Tom balonları helyumla doldurdu.
- Tom filled the balloons with helium.
Helyum, neon, argon, kripton, ksenon ve radon soy gazlardır.
- Helium, neon, argon, krypton, xenon and radon are noble gases.
... They fuse hydrogen into helium, helium into lithium, ...
... hydrogen atoms slam together, creating a new element, helium, ...