英文關鍵字
covalent
bond
chemical
polarity
atom
atomic
attraction
bonding
carbon
chemist
chemistry
coordinate
diagram
dioxide
double
education
electron
formation
formula
hydrogen
learning
molecular
nitrogen
oxygen
pair
particle
physics
polar
school
science
scientific
sharing
single
structure
symbol
triple
university
valencia
matter
mass
balance
molecule
ionic
theory
quantum