All practice pages/Interatomic theory/Elements
Element 82, a post-transition metal
A dense, soft metal used since ancient Rome, which gave us the word plumber, and a poison that harms children's brains.
Period 6, group 14. The other post-transition metals are tinted, and every cell opens its own article.
Lead has 82 electrons, one for every proton, so the atom carries no charge. Below are the same 82 electrons written two ways.
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p²
Short form: [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p², where [Xe] stands for the 54 electrons xenon already has.
That list runs by shell. In the order the subshells fill it reads [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p², 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 4 here is 4s² 4p⁶ 4d¹⁰ 4f¹⁴, and 2 + 6 + 10 + 14 is 32.
Lead sits in period 6 and has 6 shells. The period number counts the shells.
The outer shell holds 4 electrons. Those are the ones lead 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 14 means 4.
Four valence electrons, but lead usually gives up only its two 6p electrons to form Pb²⁺, while its two 6s electrons hold on. Chemists call this the inert pair effect.
Mined mostly as galena (PbS) in China, Australia, Peru and the United States, though more lead now comes from recycled batteries than from mines. It is the stable end point of the decay of uranium and thorium.
Known since ancient times; the Romans used it for water pipes, cooking pots and coins. The name is Old English, and the symbol Pb comes from its Latin name plumbum, the source of the word plumber.
Lead-acid batteries for cars, trucks and backup power use about 80% of it. Lead also shields against X-rays and radiation and goes into ammunition, weights and roofing. It was once used widely in gasoline, paint, solder and water pipes, uses that are now banned or restricted.
A cumulative poison that damages the brain and nervous system, especially in children, even at low levels. Lead leaching from old water pipes caused the Flint water crisis in Michigan in 2014.