2.2.2 Bonding and structure Flashcards
Define ionic bonding.
Electrostatic attraction between oppositely charged ions.
Why do ionic compounds form giant ionic lattices?
Because oppositely charged ions are strongly attracted in all directions.
Explain why NaCl forms a giant ionic lattice.
Na+ and Cl- ions attract each other strongly in all directions
Explain the high melting point of ionic compounds.
Strong electrostatic forces between ions require large amounts of energy to break.
Explain the solubility of ionic compounds in water.
Ionic compounds are soluble as polar water molecules attract and surround ions.
Explain why ionic compounds conduct electricity when molten or aqueous.
Ions are free to move and carry charge.
Define covalent bonding.
Strong electrostatic attraction between a shared pair of electrons and the nuclei of bonded atoms.
What is a single covalent bond?
A shared pair of electrons between two atoms.
What is a multiple covalent bond?
Two or more shared pairs of electrons between atoms (e.g.
What is a dative covalent (coordinate) bond?
A shared pair of electrons donated by one atom.
What does average bond enthalpy measure?
Strength of a covalent bond.
State the relationship between bond enthalpy and bond strength.
Larger average bond enthalpy = stronger covalent bond.
What is electron pair repulsion theory?
Electron pairs around a central atom repel to positions of minimum repulsion.
Explain why lone pairs repel more than bonded pairs.
Lone pairs are closer to the nucleus and occupy more space.
State the bond angle in CH4.
109.5° (tetrahedral).
State the bond angle in NH3.
107° (pyramidal).
State the bond angle in H2O.
104.5° (non-linear).
State the shape and bond angle of a molecule with 2 bonding pairs.
Linear
State the shape and bond angle of a molecule with 3 bonding pairs.
Trigonal planar
State the shape and bond angle of a molecule with 4 bonding pairs.
Tetrahedral
State the shape and bond angle of a molecule with 3 bonding pairs and 1 lone pair.
Pyramidal
State the shape and bond angle of a molecule with 2 bonding pairs and 2 lone pairs.
Non-linear
State the shape and bond angle of a molecule with 6 bonding pairs.
Octahedral
Define electronegativity.
The ability of an atom to attract the bonding electrons in a covalent bond.