Lewis Structures and Formal Charges

Covalent bond

The type of bond that results from the interactions between the two non-metal atoms.

attraction, atoms, electrons

The mutual __________ of the _____ of these shared _________ holds the two atoms in close proximity in a covalent bond

The outermost s and p sub-shells

Are largely responsible for the formation of the covalent bonds

Valence electrons

Electrons in the outermost s and p sub-shells

1s²2s²2p³

Electronic configuration of a neutral Nitrogen atom.

Lewis Structure

The model where the dots around the symbol represent the valence electrons.

Electrons are arranged singly around the four sides before pairing.

Octet Rule

Atoms often lose, gain, or share electrons so that they end up with the eight valence electrons.

Duet rule

The rule by which the Hydrogen atom abides by (exclusively???)

The special stability of the noble gases or to have eight valence electrons

The octet rule is based on what?

Noble gases

The family of elements in a periodic table that have a full valence shell.

Lone pairs

These are the electrons that belong entirely to one atom.

They are represented by a pair of dots, near the atom.

Bonding pairs

These are the electrons shared between the two atoms.

A line between the atoms represent how a pair of electrons is being shared.

Carbon and Nitrogen

Two elements that have less than 8 electrons around, could have been considered an exception to the octet rule but turns out that they do follow the octet rule.

Helium

An exceptional element that does not follows the octet rule, because it is already stable.

Lithium

An exceptional element that does not follows the octet rule because all it needs to do is to lose 1 electron or need 2 electrons to gain the stability.

Beryllium

An exceptional element that does not follows the octet rule because all it needs to form a stable bond is 4 electrons.

Boron

An exceptional element that does not follows the octet rule because all it needs to form a stable bond is 6 electrons.

Scandium (Z=21)

The first element to start filling the 3d orbital.

Phosphorus (Z = 15)

The first real exception element in periodic table where the element becomes the exception to the octet rule by exceeding the octet rule.

Nonequivalent Lewis structures

Lewis structures with different bonding arrangements.

The formal charge of an atom in the molecule

The difference between the number of valence electrons on the free atom and the no. of valence electrons assigned to the atom in the molecule.

Formal charge = Valence electrons on the free neutral atom - Number of valence electrons assigned to the atom in the molecule

Formula for the formal charge

(Valence electrons)assigned = nonbonding electrons + bonds

Formula for the assigned valence electrons

Atoms in molecules try to achieve formal charge as close as zero and any negative formal charges are expected to reside on the most electronegative atom.

Two criteria on which the evaluation is done after all atoms in each nonequivalent Lewis structure is assigned

standard, stability

Atoms in molecular compounds often group themselves in ________ structures because of the _________ offered by those structures.

Functional group

A specific group of atoms arranged in a particular way within an organic molecule, that gives the molecule its unique chemical properties and reactivity.