Covalent bonds

• What is a covalent bond?

  An electrostatic attraction between shared electrons
• How can you identify a compound with covalent bonds?

  It contains only non-metal elements
• What occurs when atoms form covalent bonds?

  Atoms share a pair of electrons
• What is a dative covalent bond?

  A bond from one atom's electron pair
• How many unpaired electrons does nitrogen have in ammonia?

  Three unpaired electrons
• What is a lone pair in chemistry?

  Non-bonded electrons on an atom
• What do dots and crosses represent in dot and cross diagrams?

  Dots are one atom's electrons, crosses are another's
• How does the ammonium ion form?

  From ammonia and a hydrogen ion
• What type of bond forms between nitrogen and hydrogen in the ammonium ion?

  A dative covalent bond
• How many pairs of electrons do oxygen atoms share with carbon in carbon dioxide?

  Two pairs of electrons
• What is the relationship between bond length and bond strength in covalent bonds?

  Shorter bonds are stronger
• What is an example of a giant covalent structure?

  Diamond
• Why do giant covalent structures have high melting points?

  Many strong covalent bonds need breaking
• What shape does methane form due to electron pair repulsion?

  Tetrahedral shape
• What is the bond angle in methane?

  $109.5^\circ$