Radioactive decay mechanisms and radioisotopes
-
Upload
james-rush -
Category
Documents
-
view
73 -
download
1
description
Transcript of Radioactive decay mechanisms and radioisotopes
An alpha particle is really four particleswhich are ejected from the nucleusof an unstable atom.
An alpha particle is two protons andtwo neutrons.
previous next smart
What happens when atoms of emit alpha particles?
Notice that it is impossible to predict which atoms will decay but we can seethat the rate ofdecay slows down with time.
We will now lookdeeper inside the atom to see what is happening to the nucleus.
23793 Np
This is a model to simulate how ALPHA particles are emitted from a radioactive isotope of NEPTUNIUM.
previous next smart
The nucleus
loses 2 protonsand 2 neutrons which we call an alpha particle
Taking a closer look inside the NEPTUNIUM atom
previous next smart
Before After
Np Pa237
93 91 +Neptunium Palladium alpha
+
previous next smart
Fill in the missing numbersto complete the equation
A beta particle is simply a fast movingelectron.
This particle is also ejected fromthe nucleus of an unstable atom but the way this happens is more complicated thanalpha emission.
previous next smart
What happens when atoms emit beta particles?
Notice that it is impossible to predict whichatoms will decay but we can seethat the rateof decay slowsdown with time.
233Pa91
We will now lookdeeper inside the atom to see what is happening to the nucleus.
This is a model to simulate how BETA particles are emitted from a radioactive isotope of PALLADIUM.
previous next smart
emits a betaparticle whena neutronchanges intoa proton andan electron
Taking a closer look inside the PALLADIUM atom
The nucleus
previous next smart
Before After
Pa U233
91 +0
-1
Palladium Uranium Beta
B
+
previous next smart
Fill in the missing numbersto balance the equation
Gamma rays are really electromagneticrays which are given out by the nucleusof unstable atoms. You will not need to know how this affectsthe nucleus of an unstable atom.
previous next smart
145
144
143
142
141
140
139
138
137
13687 88 89 90 91 92 93 94
Number ofneutrons
Number ofprotons
X
Np237
Pa233
U233
Th229
Neptunium-237 ( Np)is a radioactive element.The graph shows the numbers of neutrons andprotons in the nuclei ofthe elements formed when Np decays.
237
237
previous next smart
145
144
143
142
141
140
139
138
137
13687 88 89 90 91 92 93 94
Number ofneutrons
Number of protons
X
Np237
Pa233
U233
Th229
(a)Use the periodic tableto identify element X.
(b) Why are Pa and U considered to be different elements?
233
233
(c) What type of radiationis released when Npdecays to form Pa?
237
233
(d) What change takes placein the nucleus when Pachanges into U?
233
233
previous next smart
145
144
143
142
141
140
139
138
137
13687 88 89 90 91 92 93 94
Number ofneutrons
Number ofprotons
X
Np237
Pa233
U233
Th229
(a)Use the periodic tableto identify element X.
previous next smart
145
144
143
142
141
140
139
138
137
13687 88 89 90 91 92 93 94
Number ofneutrons
Number ofprotons
X
Np237
Pa233
U233
Th229
(b) Why are Pa and U considered to be different elements?
233
233
Pa has 91 protons
U has 92 protons
Different protonnumber meansdifferent element.
previous next smart
145
144
143
142
141
140
139
138
137
13687 88 89 90 91 92 93 94
Number ofneutrons
Number ofprotons
Np237
Pa233
(c) What type of radiationis released when Npdecays to form Pa?
237
233
The nucleus of Neptuniumhas lost 2 neutrons
and 2 protons.
Alpha particle
NeptuniumnucleusPa nucleus
previous next smart
145
144
143
142
141
140
139
138
137
13687 88 89 90 91 92 93 94
Number ofneutrons
Number ofprotons
Np237
Pa233
U233
(d) What change takes placein the nucleus when Pachanges into U?233
233
The neutron number decreases by one
but the proton numberincreases by one
A neutron changes into a proton andan electron
previous next smart
previous next smart
An isotope is an atom which has the same number of protons but a different number of neutrons
The underlined phrases score the marks---so learn this definition off by heart
You should know what an isotope is
What a radio-isotope is and
give some examples.
previous next smart
H H H
previous next smart
Write in the missing numbers(the bottom one is the number of protons)(the top one is the protons and neutrons)
C CN
Carbon-12 is stable but Carbon-14 is unstable (a radio-isotope). Carbon-14 emits a beta particle and decays to become nitrogen
previous next smart
Count the particlesin these nuclei afterthe beta particle is emitted and fill in thenumbers
C12
6
14
7 N
Carbon-12 is stable but Carbon-14 is unstable (a radio-isotope). Carbon-14 emits a beta particle and decays to become nitrogen
previous next smart
answers