Section 1: What is Radioactivity?
description
Transcript of Section 1: What is Radioactivity?
![Page 1: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/1.jpg)
Section 1Nuclear Changes
Section 1: What is Radioactivity?
Preview• Key Ideas• Bellringer• Nuclear Radiation• Nuclear Decay• Math Skills• Radioactive Decay Rates
![Page 2: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/2.jpg)
Section 1Nuclear Changes
Key Ideas
〉What happens when an element undergoes radioactive decay?
〉How does radiation affect the nucleus of an unstable isotope?
〉How do scientists predict when an atom will undergo radioactive decay?
![Page 3: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/3.jpg)
Section 1Nuclear Changes
Bellringer
Before studying about nuclear chemistry, answer the following items to refresh your memory about the structure of the nucleus.
1. Label the diagram below.
![Page 4: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/4.jpg)
Section 1Nuclear Changes
Bellringer, continued
2. Complete the table below to indicate how many protons and neutrons are in the nuclei of each atom.
![Page 5: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/5.jpg)
Section 1Nuclear Changes
SPS3.a&b Differentiate between alpha and beta particles and gamma radiation and between fission and fusion.
![Page 6: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/6.jpg)
Section 1Nuclear Changes
EQ: What are the components of radioactivity and what are the types of nuclear reactions?
![Page 7: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/7.jpg)
Section 1Nuclear Changes
Nuclear Radiation
What happens when an element undergoes radioactive decay?
![Page 8: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/8.jpg)
Section 1Nuclear Changes
10-1-1 Nuclear Radiation
After radioactive decay, the element changes into a different isotope of the same element or into an entirely different element.
![Page 9: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/9.jpg)
Section 1Nuclear Changes
10-1-2 Nuclear Radiation
• radioactive decay: the disintegration of an unstable atomic nucleus into one or more different nuclides
![Page 10: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/10.jpg)
Section 1Nuclear Changes
10-1-3 Nuclear Radiation, continued
• nuclear radiation: the particles that are released from the nucleus during radioactive decay
![Page 11: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/11.jpg)
Section 1Nuclear Changes
10-1-4 Nuclear Radiation, continued
nuclear radiation can contain
•alpha particles
•beta particles
•gamma rays
•neutrons
![Page 12: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/12.jpg)
Section 1Nuclear Changes
10-1-5 Types of Nuclear Radiation
![Page 13: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/13.jpg)
Section 1Nuclear Changes
10-1-6 Nuclear Radiation, continued
• alpha particle: a positively charged particle that consists of two protons and two neutrons and that is emitted from the nucleus during radioactive decay
![Page 14: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/14.jpg)
Section 1Nuclear Changes
10-1-7 Nuclear Radiation, continued
•beta particle: an electron or positron that is emitted from a neutron in a nucleus during radioactive decay
![Page 15: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/15.jpg)
Section 1Nuclear Changes
10-1-8 Nuclear Radiation, continued•Gamma rays are high-energy electromagnetic radiation.
![Page 16: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/16.jpg)
Section 1Nuclear Changes
10-1-9 Nuclear Radiation, continued
•gamma ray: a high-energy photon emitted by a nucleus during fission and radioactive decay
![Page 17: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/17.jpg)
Section 1Nuclear Changes
10-1-10 Nuclear Radiation, continued
•Neutron emission consists of matter that is emitted from an unstable nucleus.
![Page 18: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/18.jpg)
Section 1Nuclear Changes
10-1-11 Nuclear Radiation, continued
•Neutrons are able to travel farther through matter than either alpha or beta particles.
![Page 19: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/19.jpg)
Section 1Nuclear Changes
Nuclear Decay
How does radiation affect the nucleus of an unstable isotope?
![Page 20: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/20.jpg)
Section 1Nuclear Changes
10-1-12 Nuclear Decay
Anytime that an unstable nucleus emits alpha or beta particles, the number of protons or neutrons changes.
![Page 21: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/21.jpg)
Section 1Nuclear Changes
10-1-13 Nuclear Decay
• Nuclear-decay equations are similar to those used for chemical reactions.
![Page 22: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/22.jpg)
Section 1Nuclear Changes
10-1-14 Nuclear Decay, continued
• Gamma decay changes the energy of the nucleus, but not the atomic number or the atomic mass of the element.
![Page 23: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/23.jpg)
Section 1Nuclear Changes
10-1-15 Nuclear Decay, continued
• The atomic number changes during beta decay, but not the mass number.
![Page 24: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/24.jpg)
Section 1Nuclear Changes
10-1-16 Nuclear Decay, continued
In beta decay the atomic number of the product nucleus increases by 1 and the atom changes to a different element.
![Page 25: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/25.jpg)
Section 1Nuclear Changes
10-1-17 Nuclear Decay, continued
• A beta decay process occurs when carbon-14 decays to nitrogen-14 by emitting a beta particle.
![Page 26: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/26.jpg)
Section 1Nuclear Changes
10-1-18 Nuclear Decay, continued• Both atomic mass and number
change in alpha decay.–The atomic mass decrease by 4.–The atomic number decreases
by 2.
![Page 27: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/27.jpg)
Section 1Nuclear Changes
Visual Concept: Alpha, Beta, and Gamma Radiation
![Page 28: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/28.jpg)
Section 1Nuclear Changes
Math Skills
Nuclear Decay Actinium-217 decays by releasing an alpha particle. Write the equation for this decay process, and determine which element is formed.
1. Write down the equation with the original element on the left side and the products on the right side.
X = unknown product; A = unknown mass;
Z = unknown atomic number
217 489 2Ac HeA
Z X
![Page 29: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/29.jpg)
Section 1Nuclear Changes
Math Skills, continued2. Write math equations for the atomic and mass numbers.
217 = A + 4 89 = Z + 23. Rearrange the equations.
A = 217 – 4 Z = 89 – 2
A = 213 Z = 874. Rewrite the equation with all nuclei represented.
The unknown decay product has an atomic number of 87, which is francium.
217 213 489 87 2 Ac Fr He
![Page 30: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/30.jpg)
Section 1Nuclear Changes
Radioactive Decay Rates
How do scientists predict when an atom will undergo radioactive decay?
![Page 31: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/31.jpg)
Section 1Nuclear Changes
10-1-19 Radioactive Decay Rates
• half-life: the time required for half of a sample of a radioactive isotope to break down by radioactive decay to form a daughter isotope
![Page 32: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/32.jpg)
Section 1Nuclear Changes
10-1-20 Radioactive Decay Rates, continued
Scientists can also use half-life to predict how old an object is.
![Page 33: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/33.jpg)
Section 1Nuclear Changes
Math Skills
Half-Life Radium-226 has a half-life of 1,599 years. How long will seven-eighths of a sample of radium-226 take to decay?
1. List the given and unknown values.
Given: half-life = 1,599 years
fraction of sample decayed = 7/8
Unknown:fraction of sample remaining = ?
total time of decay = ?
![Page 34: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/34.jpg)
Section 1Nuclear Changes
Math Skills, continued2. Calculate the fraction of radioactive sample remaining.
3. Determine how much of the sample is remaining after each half-life.
fraction of sample remaining = 1 – fraction decayed
7 1fraction of sample remaining = 1
8 8
1amount of sample remaining after one half-life =
21 1 1
amount of sample remaining after two half-lives = 2 2 4
1 1 1 1amount of sample remaining after three half-lives =
2 2 2 8
![Page 35: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/35.jpg)
Section 1Nuclear Changes
Math Skills, continued
4. Multiply the number of half-lives by the time for each half-life to calculate the total time required for the radioactive decay.
Each half-life lasts 1,599 years.
1,599 y
total decay time = 3 half-lives 4,797 yhalf-life
![Page 36: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/36.jpg)
Section 1Nuclear Changes
Radioactive Decay Rates, continued• Radioactive decay is exponential decay.
• decay curve: a graph of the number of radioactive parent nuclei remaining in a sample as a function of time
• Carbon-14 is used to date materials.
– The ratio of carbon-14 to carbon-12 decreases with time in a nonliving organism.
– By measuring this ratio and comparing it with the ratio in a living plant or animal, scientists can estimate how long ago the once-living organism died.
![Page 37: Section 1: What is Radioactivity?](https://reader036.fdocuments.net/reader036/viewer/2022062422/568139d9550346895da18cfd/html5/thumbnails/37.jpg)
Section 1Nuclear Changes
Radioactive Decay of Carbon-14