C2

• What are ions in chemistry?

  Charged particles, single or groups of atoms
• How do ions form?

  By transferring electrons between atoms
• What is a stable electronic structure?

  Full outer shell like a noble gas
• What happens when metals form ions?

  They lose electrons to form positive ions
• What happens when non-metals form ions?

  They gain electrons to form negative ions
• How is the charge of an ion determined?

  By the number of electrons lost or gained
• Which groups of elements are most likely to form ions?

  Groups 1, 2, 6, and 7
• What do Group 1 and 2 elements form?

  Positive ions (cations)
• What do Group 6 and 7 elements form?

  Negative ions (anions)
• What charge do Group 1 elements form?

  1+ ions
• What charge do Group 2 elements form?

  2+ ions
• What charge do Group 6 elements form?

  2- ions
• What charge do Group 7 elements form?

  1- ions
• How does a sodium atom form a sodium ion?

  By losing 1 electron
• How does a magnesium atom form a magnesium ion?

  By losing 2 electrons
• How does a chlorine atom form a chloride ion?

  By gaining 1 electron
• How does an oxygen atom form an oxide ion?

  By gaining 2 electrons
• What is ionic bonding?

  • Transfer of electrons between metal and non-metal
  • Metal loses electrons, forming positive ions
  • Non-metal gains electrons, forming negative ions
  • Oppositely charged ions attract each other
• What do dot and cross diagrams represent?

  Arrangement of electrons in atoms or ions
• What does a sodium chloride (NaCl) dot and cross diagram show?

  Sodium gives up an electron to chlorine
• What is the structure of ionic compounds?

  Giant ionic lattice structure
• What holds the ions in an ionic lattice together?

  Strong electrostatic forces of attraction
• What are the properties of ionic compounds?

  High melting and boiling points
• Why can't solid ionic compounds conduct electricity?

  Because ions are held in place
• Why can molten ionic compounds conduct electricity?

  Because ions are free to move
• What happens when ionic compounds dissolve in water?

  They separate into free-moving ions
• How do you find the empirical formula of an ionic compound?

  Balance the charges of the ions
• What is the empirical formula of potassium oxide?

  K₂O
• What is covalent bonding?

  • Atoms share pairs of electrons
  • Occurs between non-metal atoms
  • Creates strong covalent bonds
  • Achieves full outer shells for stability
• What do covalent bonds involve?

  Sharing of electrons between atoms
• What is the role of electrostatic forces in covalent bonds?

  Attract positively charged nuclei to shared electrons
• What is a displayed formula?

  Shows covalent bonds as lines between atoms
• What is the molecular formula of ethane?

  C₂H₆
• What are the properties of simple molecular substances?

  • Weak intermolecular forces
  • Low melting and boiling points
  • Usually gases or liquids at room temperature
  • Do not conduct electricity
• What is a polymer?

  Long chains of repeating units
• How do you find the molecular formula of a polymer?

  Write the formula of the repeating unit with 'n'
• What are giant covalent structures?

  Macromolecules with strong covalent bonds
• What are the melting and boiling points of giant covalent structures?

  Very high due to strong bonds
• What are covalent bonds?

  Strong bonds formed by shared electrons
• What is a repeating unit in a polymer?

  The shortest repeating section of a polymer