All practice pages/Interatomic theory/Elements
Element 40, a transition metal
The metal neutrons pass straight through, which is why it wraps the fuel in nuclear reactors, and the stuff of cubic zirconia gems.
Period 5, group 4. The other transition metals are tinted, and every cell opens its own article.
Zirconium has 40 electrons, one for every proton, so the atom carries no charge. Below are the same 40 electrons written two ways.
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d² 5s²
Short form: [Kr] 4d² 5s², where [Kr] stands for the 36 electrons krypton already has.
That list runs by shell. In the order the subshells fill it reads [Kr] 5s² 4d², because a subshell fills by its energy, not by its shell number.
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. Shell 3 here is 3s² 3p⁶ 3d¹⁰, and 2 + 6 + 10 is 18.
Zirconium sits in period 5 and has 5 shells. The period number counts the shells.
The outer shell holds 2 electrons. Those are the ones zirconium can lose, gain or share, so they are the ones that decide what it bonds with.
Like other transition metals, zirconium loses its outer s electrons, and often some d electrons as well, to form positive ions, and it can form more than one kind.
Mined as zircon (ZrSiO₄) from beach sands, above all in Australia and South Africa. Zircon crystals are among the oldest things on Earth: grains from Western Australia are about 4.4 billion years old.
Martin Heinrich Klaproth identified zirconia in 1789 in a zircon gem from Sri Lanka, and Jöns Jacob Berzelius isolated the metal in 1824. The name comes from the mineral zircon, probably from the Persian zargun, gold-colored.
Most zircon goes into ceramics, tiles and foundry molds. The metal, alloyed as Zircaloy, sheathes the uranium fuel in nuclear reactors because it barely absorbs neutrons and resists corrosion. Zirconium dioxide makes cubic zirconia gems, ceramic knives and dental crowns.