Bonding

• What is the key definition of metallic bonding?

  Attraction between delocalised electrons and positive ions
• In metals, positive metal ions are arranged in a giant metallic lattice.
• The mobile electrons in a metallic structure are called delocalised electrons.
• What determines the number of delocalised electrons in a metal?

  Electrons lost from each atom
• What is the key definition of ionic bonding?

  Electrostatic attraction between oppositely charged ions
• In ionic bonding, positive and negative ions are formed.
• What happens to metal atoms in ionic bonding?

  They lose electrons
• Match each ion with its electronic configuration:

  Sodium ion ↔️ 1s² 2s² 2p⁶

  Chloride ion ↔️ 1s² 2s² 2p⁶ 3s² 3p⁶
• How many electrons does an element in Group 6 gain to form an ion?

  2
• Boron in Group 3 forms ions.

  False
• Transition elements can form more than one stable type of ion.
• What is the formula for magnesium fluoride?

  MgF₂
• Match each compound ion with its formula:

  Ammonium ↔️ NH₄⁺

  Hydroxide ↔️ OH⁻

  Carbonate ↔️ CO₃²⁻

  Sulfate(VI) ↔️ SO₄²⁻
• A covalent bond is defined as a shared pair of electrons.
• Covalent bonding occurs between non-metal atoms.
• How are covalent bonds formed?

  Sharing of unpaired electrons
• A pair of electrons which is not bonded is called a lone pair.
• How many electron pairs are shared in a double bond?

  2
• A co-ordinate bond is a covalent bond in which both electrons of the shared pair come from the same atom.
• The atom donating the electrons in a co-ordinate bond has a lone pair.
• How is a co-ordinate bond represented in diagrams?

  An arrow
• The shape of molecules can be predicted using the Electron Pair Repulsion Theory.
• Lone pairs repel more strongly than bonding pairs.
• What is the correct order of repulsion strength between electron pairs?

  lone pair-lone pair > lone pair-bond pair > bond pair-bond pair
• Each lone pair reduces the bond angle by 2.5 degrees.
• Match each molecule with its shape and bond angle:

  BeCl₂ ↔️ Linear, 180°

  BF₃ ↔️ Trigonal planar, 120°

  CH₄ ↔️ Tetrahedral, 109.5°

  SF₆ ↔️ Octahedral, 90°
• A molecule with 2 bond pairs and 1 lone pair has a V-shaped or bent shape.
• What is the bond angle in ammonia (NH₃)?

  107°
• Compound ions can have specific shapes determined by electron pair repulsion.
• What is the shape of the AlCl₄⁻ ion?

  Tetrahedral
• What is electronegativity defined as?

  Atom's ability to attract electrons
• Electronegativity increases across a period because the nuclear charge increases
• Electronegativity decreases down a group because the atomic radius increases.
• Which atom is the most electronegative?

  Fluorine
• Noble gases have electronegativity values because they readily form covalent bonds.

  False
• What makes a bond polar?

  Uneven distribution of electrons
• A non-polar covalent bond occurs when there is no or a very small difference in electronegativity
• An ionic bond occurs when there is a large difference in electronegativity.
• Why are hydrocarbons non-polar?

  Similar electronegativity of C and H
• In a polar molecule like HCl, the polar bond creates a permanent dipole