পর্যায় সারণীর দ্বিতীয় স্থানে অবস্থিত মৌলটির নাম কী ?
Beryllium (Be) is the chemical element with atomic number 4, occurring in the form of <sup>9</sup>Be. At standard temperature and pressure, beryllium is a strong, steel-grey, light-weight, brittle, bivalent alkali earth metal, with a density of 1.85 g·cm<sup>−3</sup>. It also has one of the highest melting points of all the light metals. Beryllium's most common isotope is <sup>9</sup>Be, which contains 4 protons and 5 neutrons. It makes up almost 100% of all naturally occurring beryllium and is its only stable isotope; however other isotopes have been synthesised. In ionic compounds, beryllium loses its two valence electrons to form the cation, Be<sup>2+</sup>.
Beryllium