Question #9d69f

The idea here is that every covalent bond that #"X"# forms with another atom will require one or more valence electrons, depending on the type of bond it forms.

According to the octet rule, atoms are most stable when they have eight electrons in their outermost shell, which is called the valence shell.

With the exception of noble gases, which already have a complete octet, all the other atoms in the periodic table will have to form various bonds in other to obtain that stable octet configuration.

Nonmetals will form covalent bonds with each other. Covalent bonds are characterized by the fact that electrons are shared between the two atoms.

Now, a nonmetal atom can form

• a single bond, which consists of one sigma bond
• a double bond, which consists of one sigma and one pi bond
• a triple bond, which consists of one sigma and two pi bonds

When two atoms form a sigma or a pi bond, they're essentially sharing two valence electrons, one from each of the two atoms. This means that you will get

• #"2 bonding electrons " -># a single bond
• #"4 bonding electrons " -># a double bond
• #"6 bonding electrons "-># a triple bond

You know that your atom #"X"# has formed a double bond to another atom. This means that a total of four valence electrons are being shared by the two atoms.

This double bond will thus ensure that atom #"X"# gets four valence electrons. To reach the eight needed for a complete octet, it needs four more valence electrons.

To get four more valance electrons, it can do one of two things

• form one double bond to another atom
• form two single bonds to two other atoms

Since you're looking for the maximum number of atoms that can be bonded to #"X"#, you're going to have to go with the second scenario.

This of course implies that atom #"X"# has two electrons to share, one with each of the two atoms.

Since two electrons are being shared in a single bond, atom #"X"# will ensure that it gets a complete octet by forming single bonds to two other atoms.

Therefore, the maximum number of atoms that can bond to #"X"# and still conform to the octet rule will be equal to #2#.

This scenario corresponds to the double bond illustrated in the above image.