elementary steps

coordination (bond forming)

nucleophile creates a bond with electrophile

heterolysis (bond breaking)

molecular reverse of bond forming, a leaving group leaves (dissociates)

Sn2

Sn1

E2

E1

nucleophilic addition

a nucleophile adds to a polar pi bond (usually a carbonyl)

nucleophilic elimination

the reverse where a leaving group leaves in place of the creation of a new pi bond

electrophilic addition

an electrophilic addition, an electrophile add to non-polar alkenes or polar pi bonds

electrophilic elimination

is the reverse to electrophile addition where a substituent or H that is alpha toa carbocation is eliminated to form a pi bond

tautomerization

when two or more structural isomers (tautomers) interconvert through the rapid relocation of hydrogen atom and migration of the double bond

1, 4 conjugate

is a special type of nucleophile addition to, alpha-beta unsaturated carbonyls