Practice Quiz

1. Aluminum _____

2. Zinc _____

3. Bromine _____

4. Sodium _____

5. Flourine _____

6. Gold _____

7. Copper _____

8. Nickel _____

9. Ca __________

10. C__________

11.Mg __________

12.Hg __________

13. Zn __________

14. Cl __________

15. K__________

16. Sn __________

• Atomic Number–Protons

–Electrons (for now)

• Atomic Mass–Protons + Neutrons

9

F19.0

• Neutrons = atomic mass – atomic number• Periods/Energy levels are rows that go across• Families/Groups columns that go up & down• Electrons in outer energy level – same as column

How Atoms Differ• Periodic Table

– Ordered by the number of protons

• the only thing about an atom that doesn’t change!

• If you change proton number you change the element

Mass of Individual Atom

• Mass of proton or neutron = 1.67 x 10-24 g

• Mass of electron = 9.08 x 10-28 g

or 1/1840 the mass of proton

• Atomic Mass = weighted average of the isotopes of an element

How to calculate Atomic Mass• The same as calculating your grade

% of your grade

Your average

Calculations

Homework 10% 88Quiz/Test 30% 80

Final 60% 72

...)100

%()

100

%( 2

2

1

1

amuamuAverageWeighted

Let’s Practice1. Calculate the atomic mass

107Ag 106.905 amu 52%109Ag 108.905 amu 48%

...)100

%()

100

%( 2

2

1

1

amuamuAverageWeighted

Let’s Practice2. Calculate the atomic mass

1H 12%2H 48%3H 40%

Let’s Practice3. Boron has two naturally occurring

isotopes, boron-10 (abundance 19.8%, mass 10.013 amu) boron-11 (abundance 80.2%, mass=11.009 amu)

Calculate the average atomic mass

Let’s Practice4. Calculate the average atomic mass

12C 12.0014 amu 87.3%14 C 13.9960 amu12.7%

Let’s Practice5. Calculate the average atomic mass

Iron-55 67.8%

Iron-58 32.2%

Let’s Practice6. Calculate the atomic mass

Helium has two naturally occurring isotopes, helium-3 and helium-4. The average abundance of helium-3 is 27.2%, and the average abundance of helium-4 is 72.8%