Honors Chemistry Chapter 8 - Covalent Bonding

three types of chemical bonds

ionic compounds, metallic bonds, covalent bonds

ionic compounds

form from the transfer of electrons from metal atoms to nonmetal atoms

metallic bonds

form between atoms of the same metallic element or between alloys

covalent bonds

form between atoms that share electrons as nonmetals

how covalent bonds result

when the electronegativity difference between two elements is extremely low

single covalent bond

contains two electrons that are shared between both atoms

duet rule

Hydrogen is one electron away from achieving a helium-like noble gas configuration. Therefore, it will never have more than two valence electrons when it forms covalent bonds.

molecules

groups of two or more atoms held together by covalent bonds

diatomic molecules

molecules made up of two atoms

elements on the periodic table that form diatomic molecules

hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, iodine

cause of a covalent bond

the constructive overlap of orbitals

what happens when two atoms are too close

the nuclei of the two atoms will repel each other

what happens when two atoms are too far away from each other

their orbitals will not overlap in a way to lower potential energy

bond length

the distance where the overlap of orbitals occurs in such a way to lower potential energy as much as possible

sigma bonds

the first type of overlap that can occur

overlap of sigma bonds

direct, head-to-head

pi bonds

covalent bonds that occur between p-orbitals that cannot overlap directly

overlap of pi-bonds

indirect, side-to-side

double bonds

consist of two pairs of shared electrons

composition of double bonds

one sigma bond, one pi bond

triple bonds

three pairs of shared electrons

composition of triple bonds

one sigma bond, two pi bonds

strength of covalent bonds

the more orbital overlap that occurs, he stronger the covalent bond

distance of covalent bonds

the more overlap that occurs, the less distance between the two nuclei

what is required to break a covalent bond

energy (endothermic process)

what happens to energy if a covalent bond is formed

potential energy is lowered and energy is released

melting point of molecular compounds

low

boiling point of molecular compounds

low

why melting and boiling point of molecular compounds are low

molecules are not attracted to other molecules with a strong force of attraction

hardness of molecular compounds

low

conductivity of molecular compounds

do not conduct electricity

electrolyte

a substance that carries an electric charge in water