Chemical Bonding Flashcards
Define an Intramolecular bond.
An intramolecular bond is defined as a bond occurring between atoms within molecules.
Define electronegativity.
Electronegativity is defined as the measure of the tendency of an atom to attract a bonding pair of electrons.
Define the term ‘covalent bond’
A covalent bond is defined as the sharing of at least one pair of electrons by two atoms.
Define the term ‘non polar covalent (or pure covalent) bond’
A pure covalent (non polar covalent) bond is an equal sharing of electrons by two atoms.
Define the term ‘polar covalent bond’
Polar covalent bond is defined as the unequal sharing of electrons leading to a dipole forming (as a result of the electronegativity difference).
A zero difference in electronegativity indicates a ______________ covalent bond between atoms.
Non-polar (pure)
A non-zero difference in electronegativity indicates a __________ covalent bond between atoms.
Polar
Define the term ‘ionic bond’
An Ionic bond is defined as a transfer of electrons and subsequent electrostatic attraction. (Generally between metals and non-metals/polyatomic ions)
Define metallic bonding.
Metallic bonding is the bond that exists between a positive kernel and a sea of delocalized electrons.
Define intermolecular force.
Intermolecular force is defined as a weak force of attraction between molecules or between atoms of noble gases.
Name the two types of Van Der Waals forces.
Dipole - dipole forces
London forces
Name the two types of intermolecular forces.
Van der Waals forces and Hydrogen bonding.
How is melting point affected by various intermolecular forces?
Melting point – the greater the intermolecular forces, the higher the melting point. As intermolecular forces increase, more energy is required to release the molecules from these forces.
How would viscosity be impacted by the various intermolecular forces?
Viscosity – the greater intermolecular force, the greater the viscosity. This is because the stronger the molecules are held together, the more “syrupy” the structure becomes.
How would vapor pressure be impacted by the various intermolecular forces?
Vapour pressure - the greater intermolecular forces between molecules, the lower the vapour pressure. The higher the intermolecular forces, the harder it is for the molecule to change phases and so there would be less vapour and thus decreased vapour pressure.
List a type of covalent structure and it’s properties. (D)
Covalent network crystal. (In the case of diamond) , has an extremely high boiling point (4000°)
Very strong carbon-carbon covalent bonds have to be broken throughout the structure before melting occurs.
Is extremely hard (again due to strong carbon-carbon bonds acting in three dimensions).
Doesn’t conduct electricity (all the electrons are held tightly between atoms, aren’t free to move).
List a type of covalent structure and it’s properties. (G)
Layer structure (graphite). Is softDelocalized electrons that can move freely throughout the layer (no inter layer connection between electrons). Atoms within sheets are held together by strong covalent bonds (stronger than diamond because diamonds do not have the additional London forces created by the delocalized electrons.)
Give properties of ionic structures.
Strong electrostatic attractions between cation and anion, requiring lots of heat energy to overcome. High melting and boiling points. Brittle, if an ion layer gets shifted then ions of the same charge would be side by side and the crystal repels itself to pieces.
What structure is a metallic lattice
Metallic lattice consists of metal cations surrounded by a sea of delocalized electrons. Good conductors. Generally high BP due to the attraction between the electrons and the cation (positive kernels).
State the rule of solubility.
In general polar substances easily dissolve in polar solvents, and non polar substances dissolve in non polar solvents. Many ionic compounds are also soluble in polar solvents. It is often stated that like dissolves like.
