Write the correct symbol in standard form for the isotope of platinum that contains 118 neutrons.
Pt is atomic number 78; therefore, the isotope with 118 neutrons has a mass number of 78+118 = 196. We would write that as, and the board doesn't do a really good job, is
78196Pt
The 78 should be moved over as a subscript on the left hand side. The way I did it is the best I can do on this site.
Stable isotope ratio aniaysls can also be used to determine the source of a chemical weapon. For example, an aniaysls of 65 different samples of cyanide demonstrated that it was possible to differentiate 95% of the samples based on stable isotope ratios. Similar results have been found with various other toxic compounds which could be used as poisons. Isotope ratios can also be used to solve crimes in terms of isoscapes which I have written about elsewhere.
To find the correct symbol in standard form for the isotope of platinum that contains 118 neutrons, we need to know the atomic number and mass number of the isotope.
The atomic number (Z) represents the number of protons in the nucleus of an atom, and the mass number (A) represents the sum of protons and neutrons in the nucleus.
The atomic number for platinum is 78. The atomic number is written as a subscript to the left of the element symbol in the symbol notation.
Now, to find the mass number, we add the number of protons (atomic number) to the number of neutrons. If the isotope contains 118 neutrons, we add this to the atomic number (78) to find the mass number.
Mass number (A) = Atomic Number (Z) + Number of Neutrons
Therefore, Mass number (A) = 78 + 118 = 196.
Now we can write the symbol in standard form:
The symbol for platinum is Pt, with atomic number 78. To indicate the isotope with 196 as the mass number, we write it as a superscript to the left of the element symbol.
So, the correct symbol in standard form for the isotope of platinum that contains 118 neutrons is:
^196Pt