1. QOTD 10/21/13
HW check: Please get out the homework from Friday (p )
2. QOTD: Do the chem catalyst on page 59

2. ANSWERS to Lesson 1.3.2 Activity Questions

3. Protons (white) Nucleus
1. Label the electrons, nucleus, neutrons, and protons in the pictures above.
Neutrons (black)
Electrons
Protons (white)
Nucleus

4. 2. Each atom is neutral. Explain why.
There is always an equal number of electrons (negatively charged) and protons (positively charged)
Example: 4 protons and 4 electrons

5. 3. How did you know which were the protons and which were the neutrons?
Number of electrons is the same as number of protons.
Usually # n0 > # p we will see why when we study radioactivity

6. 4. Is the nucleus of these atoms positive, negative, or neutral
4. Is the nucleus of these atoms positive, negative, or neutral? Explain your reasoning.
The nucleus is positive because it only contains protons (positively charged) and neutrons (no charge).

7. 5. Use a periodic table to fill in table 1.3.2 on the following page.
See the PDF file

8. 6. How did you figure out the number of electrons in each atom?
As long as we assume the atom is neutral (no overall charge), the number of electrons is equal to the # of protons.
Note that it is possible to add or remove electrons from an atom and thus make the atom have a + or – charge! We call these ions

9. It’s ALWAYS the same as the atomic number.
7. How did you figure out the number of protons in each atom?
It’s ALWAYS the same as the atomic number.

10. You take the mass number and subtract the number of protons.
8. How did you figure out the number of neutrons in each atom?
You take the mass number and subtract the number of protons.

11. It’s the rounded whole number of the atomic weight.
9. How does the mass number of each atom compare to the atomic weight given on the periodic table?
It’s the rounded whole number of the atomic weight.

12. 10. Make a drawing of a nitrogen atom, similar to those given for beryllium, fluorine, and carbon.
7 protons, 7 neutrons, 7 electrons

13. Chem catlyst page 59 (QOTD)
What is different?
The one on the right has one more neutron
What are the atomic numbers?
Both are 3
What are the mass numbers?
Left: right: 7
Do you think they are both lithium?
Yes! Both have 3 protons

14. Today’s Learning Target
You should be able to:
Describe what an isotope is and write isotope symbols
Determine what isotope is most prevalent for a given element

15. Note Time! Find a spot in your notebook for some notes.
Title it “isotope notes” or something like that
Don’t forget to put it in your TOC!

16. Isotopes
Isotopes – atoms of the same element but with different mass numbers
Same number of protons
Different numbers of neutrons

17. Atomic mass Atomic mass – the mass of a single atom
Measured in unified atomic mass units (u)
1 u is defined as exactly 1/12th of an atom of carbon-12
1 proton = 1 u neutron = 1 u
1 u is TINY : 1 u = 1.66 x g
Or x 1023 u = 1 g
you WILL memorize this number later. It is called the “mole”

18. Isotope Names and Symbols
We name isotopes by their mass number
Ex: carbon-14
We can write this in shortand using symbols
Ex: 14C
superscript = mass number
Subscript = atomic number 6

19. Practice How many protons does helium-3 have? How many neutrons?
What is the mass number?
What is the chemical symbol for helium?
Write the chemical symbol for the helium-3 isotope

20. Assignment/HW Complete p. 60-64 Skip “if you finish early” on page 61
Skip Qs 7 and 8 on p. 64