g/mol

C. Molar Conversion Examples How many moles of carbon are in 26 g of carbon? 26 g C 1 mol C 12.01 g C = 2.2 mol C

C. Molar Conversion Examples How many grams of Sodium are present in 2.8 mol Sodium? 2.8 mol Na 22.98 g Na 1 mol Na =64.34 g Na

Homework Tonight 1 mole = 6.02 X 1023 atoms or molecules Determine if you are using grams or atoms. 1 mole = 6.02 X 1023 atoms or molecules 1 mole = # grams from periodic table Warning! You MAY need to use BOTH! Follow your units...they will show you the way