QOTD 10/22/131. Come grab a copy of the pennium “lab” activity from

the front counter

2.HW check: please get out the HW assignment (p 60-64)

3. QOTD: work on page 2 of the handout (atomic structure review table) while I check homework

ANSWERS to Lesson 1.3.3 Activity Questions (pg 60-

62)

1. Use the pictures of the 10 atoms above to complete the first data table.

5 5 5 5 5 5 5 5 5 5

5 5 5 5 5 5 5 5 5 5

5 6 6 6 6 5 6 6 6 6

2. How many different isotopes of boron are pictured above? Explain what they are.

2 that have 5 neutrons and 8 that have 6 neutrons

3. How many of each type of isotope are present in the sample of 10 atoms?

2 Boron-10, 8 Boron-11

4. What is the atomic mass of each type of isotope? How did you arrive at your answer?

10, 11 (protons + neutrons = atomic mass for each atom)

5. How would you figure out the average atomic mass of the ten atoms?

a) Complete the calculation and show your work.

b) How does your answer compare to the atomic weight of boron listed in the periodic table?

(2 x 10) + (8 x 11) = 10.8 10

It’s the same as on the periodic table!

6. Imagine you were able to examine 100 atoms of boron.

a) What are the mass numbers of the isotopes you expect to find?

b) How many atoms of each isotope would you expect to find?

c) Express your answers in %s.

Boron-11, Boron-10

80 Boron-11, 20 Boron-10

80% Boron-11, 20% Boron-10

7. Complete the second table.

5 10.81 5 5

17 35.45Cl 1718 or

19

3Li 3 3 or 43

50.94 23 23 27 or 28

14.01 77 7 or 8N

24.31 1212 12 or 13Mg 12

1818 18

8. How many isotopes does argon have?

3

9. Which isotope of argon is the most commonly found? Explain your reasoning.

22 because the average atomic

mass is close to 40.

10. If you somehow managed to have a single atom of lithium isolated, how many neutrons will it probably have in its nucleus? Explain.

4, the average atomic mass is close to 7

ANSWERS to HOMEWORK 1.3.3

Questions 1-6 (page 64)

Check-in: Carbon has 3 isotopes, with masses of 12, 13 and 14. Which isotope is the most abundant? How do you know?

Carbon 12—it’s closest to the average atomic mass on the periodic table (12.011)

1. Explain the different between atomic number and atomic mass.

Atomic number is = to the number of protons while the atomic mass is an average mass of all atoms of that element including isotopes.

2. Explain the different between the average atomic mass given on the periodic table, and the mass number of an atom.

Mass number is the number of protons + neutrons for a single atom while the average atomic mass includes all isotopes of a given element.

3. There are 3 isotopes of potassium, potassium-39, potassium-40, and potassium-41.

a. What do these isotopes have in common?

b. What makes these isotopes different from each other?

c. Write the isotope symbols for each of these three isotopes.

They all have 19 protons

They have different numbers of neutrons

K K K19

39 4019 19

41

4. How many protons, neutrons, and electrons are in each of the following atoms?

a. Fluorine-23 b. Co c. Zinc-70

Protons: 9Neutrons: 14Electrons: 9

59

27

Protons: 27Neutrons: 32Electrons: 27

Protons: 30Neutrons: 40Electrons: 30

5. An isotope of iron has 26 protons and 32 neutrons.

a. What is the mass of this isotope?

b. Write the symbol for this isotope.58

Fe26

58

6. Find the element phosphorus on the periodic table.

a. What is the average atomic mass of phosphorus?

b. What is its atomic number?

c. Predict which isotope of phosphorus is the most common. Explain.

30.97

15

Phosphorus-31 (closest to the average atomic mass)

Today’s learning target:

Be able to determine the atomic masses of different isotopes and calculate average atomic mass

We will do this for the imaginary element “Pennium” (Pe)

Pennium: Come get a cup of pennies.

Make sure you have 20 pennies.

Make sure to weigh EACH penny INDIVIDUALLYMake sure you record the DATE of each penny!

Due: tomorrow