The atomic masses of nitrogen-14, titanium-48, and xenon-129 are 13.999234 amu, 47.935878 amu, and 128.904779 amu, respectively. For each isotope, calculate (a) the nuclear mass.

Video transcript

Welcome back everyone in this example, we have oxygen 15. Vanadium 51 bismuth 209. With the atomic masses of 15 point oh 3605 A. M. U. S. 50.94 39 64 A. M. U. S. And 208 98 30 99 A. M. Us respectively. What is the nuclear mass of each isotope? Were given the mass of an electron as 5.4857 and nine times 10 to the negative fourth power am use So we want to recall that to calculate nuclear mass. We're going to take our atomic mass subtracted from our mass of electrons for the isotope. So beginning with our first isotope listed in the prompt as oxygen recalled that the number given in the name of the isotope is the mass number. Where we want to recall that our mass number is described as our some of our protons to neutrons recognized that on our periodic table, oxygen found in Group six A. Has the atomic number eight. And recall that our atomic number tells us our number of protons meaning we would have eight protons. And because this is a neutral atom of oxygen, this also corresponds to eight electrons. So to calculate our nuclear mass for oxygen we begin with its atomic mass given in the prompt as 15.3065. Am use subtracting it from the mass of the electron. Where we determined that oxygen here because it has atomic number eight should have eight electrons. Which we're multiplying by the mass of the electron given in the prompt as 5.485799 times 10 to the negative fourth power AM use. And this is going to result in a nuclear mass equal to a value of 14.998676 am use. So this would be our first answer as our nuclear mass of our isotope oxygen. 15. So let's move on to our next isotope given in the prompt. As vanadium 51. Recall that on our periodic table, vanadium corresponds to atomic number 23 meaning we would have 23 protons and 23 electrons. Since this is a neutral atom of vanadium. So calculating its nuclear mass, We would begin with its atomic mass given in the prompt as 50 39 64. Am use subtracting from the 23 electrons present in vanadium which we multiply by the mass of the electron given in the prompt as 5.485799 times 10 to the negative fourth power A. M. Use. So moving on in our calculation we would get a nuclear mass equal to a value of 50.93 13 47 A. M. Use. So this is our second answer for our nuclear mass of vanadium 51. So moving forth to our third isotope mentioned in the prompt, we have bismuth 209 represented by B I 209. Recall that when we find bismuth on our periodic table, it corresponds to atomic number 83 corresponding to 83 protons and 83 electrons. Since this is also a neutral atom of bismuth. So now calculating bismuth 209 nuclear mass, we begin with its atomic mass given in the prompt as to uh 8.9 83 99 A. M. Use subtracted from its 83 electrons multiplied by the mass of the electron given in the prompt as 5.485799 times to the negative fourth power negative fourth power am use here. This is going to result in our nuclear mass of business 209 equal to 208 34 8 67 A. M. Use. And this would be our third and final answer as our nuclear mass of 209 bismuth. To complete this example. So each of our isotopes with their associated nuclear masses are highlighted in yellow. This will complete this prompt as our final answers. If you have any questions, leave them down below and I will see everyone in the next practice video