One isotope of sodium has 11 protons and 7 neutrons. What is t...

Question

One isotope of sodium has 11 protons and 7 neutrons. What is the mass number of this isotope?

Accepted Answer

Hey everyone in this example, we need to answer the questions below. So we have a four part question where in part one we need to identify the subatomic particles in 10-1, So this is an isotope of 10. We want to recall that subatomic particles is referring to a number of protons are number of electrons and our number of neutrons in our isotope. So in order to begin this first part of the question, we want to write the chemical symbol that we know so far. So we know we have the adam tin. We know that it's specifically acadian of tin because they give us the two roman numeral corresponding to the two plus Catalan of tin. And we know the mass number which is given as 121 in the isotope name. And so we call that the mass number is written in the left hand superscript of our chemical symbol for 10. So we also want to recall that there's another component of our chemical symbol, which is our atomic number. So when we find 10 in Group four A on the periodic table, we see that it corresponds to atomic number 50 on the periodic table. And so recall that the atomic number tells us our number of protons in our atom and this would be equal to our number of electrons as well if this atom were neutral. But because we have an ion of two plus, this would only tell us or we would have to calculate our number of electrons. So right now we know that our number of protons is equal to our atomic number, which is 50 not to find our number of electrons Again, we're going to calculate that by taking our original 50 and a neutral atom. But because we have a two plus charge, recall that the canyon too plus charge means we lose Two electrons based on that charge. And that leaves us with 48 electrons for our isotope 1, 21. So so far we found our number of protons and our number of electrons to answer part one. And our last step is to find our number of neutrons. So we want to recall that the given mass number in the left hand superscript is describing our or is found from taking our number of protons and adding it to our number of neutrons. And so we can find our number of neutrons using the information from our mass number. So in order to do so we would take Our mass number which we know is given as 121 and we're going to set that equal to our number of protons, which we determined to be 50 from our atomic number. And we know that that is added to X or a number of neutrons. And so to find our value for X, we would say that X is equal to 1 21 minus 50. And so this would give us an X value equal to 71. And so we know that our number of neutrons is equal to 71 neutrons. So this is going to be our third answer for part one of the question. Moving onto part two, we need to write the symbol of the isotope in the previous question. And so we actually already did so, but we can do that again, so that it's clear we have the chemical symbol which should be 1 20. Oops, that should be a pen. So we have the symbol which should be 1 21 describing our mass number. We have the atomic number 50 which corresponds to the adam 10 and then we have the two plus Catalan charge. So this would be our final answer for part B of the question. So for part C, it says identify the mass number of palladium that has 51 neutrons. So to write out the chemical symbol, we would have palladium we recall is pd on our periodic tables. It's in the transition metal section of our periodic tables and we're told that it has neutrons. When we find palladium on the periodic table, we see that it corresponds to atomic number 46. So we can actually fill that in in our chemical symbol in the left hand subscript, which is where the atomic number always goes. Now recall that the atomic number is describing our number of protons. And so we can say that because we know the atomic number is 46. Therefore we have 46 protons in our atom of palladium. And so we need to find the mass number. So recall that our mass number is written in the left hand superscript and is described by our number of protons plus our number of neutrons. So to find our mass number, We're going to find that by taking our 46 protons and we're going to add that to our given 51 neutrons. And so adding this sum up gives us a total of 97. And so this would interpret our mass number to be a value of 97. So we would fill that in in the left hand superscript of our chemical symbol. And so we have identified that the mass number Is going to be equal to a value of 97 for palladium with 51 neutrons. So this is definitely an isotope of palladium because when we see palladium on the periodic table, we see that it corresponds to the mass number 106, which is definitely a lot higher than 97. So we have an isotope because we have a different number of neutrons in are given example. See moving on to anti choice or sorry example, d it says, identify the sorry, identify the neutral element that could have an isotope with a mass of 52 neutrons. So we're going to use the information given. And because they give us our mass number, we want to recall that our mass number is described by our number of protons plus our number of neutrons. And because they give us our mass number as 52 we would have 52 is equal to P r number of P plus r number of neutrons given us neutrons. And so what we're going to do is subtract 28 from both sides. So this gives us our number of protons equal to A value of 24. And so we want to recall better number of protons corresponds to our atomic number On the periodic table. And so because we know that we have 24 protons, we find atomic number 24 on the periodic table and we see that it corresponds to the atom chromium. And so we would identify that the neutral element with the mass number 52 and 28 neutrons would be chromium because we have found the number of protons corresponding to our atomic number 24. So this completes this example. If you have any questions, please leave them down below. And I will see everyone in the next practice video

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One isotope of sodium has 11 protons and 7 neutrons. What is the mass number of this isotope?

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