What is the atomic number of an element defined as?

1 Answer
Feb 16, 2017

#"The atomic number, Z........"#

Explanation:

#"The atomic number, Z,"# is the number of protons, massive, positively charged, present in the nucleus. #Z# defines the identity of the element: #Z=1,"hydrogen";Z=2,"helium";Z=3,"lithium";#
#.................Z=23, "vanadium"#.

From where am I getting these numbers? Do you have to learn them?