Question

what is a first atoms number​

Answer 1

Answer:

the first atom would be called carbon-12 or 12C

Explanation:

(because it has six protons and six neutrons)

Answer 2

Answer:

The atomic number is the number of protons in the nucleus of an atom. The number of protons define the identity of an element (i.e., an element with 6 protons is a carbon atom, no matter how many neutrons may be present).