Definition & Classification

Pure Elements are substances composed of only one type of atom, existing in:

• Free (Native) State: Naturally uncombined (e.g., gold nuggets, diamond)
• Allotropes: Different structural forms (e.g., graphite vs. diamond for carbon)

Key Feature:

• Defined by atomic number (proton count) on the periodic table.

---

Forms of Pure Elements

Category	Description	Examples
Metals	Conductive, malleable	Gold (Au), Iron (Fe), Aluminum (Al)
Nonmetals	Brittle, insulators	Sulfur (S), Oxygen (O₂), Iodine (I₂)
Metalloids	Semi-conductive	Silicon (Si), Boron (B)

Allotrope Examples:

• Carbon: Graphite (conductive), Diamond (hardest natural material)
• Phosphorus: White (toxic), Red (stable), Black (semiconductor)

---

Key Properties

Property	Metals	Nonmetals
State at RT	Mostly solid (except Hg)	Gas (O₂), Solid (S), Liquid (Br₂)
Conductivity	High (heat/electricity)	Low (except graphite)
Reactivity	Varies (Na reactive, Au inert)	High (Cl₂), Low (N₂)

---

Industrial Applications

Element	Use Case	Industry
Silicon	Semiconductor chips	Electronics
Gold	PCB coatings, jewelry	Electronics/Luxury
Sulfur	Vulcanizing rubber	Automotive
Oxygen	Medical gas, steelmaking	Healthcare/Metallurgy

---

Extraction & Purification

Method	Target Elements	Process Example
Electrolysis	Aluminum (Al), Chlorine (Cl₂)	Hall-Héroult process (Al₂O₃ → Al)
Smelting	Iron (Fe), Copper (Cu)	Blast furnace (Fe₂O₃ → Fe)
Distillation	Zinc (Zn), Mercury (Hg)	Retort processing (ZnO → Zn)

---

Safety & Storage

• Metals:
  • Store in dry conditions (prevent oxidation, e.g., Na in oil)
• Nonmetals:
  • Gas cylinders (O₂, N₂) with pressure regulators
  • Toxic solids (e.g., white P) under water/inert gas