The nucleus of the helium atom contains 2 massive, positively charged particles. Thus, Z, the atomic number = 2. Helium is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling and melting point are the lowest among all the elements.
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