Intermolecular Bonding Flashcards
Polar bonds
When atoms attract bonding electrons unequally, one gets a slight negative charge and the other becomes slightly positively charged
δ-
slightly negative charge
δ+
slightly positive charge
Are polar substances soluble
yes
Are non polar substances soluble
no
What causes molecules to become attracted to one another
intermolecular bonds
what gives a good indication of strength of bonds between molecules
boiling point
What do the low boiling points of noble gases show
the bonds between atoms are very weak
What does the boiling point trend of alkanes show
longer molecules have stronger bonds between them
what has a higher boiling point - straight chain alkanes or their branched isomers
Straight chain alkanes as more contact points
what is a dipole
a molecule with a positive end and a negative end because of its polar bonds
What is a permanent dipole
When to atoms in a bond have substantially different electronegativities
How are instantaneous induced dipoles formed
Formed between covalent molecules due to oscillating electrons producing very small dipoles δδ-/δδ+
Induced dipoles
occurs if an unpolarised molecule is next to a dipole - the dipole attracts or repels electrons in the unpolarised molecule, inducing a dipole in it
ion dipole bond
between ions and a polar solvent when an ionic salt dissolves
Explain why sodium chloride has a high melting point
The strong force of attraction between ions (1)
A lot of energy is needed to break the ionic bonds (1)
Name two types of bonding that occur in graphite and state where they occur
The bonds are covalent between carbon atoms in planes (1)
There are Van der Waals forces/ induced dipole forces between planes of carbon atoms (1)
Name the type of bonding that exists in solid diamond
Covalent (1)
Explain the difference in density between graphite and diamond
The distance between layers in graphite is greater than the length of the covalent bond in diamond (1)
The atoms in diamond are more closely packed (1)
