covalent bonding

• How do atoms form covalent bonds?

  By sharing electrons
• What happens when atoms transfer electrons?

  They form oppositely charged ions
• Why do atoms transfer electrons?

  To achieve a full outer shell
• What is the result of sodium and chlorine's electron transfer?

  Formation of oppositely charged ions
• What do two chlorine atoms need to achieve a full outer shell?

  They need to share electrons
• 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 downside of displayed formulas?

  They do not show 3D molecular shapes
• How many hydrogen atoms are in ammonia?

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

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

  A maximum of eight electrons
• What happens when each hydrogen shares one electron with nitrogen?

  All atoms achieve full outer shells
• What is the purpose of a 3D model in chemistry?

  To show the arrangement of atoms
• What are simple molecular substances?

  Small molecules with strong covalent bonds
• What are polymers made of?

  Repeating units called monomers
• What are giant covalent structures?

  Large structures with billions of atoms
• What is the arrangement of atoms in giant covalent structures?

  In a regular lattice
• Why are giant covalent structures strong?

  All atoms are joined by covalent bonds