QOTD 10/30/13

• Please pick up the QOTD on the half-sheet of paper up front.

• Do the questions on the half-sheet of paper• PLEASE HAVE YOUR HOMEWORK READY:

pages 97-100. I will check them now.

QOTD 10/30/13

• 1. a. 8 p+, 8 n0 = O- 16 yes – on band of stabiliity• 1. b. 90 p+, 130 n0 = Th-220 yes – on band of stability• 1. c. 80 p+, 40 n0 = = Hg-120 no – not on band of

stability• 1. d. 40 p+, 80 n0 = = Zr-120 no – not on band of

stability• 2. neutrons put space between the + charges of

neutrons. This helps cut down the electrostatic repulsion of protons.

AnswersPAGE 97, 1-9

#1. Did any of your atoms land outside the gray area? Explain why or why not.

No, otherwise they probably wouldn’t

exist.

#2. How can there be 2 different atoms of iridium?

Isotopes

#3. What does the line on the graph represent?

= # of protons & neutrons

#4. If an atom has the same # of neutrons as it does protons, will it be an isotope found in nature? Explain.

Only if it has <40 protons, otherwise it needs more neutrons.

#5. Two of the atoms you plotted are radioactive, that is their nuclei fall apart over time. Which two do you think they are? What is your reasoning?

U-238 & Ir-195 b/c

they are on the edge.

#6. Imagine a chemist was trying to create an atom with 60 protons and a mass # of 155. Would this be possible? Why or why not?

Well… sort of.Yes, but it won’t be stable

60 protons & 95 neutrons doesn’t fall in the band of stability.

#7. If an element had 90 protons, how many neutrons would be a good # for it to have in order to be considered a stable element? What element would this be?

125-135, Th

#8. What do you suppose that little island of gray on the graph represents?

More potential stable isotopes

#9. Which of the following isotopes are you likely to find? Identify the element by name if it is an isotope that you might find in nature.

?162

63 ?75

33 ?112

56 ?260

88 ?300

115

NO As NO NO Unnamed

AnswersPAGE 100

Check in• Use your graph to determine

how many neutrons you would need to make a stable element with 75 protons.

Between 95 and 115• How many neutrons would

make a radioactive element with 75 protons?

• Less than 95 or more than 115• Explain the relationship

between atom and isotope.• Atoms of the same element

can have different numbers of neutrons. These different atoms are isotopes.

Homework Answers

• 1. imagine an atom with a nucleus of 31 protons and 31 neutrons. Does this represent an element? Yup. It is Ga-62

• 2. find 5 radioactive elements on the periodic table. Name them. Determine the neutron to proton ratio.

• Anything with 84 or more protons. Example: Po-209 has 84 protons and 125 neutrons. So 125:84 ratio

• 3. How many protons could a stable atom with 90 neutrons potentially have? Which elements would these be?

• About 60-75 protons. So elements Nd-Re

Homework Qs

• 4. Which of these isotopes are likely to be found in nature?

• Just the second one!

• As-75