abstract
atoms
black
bohr model
bond
bonding
calcium
carbon
chart
chemical
chemistry
chlorine
circle
class
class 7
class 8
class 9
compound
diagram
dots
education
electron
electrons
elements
energy
formation
formula
hydrogen
illustration
infographic
ion
learn
lewis
model
molecular
molecule
nitrogen
orbitals
particle
represent
science
share
shell
structure
substance
table
valence
valence electrons