Atoms follow the duplet rule by achieving a stable configuration with two electrons in their outermost shell.
Understanding the Duplet Rule
The duplet rule is a simplified version of the octet rule, which primarily applies to hydrogen (H) and helium (He). These elements have only one electron shell (the first shell), which can hold a maximum of two electrons. Therefore, they strive to achieve a filled first shell, making them stable.
Why Two Electrons?
- Electronic Configuration: Hydrogen (atomic number 1) has one electron and needs one more to complete its shell. Helium (atomic number 2) already has a filled shell with two electrons.
- Stability: A filled electron shell represents a stable, low-energy state.
How Atoms Achieve the Duplet Configuration
Hydrogen atoms can achieve a duplet configuration through:
- Covalent Bonding: By sharing an electron with another atom, like another hydrogen atom (forming H2) or a chlorine atom (forming HCl). In H2, each hydrogen atom effectively has two electrons in its vicinity due to the shared electrons.
- Ionic Bonding: By either losing its electron (forming H+, although rare) or gaining an electron (forming H-, hydride ion), though the former usually doesn't result in following the duplet rule.
Helium, having already a complete outer shell, is inert and does not readily form bonds.
Examples
- Hydrogen Molecule (H2): Each hydrogen atom shares its single electron with the other, creating a covalent bond. This sharing gives each hydrogen atom a duplet configuration.
Summary
In essence, atoms like hydrogen follow the duplet rule by gaining or sharing electrons to attain a filled first electron shell containing two electrons, resulting in a stable electron configuration. This stability drives chemical reactivity and bond formation.
