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.
[Kr] 4d¹⁰
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, 18
Number of electrons in each shell, from the nucleus outwards.
1,554.9 °C (1,828.05 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.
2,963 °C (3,236 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).
12 g/cm³
Mass of one cubic centimetre of the substance. For gases, at 0 °C and standard pressure.
2.20 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.
8.337 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.
0.562 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.
139 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, +3, +2
Charges the atom would have in its compounds if all its bonds were ionic; the main ones are listed.
Palladium (Pd) is a chemical element with atomic number 46. It sits in group 10 and period 5 of the periodic table, in the d-block. It is a transition metal. At room temperature it is a solid. Its standard atomic weight is 106.42.
Origin of the name
Palladium is named after the asteroid Pallas, discovered in 1802 and itself named after the Greek goddess Pallas Athena. William Hyde Wollaston found the metal in 1803 in platinum ore from South America, and at first he made his discovery known anonymously, without revealing how he had obtained it.
Where is palladium found?
Palladium is found together with platinum and in nickel and copper ores. Most of it comes from Russia and South Africa.
What is palladium used for?
More than half of all palladium goes into the catalytic converters of cars. It is also used in electronics and electrical contacts, in dental alloys and in white gold, and finely divided palladium is an important catalyst for adding hydrogen to other substances.
Interesting facts
At room temperature palladium can soak up to 900 times its own volume of hydrogen. Hydrogen even passes straight through hot palladium, which is used to make extremely pure hydrogen.