Determine the number of protons and the number of neutrons in each isotope. a. 40 19K b. 226 88Ra c. 99 43Tc d. 33 15P

Video transcript

Welcome back. Everyone were asked how many neutrons and protons are in the phosphorus, isotope phosphorus? 35. Let's take a closer look at the symbol we have the number 35 in the left hand exponents, which we should recognize as our mass number or atomic mass. And recall that this number is calculated as the sum of the number of protons and number of neutrons in our atom. But let's recall that protons are actually represented by the symbol Z. Next, we notice the number 15 left hand subscript recall that this number represents our atomic number and is calculated from taking We're from looking at the periodic table and seeing that in group five, a phosphorus has the number 15 over it. And recall that our atomic number is represented also as a symbol Z. And so we can say that our number of protons slash symbol Z is equal to also 15. Now, a note that we want to make is that in neutral atoms only. So in Adam without a charge, our number of protons are equal to the number of electrons. And in this case, we have an isotope of phosphorus which is uncharged there's no charge in our symbol. And so we can say we also have 15 electrons, right. So, so far, we've determined one answer being that we have 15 protons. We need our number of neutrons still though. So because we know that our mass number is the sum of protons plus neutrons, we can write out an equation saying that 35 is equal to 15 plus our number of neutrons. And so two sulfur N we would take minus 15. That's right, that meter -15 from both sides. And so we can say that N is equal to a value of 20. And so we have 20 neutrons in our atom of phosphorus. 35. So what's highlighted in yellow are our two final answers corresponding to choice a in the multiple choice? Thanks for watching and I'll see everyone in the next video.