All practice pages/Interatomic theory/Elements
Element 4, an alkaline earth metal
A light, stiff metal that X-rays pass straight through, and one of the more dangerous elements to breathe in as dust.
Period 2, group 2. The other alkaline earth metals are tinted, and every cell opens its own article.
Beryllium has 4 electrons, one for every proton, so the atom carries no charge. Below are the same 4 electrons written two ways.
1s² 2s²
Short form: [He] 2s², where [He] stands for the 2 electrons helium already has.
The simple form counts electrons shell by shell. The orbital form says which subshell each one sits in: s holds 2, p holds 6, d holds 10 and f holds 14.
Beryllium sits in period 2 and has 2 shells. The period number counts the shells.
The outer shell holds 2 electrons. Those are the ones beryllium can lose, gain or share, so they are the ones that decide what it bonds with. For a main-group element the group number gives that count: group 2 means 2.
Two valence electrons, but beryllium is so small that its bonds are more covalent than those of the other alkaline earth metals. In its ionic compounds it is Be²⁺.
Rare in the crust. It comes mainly from bertrandite mined in Utah and from beryl, the mineral whose green and blue gem forms are emerald and aquamarine.
Louis-Nicolas Vauquelin found its oxide in beryl and emerald in 1798, and Friedrich Wöhler and Antoine Bussy each isolated the metal in 1828. It was long called glucinium, from the Greek for sweet, because its salts taste sweet. The name beryllium, from beryl, became official in 1949.
Windows for X-ray tubes and detectors, because X-rays pass through it. Copper-beryllium alloys make springs, electrical contacts and non-sparking tools for oil rigs and mines. It is light and stiff enough for aerospace parts: the 18 mirror segments of the James Webb Space Telescope are gold-coated beryllium.
Breathing beryllium dust or fumes can cause chronic beryllium disease, a lasting lung illness, so machining it needs strict dust control. Never taste its compounds.