Transition metals
The A metal that is located in between Group 2 and Group 3 and has brightly coloured compounds. are in the block in the middle of the periodic table, between Groups 2 and 3. They are all metals and include many common metals such as chromium (Cr), iron (Fe), nickel (Ni) and copper (Cu).
The table below compares the physical properties of the transition metals and the alkali metals.
| Physical properties | Group 1 鈥 alkali metals | Groups 2 and 3 鈥 transition metals |
| melting point | low melting point | high melting point (except mercury) |
| density | low density 鈥 Li, Na and K are less dense than water | high density |
| reactivity with water | very reactive with cold water Group 1 metal + water 鈫 metal hydroxide + hydrogen | low reactivity with water some react with steam to form an oxide and hydrogen copper does not even react with steam |
| formation of ions | react to form 1+ ions (e.g. K+) | react to form ions with different charges e.g. iron can form Fe2+ and Fe3+ ions |
| colour of compounds | form white compounds, e.g. sodium chloride is white | form coloured compounds (e.g. copper(II) carbonate is green) |
| Physical properties | melting point |
|---|---|
| Group 1 鈥 alkali metals | low melting point |
| Groups 2 and 3 鈥 transition metals | high melting point (except mercury) |
| Physical properties | density |
|---|---|
| Group 1 鈥 alkali metals | low density 鈥 Li, Na and K are less dense than water |
| Groups 2 and 3 鈥 transition metals | high density |
| Physical properties | reactivity with water |
|---|---|
| Group 1 鈥 alkali metals | very reactive with cold water Group 1 metal + water 鈫 metal hydroxide + hydrogen |
| Groups 2 and 3 鈥 transition metals | low reactivity with water some react with steam to form an oxide and hydrogen copper does not even react with steam |
| Physical properties | formation of ions |
|---|---|
| Group 1 鈥 alkali metals | react to form 1+ ions (e.g. K+) |
| Groups 2 and 3 鈥 transition metals | react to form ions with different charges e.g. iron can form Fe2+ and Fe3+ ions |
| Physical properties | colour of compounds |
|---|---|
| Group 1 鈥 alkali metals | form white compounds, e.g. sodium chloride is white |
| Groups 2 and 3 鈥 transition metals | form coloured compounds (e.g. copper(II) carbonate is green) |
You鈥檒l notice under 鈥榝ormation of ions鈥 that the transition metals react to form ions with different charges. An iron(II) ion has a 2+ charge, and an iron(III) ion has a 3+ charge.
They form coloured compounds:
| Transition metal compound | copper(II) oxide | copper(II) carbonate | hydrated copper(II) sulfate | any copper(II) salt in solution |
| Colour | black solid | green solid | blue crystals | blue solution |
| Transition metal compound | Colour |
|---|---|
| copper(II) oxide | black solid |
| copper(II) carbonate | green solid |
| hydrated copper(II) sulfate | blue crystals |
| any copper(II) salt in solution | blue solution |