3. Covalent Bonding
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What is the nature of a covalent bond?
It is a bond formed when atoms share (pairs or multiple pairs of) electrons.
How many electrons are shared in a single, double and triple covalent bond?
single - 2 double - 4 triple - 6
Why do atoms stay close together in a covalent bond?
Both positive nuclei (in the bond) are attracted to the negative electrons shared between then; due to electrostatic forces; therefore they indirectly are attracted to each other.
Oxygen forms a double covalent bond. How many electrons are shared in the covalent bond?
4
What is the name a of particle where two atoms are bonded covalently?
diatomic (molecule)
Order the strength of the covalent bond in hydrogen, oxygen and nitrogen. Why is it this order?
Nitrogen, oxygen, hydrogen. Nitrogen has a triple bond, oxygen double and hydrogen single
Atoms need to be the same element in a diatomic molecule. True or False?
False - atoms can be different as long as there are two of them.
How many covalent bonds will the following elements make: hydrogen, sulfur, bromine, nitrogen, carbon?
hydrogen - 1 sulfur - 2 bromine - 1 nitrogen - 3 carbon - 4
What are the thermal properties of simple molecular covalent substances?
Very low or low melting and boiling points
Why do simple molecular covalent substances have low melting and boiling points?
There are strong covalent bonds within the molecule; There are weak intermolecular forces between molecules; Little energy is required to break the intermolecular forces.
What increases the melting and boiling points of simple molecular substances
Increasing the relative molecular mass.
What are the thermal properties of giant covalent substances?
Very high melting and boiling points.
Why do giant covalent substances have high melting and boiling points?
There are strong covalent bonds between all of the atoms; requiring a lot of energy to break.
What are electrical conductivity properties of covalent substances?
Most do not conduct electricity (with the exception of graphite and graphene.)
What are the properties of diamond and why?
Hard, high melting point; There are strong covalent bonds between all of the atoms; requiring a lot of energy to break.
What are the properties of graphite and why?
soft, conducts electricity There are strong covalent bonds between the atoms in the layers of graphite; there are weak intermolecular forces between the layers; delocalised electrons are free move in the channels between the layers of graphite.
What are the properties of C60 fullerenes?
Hard, high melting point, used as lubricants; There are strong covalent bonds between all of the atoms; requiring a lot of energy to break; they are spheres.
What are the uses of fullerenes?
Electronics lubricants drug delivery catalysts