Cr - Chromium

Chromium (Cr) is a lustrous, hard, and brittle metal known for its high melting point, corrosion resistance, and shiny finish when polished. It is the first element in Group 6 of the periodic table, with an atomic number of 24.

Physical Characteristics:

• Atomic Number: 24
• Atomic Weight: 51.9961 u
• Density: 7.19 g/cm³ at 20°C
• Melting Point: 1907°C (3465°F)
• Boiling Point: 2671°C (4840°F)
• State at Room Temperature: Solid
• Appearance: Silvery, lustrous, and hard

Applications:

1. Stainless Steel Production: Chromium is a crucial component in stainless steel, contributing to its corrosion resistance, durability, and shiny appearance. Approximately 85% of the chromium consumed is used in the production of stainless steel.
2. Metal Plating: Chromium plating, also known as chrome plating, is applied to metal objects to provide a decorative finish, corrosion resistance, and increased surface hardness. This is common in automotive parts, tools, and kitchen appliances.
3. Dyes and Pigments: Chromium compounds are used to produce green, yellow, red, and orange pigments for paints, inks, and plastics due to their vibrant colors and stability.

Significant Compounds:

1. Chromium(III) Oxide (Cr2O3): Used as a pigment (chrome green) and in the abrasive industry for polishing and grinding.
2. Chromium(VI) Oxide (CrO3): Employed in chrome plating and as an oxidizing agent in organic synthesis, though its use is regulated due to toxicity concerns.
3. Potassium Dichromate (K2Cr2O7) and Sodium Dichromate (Na2Cr2O7): Used as oxidizing agents in various chemical reactions, in the manufacturing of pigments, and for wood preservation. Their use is also controlled due to environmental and health risks.

Basics on Chromium-Wikipedia