Groups of exceptions: Transition metals

What defines a transition metal?

Transition metals reside between the primary groups II and III in the periodic table.

These elements refuse to obey the octet rule. Instead, they require a more sophisticated approach.

metals
high melting point, except for Hg, mercury, quicksilver (elohopea)
form ions of varying positive charges
beyond the octet rule
make for colourful compounds with similar formulae
- yellow K2CrO4, potassium chromate
- red K2Cr2O7, potassium dichromate

Fe, iron (rauta)

Iron powder.

Iron oxides, or rusts of iron, have a distictive red colour. This phenomenon causes blood appear red.

Ni, nickel (nikkeli)

Swiss coins of pure nickel from the 20th century. Nickel is known to cause allergic reactions if the susceptibility runs in the family.

Cu, copper (kupari)

Brass (messinki) is an alloy of copper and zinc. Copper has a reddish-orange color as seen on the right.

Copper can be made to react with H2SO4, sulfuric acid to form CuSO4, copper sulfate

Zn, zinc (sinkki)

Brass (messinki) is an alloy of copper and zinc. Zinc has a grey color as seen on the right.

Ag, silver (hopea)

Cd, cadmium (kadmium)

Cadmium has a blue hue, as opposed to aluminium and silver.

Pt, platinum (platina)

Au, gold (kulta)

Hg, mercury, quicksilver (elohopea)

Liquid mercury. The relatively high surface density keeps the droplet thick.

Felt hat maker, 1938 (8867471917).jpg

The toxicity of mercury was not known in the beginning of the 20th century. Here you can see a felt hat maker from 1938, surrounded by toxic fumes yet without any protective gear. Read an article and then another by the National Institute for Occupational Safety and Health.