Covalent bonding

• What do atoms form by sharing electrons?

  Covalent bonds
• Why do atoms transfer electrons in ionic bonds?

  To achieve a full outer shell
• What happens when two non-metal elements need extra electrons?

  They share electrons instead of transferring
• What is a dot and cross diagram used for?

  To represent shared electrons in covalent bonds
• How should you differentiate electrons in a dot and cross diagram?

  Use dots for one atom and crosses for another
• What is a displayed formula?

  A representation using chemical symbols and lines
• Why are displayed formulas advantageous for large molecules?

  They simplify drawing complex structures
• What is a limitation of displayed formulas?

  They do not show 3D molecular shapes
• What is the molecular formula for ammonia?

  NH₃
• How many hydrogen atoms are in ammonia?

  Three hydrogen atoms
• What do hydrogen atoms need to fill their outer shell?

  One extra electron
• How many electrons can nitrogen's second energy level hold?

  A maximum of eight electrons
• What is the result of hydrogen sharing electrons with nitrogen in ammonia?

  All atoms achieve full outer shells
• What does a 3D model represent in molecular structures?

  The actual arrangement of atoms in space
• What are simple molecular substances?

  Small molecules with strong covalent bonds
• What type of forces exist between individual molecules in simple molecular substances?

  Weak intermolecular forces
• What is the chemical formula for water?

  H₂O
• What is the chemical formula for methane?

  CH₄
• What are polymers made of?

  Repeating units called monomers
• What are giant covalent structures?

  Large structures with billions of atoms
• Why are giant covalent structures strong?

  All atoms are joined by covalent bonds
• How do covalent bonds differ in simple molecular substances and giant covalent structures?

  Simple substances have weak forces; giants have strong bonds
• What are the methods to represent covalent bonds?

  • Dot and cross diagrams
  • Displayed formulas
  • 3D models
• What are the characteristics of simple molecular substances?

  • Small molecules
  • Strong covalent bonds within molecules
  • Weak intermolecular forces between molecules
• What is the significance of sharing electrons in covalent bonding?

  • Achieves full outer shells for atoms
  • Stabilizes the molecule