Deca=10
Decades
Decalog
Decagon

Nona=9
nonadult
nonacid
nonagon

Octo=8
Octogon
Octopus
October

hept=7
Heptameter
Heptagon
Heptane

Hex=Six
Hexagon
Hexahydrate
Hexahedrons

penta=five
pentagon
pentarch
repentant

tetra=four
tetragons
tetraploid
tetramer

tri=three
triangle
airstrike
atria

di=two
dictator
abdicate
acidify

mono = one
monopoly
ammono
monohull

Neon Calcium
Ne Ca
10 20

Potassium Fluroine
K F
19 9

Oxygen Argon
O AR
8 18

Nitrogen Chlorine
N CI
7 17
Carbon Sulfur
C S
6 16

Phosphorus Boron
P B
15 5
