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Hi there.
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In this question, we are asked to write the atomic symbol for five different isotopes.
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And so before we get started, let's review a little bit of information.
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First of all, let's talk about the atomic number.
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We can find the atomic number on the periodic table.
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And the atomic number of each element tells you the number of protons in the nucleus of each atom of that type of element.
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So the atomic number is the number of protons, and in a neutral atom, since protons are positive, and electrons are negative, to have a neutral atom, this is also going to be the number of electrons.
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Now, if it's an ion, the number of electrons will differ from the number of protons.
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But all of these we are assuming are just neutral isotopes because it's not telling us otherwise.
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So the atomic number gives us the number of protons and the number of electrons.
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The mass number is the sum of the number of protons plus the number of neutrons.
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So protons plus neutrons give us mass number.
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Okay, armed with this information, let's go ahead and get started.
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In letter a, we have an oxygen atom.
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So we're going to write the o for oxygen.
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Looking at the periodic table, we see that its atomic number is 8, which is right.
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And has a subscript before the symbol.
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And this has 10 neutrons.
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So since it has an atomic number of 8, that means 8 protons.
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And we're told it has 10 neutrons.
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So its mass number is 18 because we just had to add 8 and 10 together to give us 18.
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Okay, so this would be the symbol for this first isotope.
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Remember isotopes are atoms of the same element that have different mass numbers.
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So that's all this means here for isotope is that the mass number might differ from what you're used to for a particular element...