Question

Atomic mass of first 40 elements rounded

Answer 1

Here is your answer

The atomic mass is usually a decimal number. When determining the number of neutrons, round the atomic mass to the nearest whole number. For example:Since 2+2=4, we know that the mass number of the helium atom is 4. Finally, the helium atom also contains two electrons, since the number of electrons must equal the number of protons.

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Mass Number.

Name helium

Symbol He

Neutrons 2

Electrons 2

Mass Number (A) (rounded to two decimals) 4.00