writing formula

• H2, N2, O2, F2, Cl2, Br2, I2?

  diatomic elements
• Mon(o)?


  one
• Di?


  two
• Tri?


  3
• Tetra?


  4
• Penta?


  5
• Hexa?


  6
• H2O?


  water
• NH3?


  ammonia
• CH4?


  methane
• Valency of 2?


  zinc
• valency of 1?


  silver
• NH4?


  ammonium
• OH?


  hydroxide
• NO3?


  nitrate
• CO3?


  carbonate
• SO4?


  sulfate