91影视

Any of a class of rare gases that display high stability and extremely low reaction rates, such as helium, neon, argon, krypton, xenon, and generally radon.

Because most copper ores (Greek chalkos) are oxides or sulphides, and such ores contain quantities of selenium and tellurium, the group VIA elements are referred to as chalcogens.

The alkaline earth metals are named after its oxides, the alkaline earths, which used to be known as beryllia, magnesia, lime, strontia, and baryta. When mixed with water, these oxides become basic (alkaline).

Heat, hydrogen gas, and the equivalent metal hydroxide are produced when alkali metals react with water. The heat generated by this reaction has the potential to ignite the hydrogen or the metal itself, resulting in a fire or explosion.