(#1) H
Hydrogen
(#2) He
Helium
(#3) Li
Lithium
(#4) Be
Beryllium
(#5) B
Boron
(#6) C
Carbon
(#7) N
Nitrogen
(#8) O
Oxygen
(#9) F
Fluorine
(#10) Ne
Neon
(#11) Na
Sodium
(#12) Mg
Magnesium
(#13) Al
Aluminum
(#14) Si
Silicon
(#15) P
Phosphorus
(#16) S
Sulfur
(#17) Cl
Chlorine
(#18) Ar
Argon
(#19) K
Potassium
(#20) Ca
Calcium