What are Isotopes | Properties of Matter | Infozilla | Chemistry | FuseSchool
Channel: Infozilla
Date: 2020-04-20

What are Isotopes? Find out in this video from the Properties of Matter chapter.


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In a previous video we learnt about Isotopes.
Here are a few more examples.


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There are two isotopic forms of Chlorine:
Chlorine 35 and Chlorine 37. Remember isotopes


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have the SAME number of protons,
but a different number of neutrons. So how


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many neutrons are in each of these isotopic
forms of Chlorine?


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Remember:
Mass Number = Number of Protons + Number of


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Neutrons.
And the number of protons for each isotope forms


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of elements is the same, so we can rearrange
this formula to calculate the number of neutrons


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in each form.
Neutrons = Mass Number - Protons


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When we look at Chlorine on the periodic table
it has an atomic number of 17, therefore it


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has 17 protons.
So Chlorine-35 has a mass of 35.


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Neutrons = Mass Number - Protons
= 35 -17


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= 18
18 neutrons


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So Chlorine-37 has a mass of 37.
Neutrons = Mass Number - Protons


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= 37 -17
= 20


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20 neutrons.
So Chlorine-35 has 18 neutrons and Chlorine


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37 has 20 neutrons.


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Another example of an isotope is Lithium.
Lithium has two stable isotopic forms.


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The atomic number of Lithium is 3, therefore
it has 3 protons.


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The isotopes of Lithium have 3 neutrons and
4 neutrons respectively.


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How do we calculate each of the isotopes mass
number?


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Remember,
Mass Number = Number of Protons + Number of


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Neutrons.
So for one isotopic form the mass number would


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be:
3 + 3 = 6


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So we would have Li-6
And for the other form, the mass number would


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be
3+4 = 7


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So we would have Li- 7

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