Magnesium (Mg) naturally occurs in three stable isotopes, 24 Mg, 25 Mg, and 26 Mg. There are 19 radioisotopes that have been discovered, ranging from 19 Mg to 40 Mg. The longest-lived radioisotope is 28 Mg with a half-life of 20.915 hours. The lighter isotopes mostly decay to isotopes of sodium while the heavier isotopes decay to isotopes of aluminium. The shortest-lived is 39 Mg with a half-life shorter than 180 nanoseconds, or possibly 40 Mg, with a half-life longer than 170 nanoseconds (the half-life of 19 Mg is unknown). Standard atomic mass: 24.3050(6) u. A chart showing the abundances of the naturally-occurring isotopes of magnesium.
Another large shark, capable of growing to a length of over 16 feet, or 5 meters, the Tiger Shark can be found in the Caribbean and other warm waters around the world. They can have a blue to light green colour, combined with a white or light yellow belly.
Sand sharks, also known as sand tiger sharks, grey nurse sharks or ragged tooth sharks, are mackerel sharks of the family Odontaspididae. They are found worldwide in temperate and tropical waters. The three species are in two genera.