Chemistry
posted by Haile on .
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
_{78}^{196}Pt 
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.