The octet rule is a chemical principle that states that atoms tend to gain, lose, or share electrons in order to achieve a stable electron configuration with 8 valence electrons.
In NO2, nitrogen has 5 valence electrons and needs 3 more to achieve an octet. It can either gain one electron to form NO2- or share 2 electrons through a double bond to form NO2. In ClO-, chlorine has 7 valence electrons and needs one more to achieve an octet. It can gain an electron to form ClO- or share an electron through a single bond to form ClO.
The octet rule is a general guideline and not a strict rule. Some molecules, such as those with an odd number of valence electrons or those with expanded valence shells, do not follow the octet rule.
Atoms in period 3 or higher on the periodic table can have expanded valence shells, meaning they can have more than 8 valence electrons. This is because these atoms have access to d orbitals, which can accommodate additional electrons.
Yes, some molecules can have less than 8 valence electrons and still be stable. Examples include beryllium and boron compounds, which can have 4 and 6 valence electrons, respectively.