Nuclear Chemistry – Chapter 25, chapter 4, section 4.4

Nuclear chemistry is the study of the ________________ of atoms and the ____________________ they undergo.

What makes an ordinary chemical reaction different than a nuclear reaction?

Chemical Reactions	Nuclear Reactions
Bonds are ____________ and reformed.	Nuclei release particles and rays of __________
Atoms ____________________ but are unchanged in structure.	Atoms are often __________________into atoms of another element.
Involve only ____________________ electrons	Can involve protons, neutrons, and even ____________________
Small _________________ changes occur .	________________ energy changes occur
Rate of the reaction is influenced by ____________________, pressure, concentration, and ________________________.	Rate of the reaction is not effected by the factors

The Nucleus

Ø Contains __________________ and neutrons. They are collectively called _____________________.

Ø There are 2 forces within the nucleus. _______________________________ where protons repel other protons. (___________________________________). The other is called a ______________________ which keeps the protons and neutrons together.

Ø A _____________________ nucleus holds together well.

Band of Stability

What causes a nucleus to decay?

Ø Some atoms decay (__________________________) because they have unstable nuclei.

Ø Elements falling ____________ or below the band of stability are unstable and are called __________________________. They will decay releasing a particle and/or_________________.

Transmutation

Ø Type of nuclear reaction that will change the number of ___________________ and thus will create a different ________________________.

Types of Radioactive Decay

Type Symbol What Happens? Example Penetrating Power

Alpha (Happens to elements above#83)	or	Atomic number decreases by ____ and mass number decreases by ____2	(1) LOW: Can be blocked by the skin
***Beta (Happens to elements with a high n/p ratio)	or	Atomic number increases by _____ but the mass number stays the same	(100) MEDIUM: can penetrate the skin; need to be protected by clothing
Gamma		No change in atomic nor mass number; occurs with other types of ____________	(100000) HIGH: need to be protected by lead

*** A neutron becomes a ________________ and a high speed electron that is discharged from the nucleus.

Writing Balanced Nuclear Equations

The ______________________ and mass number must be _____________________ on both sides of the equation.

Alpha Decay of thorium-230

Beta Decay of thorium -234

You Try!

1. Beta decay of zircomium-97

2. alpha decay of americium-241

3. alpha decay of uranium-238

4. Complete this: 239 239

Np à Pu + ___________

93 94

Bombarding the Nucleus

Ø All _________________________ elements( ____________________) are made through this process in nuclear reactors and _________________________________.

Example:

Half Life

Ø Radioactive isotopes decay at a characteristic rate measured in ____________________.

Ø A half life is the time required for _____________ of the radioactive nuclei to decay. They range from __________________ to millions of _____________________.

T= elapsed time

T_1/2 = half life

HOW TO’s

1. To calculate the number of half lives, divide the half life(T_1/2) into the time (T).

T/T_1/2 = # of half lives

2. Equation to calculate remaining amount left over after a certain number of half lives have passed.

Amt remaining = (initial amt) (.5)^{n (# of half lives)}

__________________________________________________________________________

Refer to Half Life Lab

__________________________________________________________________________

Examples: Suppose you have 20 grams of sodium-24. Its half-life is 15 hours. How much is left over after 60 hours.

Uranium-238 has a half life of 4.46 x 10⁹ years. How long will it take for 7/8^th of the sample to decay?

You Try!

The half life of radium-222 is 38 s. How many grams of a 12.0 g sample are left after 114 s?

Nuclear Fusion

v Small atoms are _______________________ to form a large atom.

v Occurs in the _____________and _____________

v Generates huge amounts of ____________________

Nuclear Fission

v Large atoms _______________ into smaller atoms

v Generates huge amounts of ___________________.

v Used in ___________________power plants.

v Could result in a _______________________ of fission like the _____________________

Tutorials:

Nuclear Reactions:http://ithacasciencezone.com/chemzone/lessons/11nuclear/dcayquiz.htm

Half Life & Nuclear Reactions: http://www.glencoe.com/qe/science.php?qi=2696\