Atoms and the Periodic Table Counting Atoms with

Atoms and the Periodic Table Counting Atoms with the Mole

Objectives: l l l Explain the relationship between a mole of a substance and Avogadro’s constant. Find the molar mass of an element by using the periodic table. Solve problems converting the amount of an element in moles to its mass in grams, and vice versa

Before We Get Started l l l Consider a plastic container with markers. What is the mass of the markers? Plan with your critical thinking partner a way to measure the mass of the markers without the mass of the container. Keep it simple, you have a balance beam and the container of markers.

Quick Check l l l What is an Atomic Number? What is Atomic Mass? What is an amu? What is an Isotope? What is a Mole?

Measures & Counting l l There are many different ways of counting things We may use different units Give examples of ways to count different things Dozen Eggs, Dollars, Screws in a Jar

The Mole l l The Mole is the SI base unit used to measure the amount of a substance It is based upon the number of atoms in 12 grams of carbon-12

Avogadro's Constant l 6. 022 x 1023/mol l The number of particles in 1 mol of a substance

Molar Mass l l l The mass in grams of 1 mol of a substance The amount of a substance and its mass are related Using the average mass of an element we can determine conversion factors

Conversion Factor l The ration that is derived from the equality of two different units and that can be used to convert to another 207. 2 grams 1 mol Pb

Example l 10 white balls has a mass of 23 grams 10 white balls What if we had 50?

Math Skill 50 white balls ∙ 23 grams 10 white balls = 115 grams (the red units cancel)

Lets do that with Moles 50 Mol Na ∙ 22. 989770 grams 1 Mol (the red units cancel) = 149. 4885 grams Na

What if I Had Grams? 149. 4885 g Na ∙ 1 Mol 22. 989770 g (the red units cancel) = 50 Mol Na This is how we would reverse the process

What do you know? l l l What is the relationship between Avogadro’s constant and 1 mol? What is the difference between Atomic Mass and Molar Mass? Molar Mass is measured in amu T or F

Conversion Practice Get with your critical thinking partner