What is the atomic number of an element equal to?

1 Answer
anor277
Jun 24, 2016

The atomic number, #Z#, is equal to the number of protons, positively charged nuclear particles, that reside in the element's nucleus.

Explanation:

#Z=1#, the element is hydrogen, #Z=2#, the element is helium, .....#Z=6#, the element is carbon..........#Z=17#, the element is chlorine.

Now sometimes in chemistry, when we say proton, we mean the #H^+" or "H_3O^+# ion. Here, in the context of atomic physics, we mean a massive, positively charged nuclear particle, whose number defines the identity of the nucleus.

Two questions:

#"Do you have to remember these numbers?"#

#"In the neutral ATOM how many electrons are there compared"# #"to Z?"#

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