Strontium is an element with atomic symbol Sr, atomic number 38, and atomic weight 87.62.
Strontium atom is an alkaline earth metal atom.
Strontium is a naturally occurring element found in rocks, soil, dust, coal, and oil. Naturally occurring strontium is not radioactive and is either referred to as stable strontium or strontium.
Strontium in the environment exists in four stable isotopes, 84Sr (read as strontium eighty-four), 86Sr, 87Sr, 88Sr. Strontium compounds are used in making ceramics and glass products, pyrotechnics, paint pigments, fluorescent lights, and medicines.
Strontium can also exist as several radioactive isotopes; the most common is 90Sr. 90Sr is formed in nuclear reactors or during the explosion of nuclear weapons.
Radioactive strontium generates beta particles as it decays. One of the radioactive properties of strontium is half-life, or the time it takes for half of the isotope to give off its radiation and change into another substance. The half-life of 90Sr is 29 years.
Nitrogen is the chemical element with the symbol N and atomic number 7.
It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772.
Although Carl Wilhelm Scheele and Henry Cavendish had independently done so at about the same time, Rutherford is generally accorded the credit because his work was published first.
The name nitrogène was suggested by French chemist Jean-Antoine-Claude Chaptal in 1790, when it was found that nitrogen was present in nitric acid and nitrates.
Antoine Lavoisier suggested instead the name azote, from the Greek ἀζωτικός “no life”, as it is an asphyxiant gas; this name is instead used in many languages, such as French, Russian, Romanian and Turkish, and appears in the English names of some nitrogen compounds such as hydrazine, azides and azo compounds.