count the number of electrons with centra atom.1)if number of electron less then 8 ,it is a deficient compound(BH3 has 6 electrons with B therefore electron deficient)2)if number of electron around central atom more then 8 ,it is electron rich compound(SF6 has 12 electrons with S therefore electron rich)

Identifying Electron Deficient and Electron Rich Compounds

Introduction
Electron-deficient and electron-rich compounds are terms used to describe the electron distribution in molecules or ions. Understanding the electron density of a compound is crucial in predicting its reactivity and chemical behavior. Here, we will discuss how to easily identify electron-deficient and electron-rich compounds.

Electron-Deficient Compounds
Electron-deficient compounds are those that have fewer electrons than required to satisfy the octet rule. These compounds often contain elements from groups 13 to 17 of the periodic table, such as boron (B), aluminum (Al), and phosphorus (P). Here are some characteristics and indicators of electron-deficient compounds:

1. Incomplete Octet: Electron-deficient compounds typically have an incomplete octet of electrons in their valence shell. For example, boron trifluoride (BF3) has only six valence electrons.

2. Positive Formal Charges: Electron-deficient compounds often have positive formal charges on certain atoms. For instance, the boron atom in BF3 carries a formal charge of +1.

3. High Electronegativity Difference: Electron-deficient compounds often involve atoms with significantly higher electronegativity compared to the surrounding atoms. This creates a polar bond, such as in BF3.

4. Rigid and Planar Structures: Electron-deficient compounds tend to have planar or linear structures due to the lack of lone pairs and the repulsion between bonding pairs of electrons.

Electron-Rich Compounds
Electron-rich compounds, also known as electron-donating compounds, have an excess of electrons compared to the octet rule. These compounds usually contain elements such as nitrogen (N), oxygen (O), and sulfur (S). Here are some characteristics and indicators of electron-rich compounds:

1. Excess Lone Pairs: Electron-rich compounds often have one or more lone pairs of electrons on the central atom. For example, ammonia (NH3) has one lone pair on the nitrogen atom.

2. Negative Formal Charges: Electron-rich compounds can carry negative formal charges on certain atoms. In NH3, the nitrogen atom carries a formal charge of -1.

3. Low Electronegativity Difference: Electron-rich compounds involve atoms with similar or lower electronegativity, resulting in more evenly shared electron pairs.

4. Bent or Pyramidal Structures: Electron-rich compounds tend to have bent or pyramidal structures due to the presence of lone pairs that repel bonding pairs and distort the molecular geometry.

Conclusion
Identifying electron-deficient and electron-rich compounds can be done by considering factors such as the number of valence electrons, formal charges, electronegativity differences, and molecular structures. Electron-deficient compounds have an incomplete octet and positive formal charges, while electron-rich compounds possess excess electrons, lone pairs, and negative formal charges. Understanding the electron density in compounds is essential in predicting their behavior and reactivity in various chemical reactions.