Chemical Formulae of elements

• What do chemists use to represent elements and compounds?

  Symbols and formulae
• What do word equations and balanced chemical equations represent?

  The changes that happen in chemical reactions
• What is a chemical formula?

  • A combination of symbols
  • Indicates the chemical composition of a substance
• What is an element?

  A substance made of one type of atom only
• What is a compound?

  A substance formed by the chemical union of two or more elements
• What is the formula for most elements?

  Its chemical symbol
• What is a balanced chemical equation?

  A chemical equation where the number of units of each element is the same on both sides of the arrow
• What is the chemical symbol for helium?

  He
• What is the chemical symbol for lithium?

  Li
• What is the chemical symbol for beryllium?

  Be
• What is the chemical symbol for neon?

  Ne
• What is the chemical symbol for boron?

  B
• What is the chemical symbol for carbon?

  C
• What is the chemical symbol for sodium?

  Na
• What is the chemical symbol for magnesium?

  Mg
• Which elements exist as molecules made up of two atoms?

  • Iodine (I₂)
  • Bromine (Br₂)
  • Chlorine (Cl₂)
  • Fluorine (F₂)
  • Oxygen (O₂)
  • Nitrogen (N₂)
  • Hydrogen (H₂)
• What is a molecule?

  A collection of two or more atoms held together by chemical bonds
• What is the mnemonic to remember the elements that exist as molecules?

  I B ring C lay F or O ur N ew H ouse
• What is the subscript used for in chemical formulae of molecules?

  It indicates the number of atoms in the molecule
• Why is it important to remember which elements exist as molecules?

  To use the correct form in chemical equations involving these elements
• What are the chemical formulae of the elements neon, nitrogen, and sodium?

  Ne, N₂, Na
• What are the key facts about chemical formulae of elements?

  • Use symbols to represent elements
  • Important to know first 20 elements and groups 1 and 7
  • Some non-metal elements exist as molecules