Video: Understanding Element Symbols

A nitrogen atom has the chemical symbol nitrogen-14. How many protons does the nitrogen atom have? How many neutrons does the nitrogen atom have?

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Video Transcript

A nitrogen atom has the chemical symbol nitrogen-14. How many protons does the nitrogen atom have? How many neutrons does the nitrogen atom have?

To figure out the answer to these questions, letโ€™s take a closer look at this chemical symbol. In this symbol, the capital ๐‘ is the shorthand abbreviation for the element nitrogen. Then the number to the lower left of that symbol, in this case seven, is called the atomic number. This number represents the number of protons in the nucleus of the particular element weโ€™re talking about, in this case nitrogen.

If we represented the nucleus of this nitrogen atom by this space, then the atomic number of seven means that there are one, two, three, four, five, six, seven protons in this nucleus. And that gives us the answer to our first question. The number of protons this nitrogen atom has is seven.

Next, we want to know how many neutrons the atom has. And to figure that out, weโ€™ll look at this number in the upper left. This is known as the mass number of this atom. Itโ€™s equal to the number of protons plus the number of neutrons in the atom.

Now if the mass number is equal to the number of protons โ€” we can call it ๐‘ sub ๐‘ โ€” plus the number of neutrons โ€” weโ€™ll call it ๐‘ sub ๐‘› โ€” then we can see that if we subtract from that number, the number of protons, then what weโ€™ll get overall is the number of neutrons.

We can see from the chemical symbol of this nitrogen atom that this number is 14 and that this number is seven. When we perform this subtraction, we get a result of seven. And thatโ€™s equal to ๐‘ sub ๐‘›, the number of neutrons in the atom. So if we were to draw in neutrons in green, then we will complete our picture of the nucleus by drawing seven of those in place. And that answers our second question. The number of neutrons that this nitrogen atom has is seven.

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