1. Unit 5 lec 2- Subatomic particles
What information would you get about an element from the periodic table?

2. The atomic number and mass are used to determine the number of protons, neutrons, and electrons in an atom

3. # of Protons = atomic number
# of Neutrons = Mass number – atomic number
this works because…
Mass number = protons + neutrons,
so if you take away the atomic number you are left with neutrons.
# of Electrons = atomic number (for neutral atoms)

4. What is its atomic number and atomic mass?
A bohr model of an atom. Notice the protons and neutrons in the nucleus and the electrons outside the nucleus s
Which element is this?
What is its atomic number and atomic mass?

5. For each symbol, specify the number of p,n,& e-
Protons
Neutrons
Electrons
24He 2
612C
1735Cl
49Be

6. For each symbol, specify the number of p,n,& e-
Protons
Neutrons
Electrons
24He 2
612C 6
1735Cl 17 18
49Be 4 5

7. Draw a Bohr model for an atom of each of the following Include where the protons, neutrons and electrons are located, include the proper number of protons, neutrons, and electrons, also identify the nucleus and electron clouds.
Boron
Flourine

8. Lewis dot structures
Valence electrons – electrons in the highest occupied energy level/orbital of an atom
Maximum of 8 valence electrons
Use the periodic table to determine!

9. Why are valence electrons so important?
Tells us the chemical properties of an element
They are responsible for the formation and breaking of bonds

10. Lewis dot structures
We use Lewis dot structures to show the number of valence electrons within an element

11. Draw Lewis dot structures for
Carbon
Sulfur
Boron

12. Isotopes of Atoms: These are three isotopes of Hydrogen

13. 4. What does the mass number tell you?
2. What structural characteristics do all three hydrogen atom isotopes have in common?
3. How does one isotope of hydrogen differ from another isotope of hydrogen?
4. What does the mass number tell you?
5. What does the atomic number tell you?
6. Define the term isotope.

14. Average Atomic Mass:
Notice how the atomic masses are NOT whole numbers. (For example the atomic mass of sodium is NOT 23).
These are the average atomic masses for elements.
This is a weighted average so more abundant (common) isotopes have a bigger effect than less abundant ones.
Av. At.mass = ( percent abundance/100) mass A + ( percent abundance/100) mass B

15. Average Atomic Mass: 1. What if the teacher decided that test 1 would count for 40% of the final grade, test 2 would count for 35% of the final grade, and test 3 would count for 25% of the final grade. Calculate the new WEIGHTED AVERAGE for each student.

16. Average Atomic Mass:
1. What if the teacher decided that test 1 would count for 40% of the final grade, test 2 would count for 35% of the final grade, and test 3 would count for 25% of the final grade.
Student A:  
Student B:

17. Average Atomic Mass:
2. Suppose that student C had an average of 85. On each of his three tests he scored either 65 or 95. Which score occurred more often? EXPLAIN.

18. Now lets do this with isotopes in chemistry!
1. Neon has three different isotopes % of neon atoms have a mass of amu % of neon atoms have a mass of amu % of neon atoms have a mss of amu. What is the average atomic mass of neon?
2. Of all chlorine atoms, % are chlorine 35. Chlorine 35 atoms have a mass of amu. All other chlorine atoms are chlorine-37 with a mass of Calculate the average atomic mass of chlorine.

19. 3. Calcium has three different isotopes. One has a mass of 35
3. Calcium has three different isotopes. One has a mass of amu; another has a mass of amu, and a third has a mass of amu. Which isotope is most abundant of the three? (HINT: look at the periodic table). 4. An element exists with three isotopes. 24.1% have a mass of amu, 48.7% have a mass of amu, and 27.2% have a mass of amu. What is the average atomic mass of this element? Using your periodic table identify which element this is.