Covalent Bonding and Simple Molecules

• What is a covalent bond?

  A shared pair of electrons between two non-metals
• In which types of substances does covalent bonding occur?

  In non-metal compounds and non-metal elements
• What do molecular formulas indicate?

  How many atoms of each element are in a compound
• What does a displayed formula show?

  It shows the arrangement of atoms but not 3D structure
• What is a limitation of ball and stick diagrams?

  They don't show which atoms the electrons come from
• What is a limitation of dot and cross diagrams?

  They don't show relative sizes of atoms
• How strong are covalent bonds compared to forces between molecules?

  Covalent bonds are strong; intermolecular forces are weak
• What are some examples of simple molecular substances?

  Hydrogen, oxygen, nitrogen, chlorine
• What is the molecular formula for water?

  H₂O
• What is the molecular formula for ammonia?

  NH₃
• What is the molecular formula for methane?

  CH₄
• What are the two properties of simple molecular substances?

  • Low melting and boiling points
  • Don't conduct electricity
• Why do simple molecular substances have low melting and boiling points?

  Less energy is needed to break weak forces
• What state are most simple molecular substances at room temperature?

  Mostly gases or liquids
• Why don't simple molecular substances conduct electricity?

  There are no charged particles to carry charge