Covalent bonding Flashcards
Are covalent bonds present in Metals or non- metals
Non metals
What is covalent bonding
A covalent bond is when electrons are shared between non- metal atoms.
The number of electrons shared depends on how many extra electrons an atom needs to make a full outer shell.
What are the three types of structures in the from of covalent bonds
Giant Covalent bonds
small molecules
Large molecules
Explain Giant Covalent Bonds
Giant Covalent bonds -many billions of atoms, each one with a strong covalent bond to a number of others.
One example would be diamond, which has 4 carbon bonds to one atom
Explain small molecules bonds
Each Molecule contains only a few atoms with strong covalent bonds between these atoms. Different molecules are held together by weak intermolecular forces
One example is water
Explain Large Molecules Bonds
Many repeating units join covalent bonds to form a chain.
separate chains are held together by intermolecular forces that are stronger than in small molecules
An example would be polymers
Properties of Covalent bonded atoms
High bp or mp because the strong covalent bonds must be broken, hence it requires a lot of energy , solid at room temp.
Also most covalent structures do not conduct electricity, as they do not have a delocalised electron or ion to carry charge.
Graphite properties
Structure- only carbon atoms with 3 others attached.
horizontal layers that stack on top of each
other with weak intermolecular forces
between the layers
Hardness- weak intermolecular forces mean the layers
can slide over each other which is why its
soft.
Conductivity- Delocalised electron free to move
through graphite, so it can carry charges
and allow current to flow
properties of simple molecules
-They have low mp and bp.
-Have no overall charge, so they cannot conduct
electricity
-Weak intermolecular forces between simple molecules are why they have low bp and mp
Graphene properties
Single layer of graphite, which has strong covalent bonds, with no layers which make it strong/hard
Can conduct electricity
Properties of Fullerenes
Hollow Balls of carbon which can have varying numbers of atoms.
Weak intermolecular forces in between layers
Can be used as lubricants and in drug delivery within the body
Properties of Nanotubes
The carbon atoms in Nanotubes are arranged in a cylindrical tubes
High tensile strength ( difficult to break when pulled) is useful in the world of electronics
What are Vander-walls forces
2 molecules, one with negative charges on the right, the other on the left. Since they are both the same charge the stronger negative charge repels the weaker one so, in this case the left hand side ones are pushed to the other side if the atom. Now both have negative charges on the left, with the second atom having positive charge on the right. the left negative and right positive attract, this is van der waals forces.
Van der Waals forces include attraction and repulsions between atoms, molecules, and surfaces, as well as other intermolecular forces. They differ from covalent and ionic bonding in that they are caused by correlations in the fluctuating polarizations of nearby particles
https://socratic.org/questions/why-do-van-der-waals-forces-hold-molecules-together
Important to note that van der waals forces are weaker than covalent bonds, as they are a type of intermolecular force
Hydrogen Bonds
Strong yet weaker than covalent bonds.
water is an example, as it has hydrogen in it.
Water should be a gas at room temp, however as it has hydrogen bonding, the water molecules attract other water molecules, hence remaining as a liquid.
as the hydrogen bonds are hard to break, water remains a liquid at room temp
How are polymers formed (addition)
The intermolecular forces break, leaving one force still connecting atoms. the one that broke off is used to attach another atoms
example
c=c c=c , c=c -c-c, -c-c-c-c .
creates chain
