1. Good Morning! Today is Wednesday, October 7, 2015 Do-Now: Convert the following measurement: 100 km = ______ miles HW Due: Can You Fix It? – Dimensional Analysis Style

2. Elements How is an element defined? An element is any matter that is made up of only one type of atom! For example, a piece of iron only contains iron atoms Which of the pictures below represents an element? The one on the left!

3. Elements So, are all of the atoms inside an element identical? No! Why are they not all identical? Isotopes! 56 Fe 54 Fe 56 Fe 54 Fe 56 Fe 57 Fe 54 Fe 56 Fe 57 Fe 56 Fe 58 Fe

4. Let’s Look Inside a Piece of Iron! Remember: Only one type of atom is in an element In this case, we only have iron atoms All atoms in an element will have the same number of protons and electrons But, the atoms will have a varying number of neutrons 56 Fe 54 Fe 56 Fe 54 Fe 56 Fe 57 Fe 54 Fe 56 Fe 57 Fe 56 Fe 58 Fe

5. Atomic Mass Think back to last week: Atomic masses of isotopes are different due to different mass numbers The periodic table displays an average atomic mass of the isotopes for each element

6. Atomic Mass Masses of atoms are too small to utilize units of grams We use atomic mass units (amu) Iron = 55.845 amu Grams are the units that are going to be helpful to us in the lab, not amu If there are the right number of atoms in a sample, then the atomic mass can be written in grams

7. How Many Atoms Do We Need? A Mole!

8. Let’s Think About Other Measurements We Know! How many items are in a: Dozen? Pair? Baker’s Dozen?

9. What is a Mole? Is a mole the: Animal? Spy? Sauce?

10. A Mole is… A measurement used to represent a certain number of things A dozen is equal to 12 things A mole is equal to 6.02 x 10 23 things 1 mole of donuts = 6.02 x 10 23 donuts 6.02 x 10 23 students = 1 mole of students

11. Moles Related to Atoms If I have a mole of atoms in a sample, then I have… 6.02 x 10 23 atoms If we have a sample of an element that contains a mole of atoms, or 6.02 x 10 23 atoms: The sample has a mass that weighs the same as the atomic mass on the periodic table in units of grams!

12. Mole Equation 6.022 x 10 23 atoms = 1 mole = Atomic Mass in grams

13. Example 6.022 x 10 23 atoms of iron = 1 mole of iron = 55.845 grams of iron

14. Review 1 atom of iron = 55.845 amu 6.022 x 10 23 atoms of iron = 55.845 g of iron

15. Elements and the Mole Practice Problems #1-6

16. Review of Practice Problems 1. How many atoms are in 1 mole of oxygen? 6.02 x 10 23 atoms of O 2. How much does 1 mole of oxygen weigh in grams? 15.999 g of O 3. How many atoms are in 12.011 grams of carbon? 6.02 x 10 23 atoms of C 4. How many moles of carbon are equal to 6.02 x 10 23 atoms of carbon? 1 mole of C 5. How many moles of silver are equal to 107.87 grams? 1 mole of Ag 6. How many grams of silver are equal to 6.02 x 10 23 atoms of silver? 107.87 g of Ag

17. Homework Complete the “Elements and the Mole Problems” for tomorrow Your “History of the Atom Timeline” is due on Friday 10/09