Alchemy Unit – Investigation IV

Lesson 1:

Island of Stability

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

Admit Slip The isotope notation for an atom of copper and an atom of gold are given below.

• How could you change a copper atom into a gold atom?

• What would you need to change? Give specific numbers.

• Why is this change called a nuclear reaction?

Cu63

29Au

197

79

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

Isotope Review

Copper-63

29 protons

29 electrons

63 – 29 = 34 neutrons

Cu63

29Au

197

79

Bottom #: Atomic Number (Number of protons)

Top #: Mass Number

Gold-197

79 protons

79 electrons

197 – 79 = 118 neutrons

Neutrons = mass - protons

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

The Big Question

• What is the range of the number of neutrons found in isotopes of various elements?

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

Objective:

Students will be able to determine how many neutrons are required to make a stable element with a given number of protons.

Agenda:Admit Slip

Homework Review

Notes

Classwork

Exit Slip

Grade Update

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

Homework Review

1.

They have different numbers of neutrons and different masses.

2. Fluorine-23: 9p 9e 14n : 27p 27e 32n

Mo-96: 42p 42e 54n

3. a) The mass is 58 amu.

b)

€

1838Ar

€

1840Ar

€

1836Ar

€

2658Fe

€

2759Co

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

Homework Review

4. a) Atomic Mass = 30.97

b) Atomic Number = 15

c) Phosphorus-31 will be more abundant because 30.97 is closest to 31.

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

• Nuclear chemistry is the study of the nucleus of the atom.

• The band of stability is the range in the number of neutrons for a given number of protons for stable isotopes that are found in nature.

• Atoms that exist for a long time are referred to as stable.

Atom Stability 9 / 26 / 13

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

• Radioactive elements are unstable because they decay over time as pieces of the nucleus break apart.

–Radioactive atoms break down into other elements.

• Any isotope that is around long enough to be detected and measured qualifies as an element, but still can be highly unstable and radioactive.

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

Activity

Purpose: Some combinations of neutrons, electrons, and protons are not stable enough to be called elements. This lesson shows you how to predict the numbers of neutrons, electrons, and protons of the isotopes they are likely to find in nature.

(cont.)

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

(cont.)

(cont.)

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

Making Sense

• What kind of generalization can you make about how the number of protons and neutrons are related to each other in the elements?

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

Exit Slip

• Use your graph to determine how many neutrons you would need to make a stable element with 75 protons.

© 2004 Key Curriculum Press.

Unit 1 • Investigation IV

Wrap-Up

• In order for an atom to be considered an element, it has to have a stable nucleus and exist long enough to be detected.

• The neutron to proton ratio is an important factor in determining the stability of a nucleus.

• Some isotopes are more stable than others. Unstable isotopes undergo nuclear decay to produce atoms with lower mass.