Mod H, U4, Les 3 Nucear Reactions

Question 1

What is a nuclear reaction?

Answer 1

A change that affects the nucleus of an atom.

Question 2

How do nuclear reactions differ from chemical reactions?

Answer 2

1. Nuclear: changes mass fo atoms slightly, changing them into energy that is released during reactions. (Does not occur in chemical reactions)
2. Changes the nucleus of atoms. (Chemical reactions don’t) example: can decrease # of protons to change beryllium into lithium)

Question 3

What does the formula E=mc2 mean?

Answer 3

Energy equals mass times the speed of light squared

Question 4

What are isotopes?

Answer 4

Atoms with the same # of protons, but different # of neutrons. (They also have different masses) example lithium-6 or lithium-7 (see p. 243

Question 5

What is radioactive decay?

Answer 5

A nuclear reaction in which an unstable nucleus can give off energy and sometimes particles.

Question 6

What is nuclear radiation?

Answer 6

The term used to describe the particles and energy given off during radioactive decay

Question 7

What are the 3 types of radioactive decay?

Answer 7

Alpha decay, beta decay, and gamma decay

Question 8

Explain Alpha decay.

Answer 8

The release of an alpha particle and energy from a radioactive nucleus. (Alpha particles are made up of 2 protons and 2 neutrons with a charge of 2+). It also reduces the # of protons in the nucleus so it makes a different element.

Question 9

Explain Beta decay.

Answer 9

A release of a beta particle and energy. (2 types of particles are positrons and electrons and both have a mass of almost zero)
Positron charge = 1+
Electron charge = 1-

Question 10

What are gamma rays?

Answer 10

High energy radiation with no mass and no charge

Question 11

Explain gamma decay

Answer 11

When gamma rays are released. It does not change # of particles in nucleus, does not form different elements of isotopes

Question 12

What are 2 effects of too much exposure to radiation?

Answer 12

Radiation sickness (vomiting, hair falling out, fatigue)
Increase cancer risk

Question 13

What are some examples of how scientists are using radioactive decay in our society?

Answer 13

-kill bacteria, find leaks in pipes, determine age in fossils (carbon), find and treat disease, fight cancer

Question 14

What is nuclear fission?

Answer 14

A nuclear reaction in which a large, unstable nucleus breaks into 2 smaller nuclei, and releases neutrons. (It changes the nucleus of the atom that breaks apart)

Question 15

In a fission reaction, the total mass of the end products is less than the mass before the fission reaction began. Why?

Answer 15

The missing mass was transformed to energy

Question 16

What fuel is used to power nuclear power plants?

Answer 16

Uranium-235

Question 17

What is a nuclear chain reaction.Explain what happens using Uranium 235.

Answer 17

a continuous series of fission reactions:
A. Neutrons are released, uranium nucleus splits
B. Other nuclei are hit and split too
C. Process happens over and over, energy is released
*This can be controlled like in a power plant or uncontrolled like in a nuclear bomb

Question 18

Note: see p. 250 to see how an energy power plant controls fission reactions to make electricity.

Answer 18

.

Question 19

What are the disadvantages or using nuclear energy?

Answer 19

When accidents occur: 1. Large amounts of radioactive materials can be released into the atmosphere 2. Radioactive materials can contaminate the environment. (Land and water) 3. Living things can be harmed or can die 4. Uranium is a non-renewable resource. 5 radioactive waste must be stored safely

Question 20

What are the advantages of using nuclear energy?

Answer 20

1. Makes large amounts of energy using small amounts of fuel.
2. Cost cheaper to make electricity than using fossil fuels
3. Does not pollute air or greenhouse gasses while in production
4. There are few accidents because of very high standards

Question 21

What is nuclear fusion?

Answer 21

Uses energy given off by the sun. In this process, the nuclei fo small atoms combine to form a new, more massive nucleus. This happens under extremely high temperatures and pressure which brings them together.

Question 22

What are the products (what is made) during nuclear fusion? See p. 252

Answer 22

Helium nucleus, beta particles, energy from hydrogen nuclei