1. What is hydronium?
2. Does it create an acid or base?
3. What is hydroxide
4. Does it create an acid or a base
5. A solution has a pH of 3. What is its concentration of H + ?
6. A solution has a pH of 6. What is its concentration of H + ?
7. A solution has a pH of 8. What is its concentration of H + ?

1. What is radioactivity?
2. What are the three types of radioactive decay?
3. What is an alpha particle?
4. What is a beta particle?
5. What is a gamma particle?
6.
226
88
Ra  222
86
Rn + 4
2
He Name this type of decay.
7.
14
6
8.
12
5
C  14
7
N + 0
-1
B  12
6
C + A e Name this type of decay.
Z
X Identify A, Z and X and this type of reaction

1. What is radioactivity?
2. What are the three types of radioactive decay?
3. What is an alpha particle?
4. What is a beta particle?
5. What is a gamma particle?

1. What is the strong nuclear force?
2. What is nuclear fission?
3. What is a chain reaction?
4. What is released when a neutron splits an atomic nucleus?
5. Name three common uses of radiation.
6. The formula E=mc 2 was developed by whom?
7. What is critical mass?

Select 5 of the following topics to write a GIST about. Use no more than 40 words to summarize each topic you select:
• Periodic Table
• Bonding
• Chemical Reactions
• Acids and Bases
• Solutions/solubility
• Molarity
• Nuclear Chemistry
• Matter
• The Scientific Method

1. The group will select one member to draw.
2. No member can draw twice until all members have drawn.
3. Each group has 3 minutes to try to guess the drawers word.
4. All words were selected from your textbook.
5. No notes, textbooks or other materials are allowed during the game.
6. Words and numbers may not be used on drawings.
7. The winning team will be awarded 10 extra points on their mid-term exam.

8. Group leaders will choose the first member of their group.
9. The newest group member will select the next member.
10.The group guessing their word the fastest in each round will win the round.
11.The group that wins the most number of rounds wins the game.

Nuclear Change

Radioactivity effects our lives daily and in many ways. Technology uses radiation for medicine, energy production and safety devices.

Radioactive materials have unstable nuclei.
They emit particles or energy while seeking stability. These materials undergo change through radioactivity .

These changes occur due to a process called nuclear decay . Through decay an element can change into an isotope of the same element or a different element all together.

Nuclear Radiation – Charged Particles and
• energy that are emitted from the Nuclei

There are three types of nuclear radiation:
Alpha particles
Beta Particles
Gamma Ray

Alpha particles are positively charged and are the most massive of all the other types of nuclear radiation. Alpha particles are made of two protons and two neutrons, the same as a helium atom. Alpha particles can be stopped by a sheet of paper.

238
92
 234
90
4
2

Beta Particles are fast moving electrons. They are able to penetrate matter more deeply that alpha particles. A beta Particle is an electron emitted by an unstable nucleus.
• –Given the Symbol 0
-1 e or 0
-1 b

• Wait a minute…….. A negatively charged particle from the nucleus?
• A neutron decomposes into a proton and an electron. The proton stays in the nucleus and the electron is released.
• Beta Particles can pass through paper, but are stopped by metals

234
90
 234
91
0
-1

Gamma Ray – a penetrating ray of energy emitted by an unstable nucleus.
• Has No Mass
• Has No Charge
• Is a form of Electromagnetic Radiation
• Travel at the Speed of Light
• Often are accompanied by Beta decay.
• Gamma rays have much power and can penetrate 7 cm of lead

234
90
 234
91
0
-1
0
0 g

Radiation Type Symbol Charge Mass Common
Source
Alpha 4
2
He or
4
2 a
2+ 4 Radium
226
Beta 0
-1
11/1836 Carbon
14
Gamma 0
0 g 0 0 Cobalt 60

While it is impossible to predict when any particular nucleus will decay, it is possible to predict how long t will take half the nuclei in a particular sample to decay. This time is known as the samples half-life .

• Amount remaining=Initial Amount(1/2) n
• Where n=the number of half-lives that have passed
Or
• Amount remaining=Initial Amount(1/2) t/T
• Where t is elapsed time and T is duration of the half-life.

Problem:
228 Ac has a half life of 6.13 hours. How much of a 5.0 mg sample would remain after one day?

Solution:
The first step is to determine the number of half lives that have elapsed.
number of half lives = 1 half life/6.13 hours x 1 day x 24 hours/day number of half lives = 3.9 half lives
For each half life, the total amount of the isotope is reduced by half.
Amount remaining = Original amount x 1/2 (number of half lives)
Amount remaining = 5.0 mg x 2 -(3.9)
Amount remaining = 5.0 mg x (.067)
Amount remaining = 0.33 mg

After the first half-life of a sample has passed, half the sample remains unchanged and half has decayed. After the second half-life has passed, half of the remaining radioactive sample has changed (1/2 X 1/2 = 1/4).
Following the next half-life, ½ of the remaining sample will be decayed 1/2 X 1/2 X 1/2 = 1/8).

Radioactive half-lives are different for different elements. Half-lives can vary from fractions of a second to billions of years.

• Hydrogen-3 (tritium)
• Beryllium-10
• Carbon-14
• Silicon-32
• Phosphorus-32
• Potassium-40
• Calcium-42
• Iron-55
• Cobalt-60
• Nickel-59
• Nickel-63
• Selenium-79
• 12 years
• 1 million 600 thousand years
• 5 thousand 700 years
• 500 years
• 14 days
• 1 thousand million years
• 14 thousand years
• 3 years
• 5 years
• 75 thousand years
• 10 years
• 65 thousand years

Page 292, Section One Review (Chapter 9).
Problems 1-7.

In 1939, while trying to create heavy isotopes,
German scientists first split the atom. Nuclei are held together by a special force. Despite being positively charged (protons) they don’t fly apart. This force is called the strong nuclear force .

If the strong nuclear force is stronger than the force of repulsion, the nucleus is stable and does not decay. However, as protons and neutrons are added to a nucleus, it gets less and less stable. If these nuclei become too unstable then they will decay . Nuclei with more than 83 protons are always unstable.

As these nuclei decay, they release energy in the form of radiation. Scientists have learned that by bombarding radioactive elements, like uranium (92 protons) with neutrons, they can split the uranium atom and release this energy from the strong nuclear force.

When a neutron hits an atom and splits it, the atom releases additional neutrons. These neutrons, in turn, split other atoms. This process accelerates as more neutrons are generated and more atoms are split. This process is known as a chain reaction .

Fission produces lots of heat. This heat is used in power plants to heat water into stream that is then used to turn a turbine and generate electricity.

During the process of fission, a small amount of the mass of the nucleus is turned into energy. This reaction is defined by
Einstein’s equation, E=mc 2 .
Small amounts of mass are converted into vast quantities of energy. One kg of mass can be converted into as much energy as 22 million tons of TNT.

In an atomic bomb, two masses of uranium are needed. These two masses are surrounded by an explosive. When the explosive is detonated, the two masses are slammed together and compressed. This compression leads to critical mass . Critical mass means that the atoms are forced close enough together to sustain a chain reaction.

Chapter 9: Section 1 Review-page 292, problems 1-5.