Video Transcript
The valence shell of oxygen is the
second electron shell and contains six electrons. How many covalent bonds can oxygen
form?
The valence shell is the outermost
electron shell. The electrons in the valence shell
are the electrons that are involved in the formation of bonds and ions. This is because atoms will
typically gain, lose, or share electrons and bonds so that they have a full outer
shell, which is typically eight valence electrons. The problem tells us that oxygen
has six valence electrons. But if the problem didn’t give us
this information, we would be able to determine the number of valence electrons
using the periodic table, since for main group elements, the number of valence
electrons is consistent down a group.
Either way, since oxygen has six
valence electrons, it will gain two electrons according to the octet rule so that it
can have a full valence shell. It can do this by either forming an
ion or by forming bonds. But this question specifically
asked us about how many bonds oxygen can form. When atoms bond covalently,
electrons are shared between atoms with each atom that’s participating in the bond,
giving one of its electrons to the bond. So each covalent bond that an atom
forms will effectively make it gain one electron. So oxygen can form two covalent
bonds, which is what we see in molecules that oxygen forms when it bonds covalently,
like H2O where oxygen is bonded to two hydrogens.
