Group 10: the nickel group

Ten electrons, three arrangements

Each atom has ten electrons beyond its noble gas core, but each natural member arranges them differently. Nickel is [Ar] 3d⁸ 4s² and platinum is [Xe] 4f¹⁴ 5d⁹ 6s¹. Palladium is [Kr] 4d¹⁰, making it the only element with no s electrons outside its noble gas core.

In compounds the differences fade. Nickel and palladium are mostly +2, while platinum forms both +2 and +4 compounds. All three can grab hydrogen molecules on their surfaces, loosen the bond and hand the hydrogen atoms on to other molecules, which is what makes them such good catalysts.

Trends down the group

Nickel melts at 1728 K, palladium at 1828.05 K and platinum at 2041.4 K, a gentler rise than in the groups to the left. Density jumps from 8.908 g/cm³ for nickel to 12.023 g/cm³ for palladium and 21.45 g/cm³ for platinum. Electronegativity climbs from 1.91 to 2.2 and 2.28.

The heavier metals are also more noble. Platinum does not tarnish in air and dissolves only in hot aqua regia. Nickel stands apart in another way: it is ferromagnetic like iron and cobalt, while palladium and platinum are not.

Where you meet group 10

Nickel is in stainless steel, rechargeable batteries and coins, although the American five-cent coin called the nickel is actually three-quarters copper. Nickel catalysts add hydrogen to vegetable oils to make them more solid. Palladium and platinum clean exhaust gases in catalytic converters, and palladium can soak up hundreds of times its own volume of hydrogen gas. Platinum is used in jewelry, laboratory electrodes and cisplatin, a widely used cancer drug.

Darmstadtium

Darmstadtium (110) is named after the German city of Darmstadt, where it was first made in 1994. Only a few atoms have ever been produced, so its properties are predicted, not measured.