1. Atoms, particles, and moles,…. Oh My!!!!
Week 21 CCA
Atoms, particles, and moles,…. Oh My!!!!

2. . DO NOT ENTER x 10 Scientific Notation 6 2 2 3
Open (
Enter 6.02
2nd (Blue or Yellow button)
EE ( , button above 7)
Type in the exponent 23)
Your screen looks like: (6.02E23)
DO NOT ENTER x 10
2nd
Open (
Close ) EE 6 2 2 3 .

3. Use SIGNIFICANT FIGURES to answer
All non-zero numbers are significant
EX: is 3 sig.figs., 19 is 2 sig.figs., etc.
All zeros between numbers are significant—
EX: is 4s.f., 2.07 is 3 s.f., is 4 s.f. (captive zeros)
All zeros to the right of numbers aren’t significant if there’s no decimal
EX: 1200 is 2s.f., 1000 is 1. (trailing zeros)
All zeros to the left of numbers aren’t significant if there’s no number in front
EX: is 2s.f. (Leading zeros)
All zeros after a number and a decimal are significant
EX: is 3 s.f is 4 s.f.
When multiplying and dividing, use the least number of significant figures in your answer.
When adding and subtracting, use the least number of decimal places in your answer.
You calculate as the answer to a problem. What would your answer be if you were asked to round to three significant figures?
LOOK AT YOUR FORMULA SHEET FOR THE RULES! ! !

4. There is nothing “Heavenly” about these seven diatomic molecules if you forget how to use them
1 mole of H2 = g/mole
1 mole of O2 = g/mole

5. MOLAR MASS Steps in Solving Molar Mass Problems:
If the chemical formula is not given to you, determine the correct chemical formula of the compound.
Use the subscripts in the chemical formula to determine how many moles of each given element are present in one mole of the compound.
Add up the masses of each of the elements present in the compound to determine the Molar Mass of the compound.

6. Gram-Moles-Atoms Conversion
Steps in Solving GMA (grams↔moles↔atoms) Problems:
Determine the Molar Mass of the compound using the process above.
Follow the GMA map performing each calculation using either the molar mass or Avogadro’s number (6.02x1023).

7. Mole Road Map Method T= 273 K or 0°C P= 1 ATM If not STP, then use the
Volume
of gas
(STP)
T= 273 K or 0°C
P= 1 ATM
If not STP, then use the
Combine Gas Law:
1 mol
22.4 L
22.4 L
1 mol
Mole
Objective:
What do you do if you are asked to convert between two units, and neither one is the mole?
When calculating chemical quantities, everything goes through the ________________________
If neither of your units is a mole, you will need a ____________-step conversion problem.
One ________________ ______________ to go from the given units to __________________, and a second conversion factor to go from moles to the ______________________ units.
You know we are talking about MASS if the units are _________________.
You know we are talking about VOLUME if the units are ________________.
You know we are talking about particles if the units are ________________, _________________, or _________________ ______________.
Molar mass
1 mol
Representative Particles
1 mol
6.02x1023 particles
Mass
6.02x1023 particles
1 mol
(atoms, molecules, or formula units)
(grams)
1 mol
Molar mass

8. Molecules MOLES Volume
Calculate the volume, in liters, of 3.24 x 1022 molecules of Cl2 (STP).
You can not take the mass of a gas. You will need to use the conversion factor
{ 1 mole = 22.4 Liters}
3.24 x 1022 molecules Cl2 x mol x L Cl2 =
x 1023 molecules mol
1.21 L Cl2

9. General Mole Questions
How many atoms are in 1 mole of any element?
What is the unit for molar mass?
How many atoms are in the compound CoCl2?
List the seven diatomics.

10. Molar Mass What is the molar mass of Sr(OH)2 ?
What is the molar mass of iron (III) nitrate?
What is the mass in grams of one mole of Neon?
What is the number of moles of F-1 ions in CaF2?

11. Mole Conversions
Calculate the number of molecules in 2.0 moles of H2O.
How many moles of Ag contain 2.49 X 1023 atoms of Ag?
A hot air balloon contains 9.0 X 1022 atoms of helium (He) gas. Calculate the mass of helium in grams.
How many atoms of nickel (Ni) are in a pure nickel coin weighing 28g?
Calculate the mass in grams of moles of MgO.
How many moles of hydrogen gas (H2) are in 425 grams of hydrogen gas?
How many moles of Neon (Ne) are present in 12.4 L of neon gas at STP?
How many oxygen molecules are in 3.36 L of oxygen gas at STP?
Determine the volume in liters occupied by 24 g of nitrogen gas N2 at STP.
How many Hydrogen atoms are in 1 mole of CH4?

12. Play & Keep Up! Play the Game
Take the Test. Print copy or screen shot to your Chemistry teacher for 10 bonus points.

13. STILL HAVING PROBLEMS? Crash Course