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.
Hydrogen is a chemical element with symbol H and atomic number 1. Classified as a nonmetal, hydrogen is a gas at room temperature.
With a standard atomic weight of 1.008, hydrogen is the lightest element in the periodic table. Hydrogen is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass.
Hydrogen is estimated to make up more than 90% of all the atoms three quarters of the mass of the universe! This element is found in the stars, and plays an important part in powering the universe through both the proton-proton reaction and carbon-nitrogen cycle. Stellar hydrogen fusion processes release massive amounts of energy by combining hydrogens to form helium.
Hydrogen is the primary component of Jupiter and the other gas giant planets. At some depth in the planet’s interior the pressure is so great that solid molecular hydrogen is converted to solid metallic hydrogen.
In 1973, a group of Russian experimenters may have produced metallic hydrogen at a pressure of 2.8 Mbar. At the transition the density changed from 1.08 to 1.3 g/cm3. Earlier, in 1972, at Livermore, California, a group also reported on a similar experiment in which they observed a pressure-volume point centered at 2 Mbar. Predictions say that metallic hydrogen may be metastable; others have predicted it would be a superconductor at room temperature.