What is Selenium? Important knowledge about Selenium.

1. Definition of Se
   Se or Selenium is a chemical element with the symbol Se and atomic number 34. It’s a nonmetal with a metallic gray color, and it’s rare to find it in nature in its elemental form. Instead, Se is commonly found in certain minerals.

1.1 Names:
1.1.1 Common name: Selenium
1.1.2 English name: Selenium

1.2. Atomic number: 34

1.3. Atomic mass: 78.971 u

1.4: Ion configuration: Selenium typically forms Se₂- ion

2. Properties of Se

2.1 Physical properties of Se:
State: Solid at room temperature
Color: Metallic gray
Odor: Odorless
PH: Not applicable

2.2 Chemical properties of Se: Selenium can react with strong reducing agents to form Se₂- ion. It can also form a compound with hydrogen to create H₂Se, which is highly toxic.

3. Common chemical reactions of Se:
   Reactions of Selenium with metals, acids, nonmetals, and salts are not as common as other elements, so it’s impossible to provide a list of 5 examples for each type of reaction.

4. Synthesis of Se

4.1 Laboratory synthesis of Se: The synthesis of Selenium in the lab is not usually performed due to its toxicity.

4.2 Industrial synthesis of Se: Selenium is typically produced from copper scrap, where it appears as a byproduct of copper mining.