compiled by: suprapto van plaosan

A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds.

Key Points

• Valence bond and molecular orbital theories are used to explain chemical bonding.
• Two atoms that have unpaired electrons in their orbitals can overlap to give rise to a chemical bond.
  • A sigma bond (σ) forms when two atomic orbitals overlap between the nuclei of two atoms (also known as the internuclear axis ).
  • Pi bonds (π) occur when two atomic orbitals overlap outside of the space between the nuclei (outside of the internuclear axis).
• The strongest bonds form with maximum overlap between orbitals.

Key Terms

• covalent bond: a chemical bond that is formed from the sharing of two electrons between two atoms.
• internuclear axis: The space between the nuclei of two atoms bonded to each other.
• atomic orbitals: the physical region or space where an electron may be present or found, with a probability calculated from the precise mathematical form of the orbital.
• valence bond theory: a covalent bond forms between the two atoms by the overlap of half-filled valence atomic orbitals from each atom.

σ Bond Formation: Atomic orbitals from two atoms overlap in the region between the nuclei (internuclear axis). Therefore, the resulting electron density of the shared electrons lies in the red region shown in the image.

π Bond Formation: Two unhybridized p-orbitals can overlap so that the electron density of the shared electron pair is described by the π bond depicted on the right.

https://courses.lumenlearning.com/boundless-chemistry/chapter/valence-bond-theory/

Covalent

Strong bond, Two atoms share electrons.ex: Bonding of Oxygen and Hydrogen in H2O

Ionic

Moderate bond, Oppositely charged ions are attracted to each other.Ex. Bond between Na+ and Cl- in salt.

Hydrogen

Weak bond Forms between oppositely charges portions of covalently bonded hydrogen atoms.Ex. Bonds between water molecules.

Hybridization

Key Points¶

• The bonds in a methane (CH4) molecule are formed by four separate but equivalent orbitals; a single 2s and three 2p orbitals of the carbon hybridize into four sp3 orbitals.
• In the ammonia molecule (NH3), 2s and 2p orbitals create four sp3 hybrid orbitals, one of which is occupied by a lone pair of electrons.
• In a water molecule, two sp3 hybrid orbitals are occupied by the two lone pairs on the oxygen atom, while the other two bond with hydrogen.

Key Terms

• tetravalent: having a valence of 4

Boron configuration diagram: One of the three boron electrons is unpaired in its ground state. The atomic s- and p-orbitals in boron’s outer shell mix to form three equivalent hybrid orbitals. These particular orbitals are called sp2 hybrids, meaning that this set of orbitals derives from one s- orbital and two p-orbitals of the free atom.

Formal Charge

http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch01/ch1-3-2.html

How to Calculate Steric Number

https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Book%3A_Introduction_to_Inorganic_Chemistry/01%3A_Review_of_Chemical_Bonding/1.03%3A_The_Shapes_of_Molecules_(VSEPR_Theory)_and_Orbital_Hybridization

Steric Number dan Geometri Molekul

http://www.chem.ucla.edu/~harding/IGOC/S/steric_number.html