1. Day 5
Chapter 4 Section 2 and 3

2. Daily Problems (5) Introduction: What makes up the mass number?
Draw and label the subatomic particles of an atom. Charges.
Which particles account for most of an atom’s mass?
What does it mean to be electrically neutral?
Using your drawing identify the particles found in the nucleus. What is the charge of the nucleus?
If an atom is said to have a 3- charge what does that indicate?
3+ charge?

3. How atoms differ Start with some Vocab Atomic Number
Atoms total # of Protons
Atoms Total # of Electrons
Note: as long as the atom is neutral in charge
Atomic # identifies an atom of a particular element.
IT NEVER CHANGES!!!!
How to read the Periodic Table

4. Check Identify the following to fill in the chart. Name of element
# of Protons
Average Atomic Mass

5. Atomic numbers Composition of Several Elements Element Atomic Number
Complete the following table
Composition of Several Elements
Element
Atomic Number
Protons
Electrons a. Pb 82 b. 8 c. 30 82 82 O 8 8 Zn 30 30

6. Isotopes and Mass number
What do we know…?
Does the # of protons of an element ever Change? NO
Does the # of electrons of an element ever change?
What’s Left?
# of Neutrons will change
What does this mean?
Atoms with the same number of protons but different number of neutrons are called
“ISOTOPES”.

7. The mass number What makes up the mass number of an isotope.
Remember Relative Mass
Protons = 1amu
Neutrons = 1amu
What’s this mean?
If an element has 1 proton and 1 neutron what's the Mass Number? 2
So…The Mass Number is…
(Atomic #) + (# of neutrons)

8. What does all this mean? Elements have different forms in nature
Lets look at Copper…
How many protons in Copper?
29 protons
Does this ever change? No
But copper has two forms with different mass numbers.
What changes…# of Protons or # of Neutrons?
# of neutrons

9. Copper - isotopes Cu Cu Copper – 63 Copper - 65 Other ways to write it
Mass number
Other ways to write it Cu 63 29 Cu 65 29

10. Learning check # 1
Potassium – 39
Potassium – 40
Potassium - 41
Protons
Neutrons
Electrons 19 20 19 21 19 22 19 19 19
_____e-
_____e-
_____e- 19 19 19
_____p+
_____n
_____p+
_____n
_____p+
_____n 21 22 23
Now Write it! 39 19 40 19 41 19 K K K

11. Learning Check #2 Fill in the Chart
Isotope Composition Data
Element
Atomic #
Mass #
Protons
Neutrons
electrons
Symbol
Neon 10 22
Calcium 20 46 Ca
Oxygen 8 17
Iron 26 57
Zinc 30 64
Mercury 80
204
An atom has a mass number of 55. Its number of neutrons is the some of its atomic number and five. How many protons, neutrons and electrons does this atom have?
What is the identity of this atom?
30 neutrons, 25 protons, 25 electrons
Magnesium

12. Natural abundance In nature, elements are a combination of isotopes.
So, if the mass of Neon is the combination of all three isotopes, how do you calculate the atomic mass?

13. (Mass #1) (%) + (Mass #2) (%) + (Mass #3) (%)… = AMU
Natural abundance
Keep it simple…
Multiple the % (decimal form) by each mass.
Then add them together.
This will give you the Atomic Mass Unit (amu)
(Mass of isotope #1) (% decimal)
(Mass #1) (%) + (Mass #2) (%) + (Mass #3) (%)… = AMU

14. Learning check #3
Three magnesium isotopes have atomic masses and relative abundances of amu (79.99%), amu (10.00%), and amu (11.01%). Calculate the atomic mass of magnesium. Follow your rules.
(.7999) (.1000) (.1101) =
Nitrogen has two naturally occurring isotopes, N-14 & N Its atomic mass is Which isotope is more abundant? Common Sense!
N – 14 : it’s closest to the atomic mass

15. Homework assignment
Problems: , 39, 42, 46, 48, , 64

16. a look ahead Day 6: Isotope Lab / Quiz on the Atom
Day 7: Chapter 4 Section ¾
Day 8: Isotopes Quiz:
Chapter 24 Section 1
Day 9: Chapter 24 Section 2