Table of Contents
Introduction of Octet Rule
The octet rule is a guideline that states that atoms in a molecule strive to have eight electrons in their outermost shell. This rule helps to explain why atoms of different elements form different types of molecules. For example, the element helium has two electrons in its outermost shell and can therefore form only very simple molecules. The element oxygen has six electrons in its outermost shell and can form much more complex molecules.
What is the Octet Rule?
The octet rule is a chemical rule of thumb that states that atoms of main-group elements tend to form molecules in which each atom has eight electrons in its outermost shell. This rule is a consequence of the electron configuration of atoms, in which the outermost electron shell is full when it contains eight electrons.
Octet Rule in Chemistry
The octet rule states that atoms in a molecule strive to have eight electrons in their valence shell. This rule is especially important in the chemistry of the elements in the second row of the periodic table, because these elements have a valence of two.
Octet Rule Examples
- The octet rule is a simple idea in chemistry that states that atoms of elements tend to form molecules in which they have eight electrons in their outermost energy level. This rule is often called the “rule of eight” or the “octet rule.”
- There are a number of examples of the octet rule in action. One of the most common is hydrogen gas, which consists of molecules made up of two hydrogen atoms. Each hydrogen atom has one electron in its outermost energy level, and when the atoms come together to form a molecule, they share those electrons so that each atom has two electrons in its outermost energy level. This makes the molecule stable and happy.
- Another common example is oxygen gas. Oxygen gas molecules consist of two oxygen atoms. Each oxygen atom has six electrons in its outermost energy level, and when the atoms come together to form a molecule, they share those electrons so that each atom has eight electrons in its outermost energy level. This makes the molecule stable and happy.
- There are countless other examples of the octet rule in action, in everything from simple molecules like water and methane to more complex molecules like DNA and proteins. In general, atoms tend to form molecules in which they have eight electrons in their outermost energy level, and this rule is one of the basic principles that governs the formation of molecules in chemistry.
Exceptions to the Octet Rule
The octet rule is not always followed. Some elements do not have eight electrons in their outer shell and therefore cannot follow the octet rule.
Some elements that do not have eight electrons in their outer shells are:
- Halogens (F, Cl, Br, I)
- Noble gases (He, Ne, Ar, Kr, Xe)
- Sulfur
- Carbon
- Nitrogen
- Oxygen
Stability of an Atom
The stability of an atom is determined by the number of protons and neutrons in the nucleus. The more protons and neutrons in the nucleus, the more stable the atom is.
Octet Rule and Valence Electron
- The octet rule is a rule in chemistry that states that atoms of a particular element tend to form molecules in which each atom has eight electrons in its outermost shell. The octet rule is also referred to as the “duet rule” because atoms of the first row of the periodic table of elements (He, Ne, Ar, Kr, Xe) usually have two electrons in their outermost shell.
- Valence electrons are the electrons in the outermost shell of an atom. The octet rule is most often applied to atoms in their ground state, meaning the atoms have the lowest possible energy.
Hypervalent Iodine
Polyatomic Iodine
- Iodine is a polyatomic ion with the formula I-. It is the simplest of the polyatomic halogens, consisting of a single atom. The oxidation state of iodine is -1.
- Iodine is a bluish-black solid that is soluble in water and slightly soluble in ethanol. It is highly reactive and toxic. Iodine used in the manufacture of pharmaceuticals and in the production of dyes.
- The most common valence of iodine is -1. However, iodine can also have a valence of +1, as in the I- ion. In this ion, the iodine atom has a positive charge and the electrons in the outermost shell are in the s orbital.
