🔹 Basic Information

• Element Name: Selenium
• Discovered By: Jöns Jacob Berzelius
• Year of Discovery: 1817
• Category: Nonmetal
• Group: 16 (Group VIA – Chalcogens)
• State at Room Temperature: Solid (gray, red, or black forms) ⚫🔴

Selenium is a nonmetal with properties similar to sulfur. It exists in different forms — including shiny gray crystals or red powder — and it plays a surprising role in electronics, health, and industry.

🔸 Chemical Properties

• Chemical Symbol: Se
• Atomic Number: 34
• Atomic Mass: ~78.96 u
• Valency: Usually 2, 4, or 6
• Electronic Configuration: [Ar] 3d¹⁰ 4s² 4p⁴

Selenium is moderately reactive and forms compounds like selenides and selenates. It behaves both like a nonmetal and a metalloid in some ways, especially in electrical conductivity.

📘 Basic Things to Know

Selenium was named after the Greek word “Selene,” meaning Moon, because it was discovered shortly after tellurium (named after Earth 🌍).

It’s found in metal ores and soil, and is essential in small amounts for humans and animals — but can be toxic in large doses.

🤔 Interesting Facts

• Selenium is a semiconductor, meaning it can conduct electricity under certain conditions — like light exposure. 💡⚡
• It’s used in solar panels and photocopiers.
• In tiny amounts, selenium is important for our health, supporting the immune system and thyroid. 🧠
• Some types of glass contain selenium to reduce glare and color. 🪟
• Plants absorb selenium from soil — so it’s in our food chain naturally. 🌾🥗

🔧 Common Uses

• Glass Manufacturing: Used to remove color and tint glass reddish for aesthetics. 🔴
• Electronics: Selenium is used in solar cells, light sensors, and rectifiers. ⚡🔋
• Health Supplements: Found in vitamins and mineral supplements in trace amounts. 💊
• Pigments: Used to color plastics, ceramics, and paints. 🎨
• Photography (historically): Was once used in photocopying and light meters. 📷

📚 Conclusion

Selenium is a versatile and essential nonmetal with surprising roles in technology, health, and industry. From solar panels to supplements, it’s a great example of how elements work behind the scenes to improve modern life. For students, selenium shows how tiny atoms can have powerful effects! 🌟🔬