Indium (In)
| Atomic Number | 49 |
|---|---|
| Atomic Mass | 114.8181 u |
| Category | Post-transition metal |
| Electron Config | [Kr] 4d¹⁰ 5s² 5p¹ |
| Appearance | silvery lustrous gray |
| Density (STP) | 7310 g/L |
| Melting Point | 429.7485 K |
| Boiling Point | 2345 K |
| Electronegativity | 1.78 (Pauling) |
| Ionization Energy | 558.3 kJ/mol |
| Atomic Radius | 155 pm |
| Crystal Structure | Centered Tetragonal |
| Discovered By | Ferdinand Reich (1863) |
Brief Introduction
Indium (In) is a soft, malleable, silvery-white post-transition metal that is extremely rare. It remains soft and ductile at very low temperatures and is used primarily in electronic displays. Key details about Indium (In) are as follows:
Uses: Primarily used in indium tin oxide (ITO) for transparent conductive coatings in touchscreens, LCD displays, and solar cells. Also used in solders and alloys (low-melting alloys), semiconductors (indium phosphide, indium arsenide), and in research (cryogenics, nuclear applications).
Production/Extraction: Produced as a byproduct of zinc, tin, copper, and lead ore processing (indium never occurs in significant quantities independently). China, South Korea, and Japan are major producers/refiners. Extremely rare element.
History: Discovered by Ferdinand Reich and Hieronymous Theodor Richter in 1863 through spectroscopic analysis of zinc ores. Named from the indigo blue line in its emission spectrum (Latin "indicum," indigo).
Health Effects & Safety: Considered relatively non-toxic in metallic form, though safety data is limited. Indium compounds can be toxic with occupational exposure. Some studies suggest potential lung toxicity from indium compounds. No known biological role.
Price/Market: Expensive and subject to supply volatility. Increasing demand from touchscreens and displays has driven prices. Supply chain concentration in China creates concerns. Recycling from electronic waste becoming economically important.
Properties: Extremely soft and malleable (can be scratched with fingernail), remains ductile at very low temperatures, wets glass (sticks to glass), low melting point (157°C), emits high-pitched "tin cry" when bent, exhibits primarily +3 oxidation state, and forms transparent conductive oxides.
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