Average mass of an atom in unified atomic mass units (1 u is 1/12 of the mass of a carbon-12 atom). Accounts for the natural mix of the element’s isotopes.
Number of the vertical column, 1 to 18 in IUPAC numbering. Elements in a group share the same outer-shell layout, so their properties are alike.
Number of the horizontal row. Usually equal to the number of electron shells in the atom; palladium is the exception, with four shells in period 5.
The subshell (s, p, d or f) that receives the last electrons in the usual filling order; it divides the table into four blocks. Real atoms sometimes differ: lanthanum starts the f-block but has no f electrons.
[Xe] 6s² 4f¹⁴ 5d¹⁰ 6p²
How electrons are arranged in subshells. The bracket stands for the previous noble gas; the superscript is the number of electrons in a subshell.
2, 8, 18, 32, 18, 4
Number of electrons in each shell, from the nucleus outwards.
327.5 °C (600.61 K)
Temperature at which the solid turns liquid at standard pressure. Helium, carbon and arsenic do not melt at normal pressure: helium needs about 25 atm, carbon and arsenic turn straight into vapour.
1,749 °C (2,022 K)
Temperature at which the liquid boils at standard pressure. For carbon and arsenic, the temperature at which the solid turns straight into vapour (sublimation).
11.342 g/cm³
Mass of one cubic centimetre of the substance. For gases, at 0 °C and standard pressure.
1.87 Pauling
How strongly an atom pulls electrons towards itself in a chemical bond. On the Pauling scale it runs from 0.79 for caesium to 3.98 for fluorine.
7.417 eV
Energy needed to remove the most loosely bound electron from an atom. The lower it is, the more easily the element gives up an electron, which is typical of metals.
0.357 eV
Energy released when a neutral atom gains an electron. Highest for the halogens. Noble gases, nitrogen and some metals form no stable negative ion.
146 pm
Half the length of a single covalent bond between two atoms of the element. It shows the size of an atom inside a molecule or crystal: 76 pm for carbon, 132 pm for iron.
+4, +2
Charges the atom would have in its compounds if all its bonds were ionic; the main ones are listed.
Lead (Pb) is a chemical element with atomic number 82. It sits in group 14 and period 6 of the periodic table, in the p-block. It is a post-transition metal. At room temperature it is a solid. Its standard atomic weight is 207.2.
Origin of the name
Where the English word lead comes from is unknown. The symbol Pb comes from the Latin plumbum, which also gave the word plumber: the Romans made their water pipes of lead. Lead has been known since antiquity.
Where is lead found?
Lead is mined mainly as galena, a heavy, shiny lead sulfide. A large share of the lead used today is recycled, mostly from old batteries.
What is lead used for?
Most lead goes into the lead-acid batteries of cars. Lead is very dense, so it shields people from X-rays and gamma rays in hospitals and nuclear plants. It is also used in ammunition and in some solders and alloys.
Interesting facts
Lead is a poison that builds up in the body and harms especially the brains of children. That is why it has been removed from petrol, paint and water pipes in most countries.