Candium Lab

10/8 Objective: Students will mass three isotopes of the fictitious element candium and determine the atomic mass for candium.

Isotopes Review

1. What 3 things are the same in an isotope?

-What 2 things are different?

2. Identify number of p, n and e in

protons, electrons, atomic number

neutrons, mass number

Protons Neutrons Electrons

Carbon-12 6 6 6

Carbon-13 6 7 6

Carbon-14 6 8 6

3. What is the atomic mass for carbon?

4. How is atomic mass calculated?

5.What isotope of carbon is the standard for atomic mass?

12.0107 amu

Average all the mass numbers of all isotopes of an element

Carbon-12

Isotopes Review

6. Regarding Carbon-12, 12 is the

________ _____.

7. An element has atomic number 8 and mass number 17. How many neutrons does it have? What element is it?

atomic mass

9oxygen

Isotopes Review

Calculating Average Atomic Mass

12 + 13 + 14 = 13 3

C-12 + C-12 + C-12 + C-13 + C-14 = 12.6 5

The more isotopes of carbon-12, the atomic mass average is closer to 12

C Carbon

Math Example (avg):

Chemistry Example (avg mass):

Procedure:

1. Obtain a sample of candium.2. Separate all the candium isotopes by type.3. Count the number of particles in each isotope type

and record each total.4. Mass the particles of isotope candium-A, isotope

candium-B, and isotope candium-C, then record the total mass for each group. Use weighing paper!!!

5. Determine the average mass of each candium isotope by dividing the total mass of that particular isotope by the number of particles of that particular isotope .

6. Add the total mass of isotope candium-A, isotope candium-B, and isotope candium-C to get the total mass for candium.

7. Calculate the percent abundance of each candium isotope (hint: all percents should up to 100%)

Record your Data:Mass and record your data on this table for each candium isotope on this data table.

of “particles”

How to Calculate Percent Abundance?

Example Question:

Calculate the percent relative abundance of the following 2 isotopes with an average atomic mass of 63.546 g for Cu?

-Cu-63 mass = 62.9296 g-Cu-65 mass = 64.9278 g

-The avg. mass of Cu is 63.546 g

The Steps:

Let (x) be the fraction of Cu-65. Then (1.0 – x) be the fraction of Cu-

63

“100%”

(64.92)x + (1.0-x)(62.92) = 63.54

64.92x + 62.92 - 62.92x = 63.54

2x = 0.62

x = 0.31; then 1.0 - x = 0.69

So, 31% Cu-65

69 % Cu-63

Analysis1. Does every isotope of candium have the same mass?

Explain.

2. What factor makes each isotope different?

3. Carbon has three different isotopes: carbon-12, carbon-13 and carbon-14. Explain how the three isotopes of candium relate to the three isotopes of carbon.

4. What isotope is the standard used for calculating atomic mass on the periodic table?

Conclusion

Explain each of these aspects of the lab:• Objective• Atomic Mass• Carbon• Candium• Data• Possible error? (changes?)

In a short paragraph…

There will be a quiz!!!

You will be expected to answer questions about this lab and pass with 80% accuracy. You will not be able to perform the lab if you do not pass the quiz…PASS THE QUIZ!!!