Page 48 - Curriculum Visions Dynamic Book

P see Phosphorus; Pa see Protactinium Palladium (Pd)
Element 46.This grey–white metal is a light transition metal in the Periodic Table. It does not corrode. It is the least dense and has the lowest melting point of the precious metals, which include platinum. It
is soft and can be shaped unless it is cold worked, when it becomes hard. At room temperature palladium absorbs 900 times its own volume of hydrogen!
Discovery
Discovered by William Hyde Wollaston in England in 1803 in a sample of platinum ore.
Technology
It is used to increase the speed of chemical reactions (it is a catalyst). Because it
does not corrode, palladium goes
into electrical contacts to add
reliability in telephone equipment. Some watch springs are made of palladium. Heated palladium helps purify hydrogen because hydrogen readily passes through it. Palladium is used as an alloy in jewellery.White gold is an alloy of gold decolourised by the addition of palladium that is used in crown dental work.
Geology
Palladium is found as a native metal in the same veins close to ancient volcanoes in which platinum, nickel, and copper appear. It is normally recovered as a by-product of refining these other metals.
Biology
Palladium is not found in living things.
Key facts...
Name: palladium
Symbol: Pd
Atomic number: 46
Atomic weight: 106.4
Position in Periodic Table: transition metal,
group (10) (nickel group); period 5.
Precious metal
State at room temperature: solid Colour: grey-white
Density of solid: 11.97 g/cc
Melting point: 1,552°C
Boiling point: 2,970°C
Origin of name: named after the asteroid
Pallas, which was discovered at about the same time. Pallas Athena was the Greek goddess of wisdom.
Shell pattern of electrons: 2–8–18–18
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