Chemical Changes and Structure - Bonding Flashcards
What is a non-polar covalent bond?
Where both atoms have an equal “pull” on the shared electrons (they have the same electronegativity).
What is a polar covalent bond?
A bond formed when a shared pair of electrons are not shared equally. This is due to one of the elements having a higher electronegativity than the other. The atom with the higher electronegativity attracts electrons more strongly than the other atom. This results in the atom with the higher electronegativity having a slight negative charge (δ-) and the other has a slight positive (δ+) charge.
Explain ionic bonding.
Atoms with a large difference in electronegativity may form ionic bonds. This does not involve sharing electrons but electrons being transferred from one atom to another, causing one to be negatively charged and the other positively charged.
How do you predict the number of ions in a lattice?
Mg ²⁺ (Cl-)₂ tells us there are two Chloride ions for every Magnesium ion. Therefore, if you know there were two million Magnesium ions in a lattice, you should be able to predict the four million Chloride ions.
Describe the bonding continuum.
A difference of 0.0 to 0.5 electronegativity means it’s a non-polar covalent bond, and a London Dispersion Force. Between 0.5 and 2.0 means it’s a polar covalent bond and a Permanent dipole - Permanent dipole interaction. Anything above 2.0 is an ionic bond.
Describe London Dispersion Forces (two points, one example).
- Temporary.
- Induced dipole.
- E.g. between halogens and noble gases.
Describe Permanent dipole - Permanent dipole interactions (two points).
- Permanent dipole.
- Between polar molecules.
Describe Hydrogen bonding (two points, one example).
- Strongest Van der Waals force.
- Between polar molecules where H is directly bonded to N, O or F.
- E.g. water molecules.
What causes polarity to cancel?
A symmetrical arrangement of polar bonds (e.g. CCl₄)
What can polar solvents dissolve in?
Polar and ionic substances.
What is the rule of solubility?
Like dissolves like.
What is the definition of viscosity?
The ‘thickness’ of a substance.
