Covalent Bonds and Covalent Bonding in Carbon Video Lecture - Class 10

covalent bonds in this video you are
going to learn about covalent bonds how
they are made and how they form if you
haven't seen it already first have a
look at our video structure and bonding
only the noble gases exist naturally as
single atoms all the other elements of
the periodic table have partially filled
valence shells or outer electron shells
atoms bond by swapping or sharing
electrons in their outer shells when
very different atoms react like metals
and nonmetals
they normally swap electrons this is
ionic bonding
but when similar atoms react like
nonmetals combining with other nonmetals
they share electrons this is covalent
bond II nonmetals are found on the right
hand side and upper part of the periodic
table some common nonmetals are carbon
nitrogen oxygen and the halides they
have shells of electrons that are
normally half or more than half full of
electrons since they have a strong
attraction for a few additional
electrons it is energetically
unfavorable for them to lose electrons
so they share electrons by overlapping
orbitals this makes a bonding orbital or
covalent bond that contains two
electrons
if there is space in the outer shell a
non metal atom can form double or triple
bonds like in oxygen or nitrogen in the
displayed formula of a compound we
represent a covalent bond with a
straight line like this we can also
represent a covalent bond as a dot and
cross diagram these diagrams show only
the valence electrons to learn more
about Dawson cross diagrams watch our
video on Dawson cross diagrams
covalent bonds are directional which
means they are in a fixed position like
holding hands this is different from my
on earth ones which are formed with an
electrostatic attraction between charged
ions the overlap between orbitals means
that the atoms in covalent bonds are
very close
these things make covalent bonds strong
there are two kinds of covalent
structure small molecules like water and
giant compounds like diamond because the
electrons in the bonds are evenly shared
bonds are not polarized there is little
attraction between molecules and forces
between molecules are weak compounds
made from small covalent molecules have
low melting and boiling points and a
volatile they also don't conduct
electricity carbon and silicon tend to
form giant covalent compounds these bond
in the same way but instead of forming
small molecules with one or two bonds
they form for making up huge lattices or
chains of many many linked up atoms the
basis of the organic chemistry of carbon
or the chemistry of rocks one common
example is diamond which is made of
carbon each carbon atom forms four
covalent bonds because it has four
electrons in its outer shell to share
and has space for four more if every
carbon atom forms four bonds with four
other carbon atoms and each of these
forms four bonds with four other carbon
atoms and each of these forms four bonds
we very quickly end up with a very large
structure these compounds have very high
melting and boiling points because you
have to break covalent bonds rather than
intermolecular forces to make them free
enough to act as liquids or gases the
covalent bonds hold them rigidly in
place in the giant lattice
allotropes of non-metals bond covalently
allotropes are different structures of
the same element you can learn more
about these in our video allotropes of
nonmetals so to finish here's a
challenge for you which of these
compounds are covalent pause the video
for a moment whilst you think
have you considered their physical
properties and where the elements come
from on the periodic table solved it ok
the answer is all of these compounds are
covalent carbon dioxide carbon monoxide
and methanol are all small molecules
organic molecules form covalent bonds
between hydrogen and carbon c70 is a
fullerene a carbon molecule shaped like
a rugby ball closely related to the
buckminsterfullerene silicon dioxide is
a giant covalent structure and just like
diamond but has oxygen atoms bridging
between four coordinates silicon atoms
hopefully you now feel confident
identifying covalent compounds and
recognizing their properties
you