Our Concept of the Chemical Element Modified by Study of Radio-Active Change. ... IF a chemist were to purify lead from silver, and found on re-examining the lead that silver were present, ...

The quantity of thorium lead per gram of thorium is 0.0062, and this, divided by the rate at which the lead is being produced, 4.72 x l^—11 grams of lead per gram of thorium per year, gives the ...

For example, Lead is a chemical element with the symbol Pb (from the Latin for lead, plumbum).W stands for tungsten (from the word wolfram) and Na stands for sodium (from the word natrium).

Since Mendeleev's time, scientists have discovered new elements, expanding the periodic table. The most recent additions include nihonium, moscovium, tennessine, and oganesson, which were officially ...