Educator

Covalent Bond, Lewis Structures, Molecular Orbitals

• Covalent bond: sharing electron pairs

• Number of valence electrons for atom = Group number

• Octet rule – rule of 8; 8 electrons around main group atoms in molecules except H, two electrons

• Rules for Lewis structures: COUNT valence electrons in molecules; put 2 electrons between bonded atoms; use remaining electrons to get 8 shared by other atoms in lone pairs and/or multiple bonds

• Exceptions to octet rule: Be, B etc. in Groups 1 and 2; third period elements like S, P, can exceed 8.

• Electronegativity: power of atom in a bond to attract electrons

• Electronegativity decreases down a group; increases from left to right along a period

• Bonds can be fully ionic; polar; non-polar

• Overlaps of atomic orbitals can give molecular orbital’s

• Sigma orbitals: cylindrical symmetry around internuclear axis

• Pi orbitals: plane of symmetry between nuclei