Bonding Flashcards
When does pure covalent bonding occur?
In covalent bonds when both atoms have the same electronegativity so they have an equal ‘pull’ on the shared electron
When does polar covalent bonding occur? What is it?
In covalent bonds when the atoms have different electronegativity and the atom with the higher electronegativity attracts the electron more strongly resulting in a slightly negative and slightly positive sides of the atom.
A compound is ‘more ionic’ when there is…
The greatest difference in electronegativity
______ compounds will conduct electricity when _______ or dissolved in water. _______ compounds will not conduct
Ionic, molten, covalent
Ionic compounds have ___ melting points
High
Ionic compounds are usually soluble in….
Water
What are the 3 types of van der waals’ forces?
- London dispersion forces
- Permanent dipole - permanent dipole interactions
- Hydrogen bonding
What causes London dispersion forces?
The uneven distribution of moving electrons forming temporary dipoles causing one side of an atom to become slightly negative and slightly positive
What do permanent dipole- permanent dipole interactions need to occur?
Polar molecules
When does hydrogen bonding occur?
Where there is an atom of H joined to an atom of N, O or F
What’s the strongest van der waals’ force?
Hydrogen bonding
What’s the weakest van der waals’ force?
London dispersion forces
Why does octane (C8H18) higher boiling point than methane (C1H4)?
As octane is a larger molecule the London dispersion forces are strong and therefore need more energy to break
Polar and ionic substances will dissolve in …
Polar solvents
Non-polar substances will only dissolve in…
Non-polar solvents
Viscous liquids have ____ intermolecular forces
Strong
_______ the number of hydroxyl groups will increase the viscosity of a liquid
Increasing
Why can ice float on water?
When water molecules freeze the molecules align themselves into an open lattice structure so as to maximise the strength of the hydrogen bonding between them. This means there is more space between them is solid form than liquid form, therefore ice is less dense.
