Ga
Gallium
Element 31 · 69.723 u
Gallium is a soft metal with an unusually low melting point that will melt in your hand.
Physical Properties
| Atomic Mass | 69.723 u |
| Density | 5.907 g/cm³ |
| Melting Point | 302.91 K |
| Boiling Point | 2477.0 K |
| Appearance | Silvery-blue metallic |
| State at Room Temp | Solid |
Chemical Properties
| Electronegativity | 1.81 (Pauling) |
| 1st Ionization Energy | 578.8 kJ/mol |
| Electron Affinity | 28.9 kJ/mol |
| Oxidation States | +1, +2, +3 |
Atomic Properties
| Electron Configuration | [Ar] 3d10 4s2 4p1 |
| Atomic Radius | 135.0 pm |
| Covalent Radius | 122.0 pm |
| Van der Waals Radius | 187.0 pm |
Discovery
| Discovered By | Lecoq de Boisbaudran |
| Discovery Year | 1875 |
| Location | Paris, France |
| Named After | Latin 'Gallia' meaning France; also a pun on 'gallus' (rooster, 'le coq') |
About Gallium
Gallium melts just above room temperature at 29.76 degrees C. It expands when it solidifies, like water. Gallium was predicted by Mendeleev as 'eka-aluminum' before its discovery and has one of the largest liquid ranges of any metal.
Uses & Applications
Semiconductor compounds (GaAs, GaN), LEDs, laser diodes, solar cells, and medical thermometers.
Fun Fact
Gallium melts at 29.76 degrees C, so it literally melts in your hand. There is a classic prank involving gallium spoons that dissolve in hot tea.
Isotopes
| Mass Number | Abundance | Half-Life | Stable |
| 69 | 0.60108% | - | Yes |
| 71 | 0.39892% | - | Yes |
Electron Configuration
[Ar] 3d10 4s2 4p1