He

(a)  

lithium

(a)  

beryllium

(a)  

B

(a)  

carbon

(a)  

nitrogen

(a)  

oxygen

(a)  

F

(a)  

Ne

(a)  

sodium

(a)  

magnesium

(a)  

Al

(a)  

phosphorous

(a)  

silicon

(a)  

S

(a)  

chlorine

(a)  

Ar

(a)  

potassium

(a)  

Ca

(a)  

Ti

(a)  

copper

(a)  

silver

(a)  

Au

(a)  

Pb

(a)  

mercury

(a)  

Sn

(a)  

I

(a)  

Kr

(a)  

Zn

(a)  

nickel

(a)  

Fe

(a)  

Mn

(a)  

xenon

(a)  

radon

(a)  

radium

(a)  

As

(a)  

astatine

(a)  

Ba

(a)  

selenium

(a)