Chemical Changes and Structure: Bonding Flashcards
When are ionic compounds formed?
When two atoms bond where there is a large difference in electronegativity.
How can ionic compounds be identified?
By their properties which include high melting points, conductors of electricity when molten and soluble in polar solvents
Covalent compounds are classed as what?
Polar or non-polar
Polar covalent bonds are formed when?
Two atoms with different electronegativity values form a covalent bond. The atom with the higher electronegativity value is assigned the symbol δ- and the atom with the lower value is assigned the symbol δ+
The bonding continuum is used to describe what?
The variation in bonding from ionic at one end to covalent at the other end. Polar covalent is in the middle of the continuum.
The attraction between covalent molecules are known as what?
Van der Waals’ forces
What are the three types of van der Waals’ forces, name them in order from weakest to strongest?
London dispersion forces (LDF), permanent dipole-permanent dipole interactions (pdp-pdp) and hydrogen bonds
Non-polar covalent bonds are formed between what?
Two atoms with the same electronegativity value. The atoms have an equal attraction for electrons in the covalent bond.
Compounds with polar bonds will form what?
Polar molecules provided the molecule is not symmetrical
Compounds with non-polar bonds will form what?
Non-polar molecules
Symmetrical compounds with polar bonds (such as CO2) will form what?
Non-polar molecules
Non-polar molecules are attracted to what?
Other non-polar molecules by LDF
Polar molecules are attracted to what?
Other polar molecules by pdp-pdp interactions or hydrogen bonding
Permanent dipole-permanent dipole interactions occur between what?
Molecules where the molecule has a permanent dipole, for example, between ICl molecules
Hydrogen bonding occurs where?
Between molecules that contain an atom of H bonded to an atom of N, O or F, for example, between alcohol molecules
