How many protons and electrons are in an atom of atomic number is 11?

1 Answer
Sep 30, 2016

Answer:

There are #"11 protons"# and #"11 electrons"# in the neutral atom.

Explanation:

The atomic number, #Z#, specifies the number of massive, positively charged particles present in the element's nucleus, and this number defines the identity of the element: #Z=1#, hydrogen, #Z=2#, helium, ...... #Z=6#, carbon........#Z=31#, gallium, etc.

Because elements, (and all matter) are usually neutral entities, if there are #Z# positive charges, there must be #Z# negative charges in the neutral atom. In other words, #Z="number of electrons"# for the neutral element.

If #Z=11#, then what is the element? This element has an atomic mass of #23*"amu"#. How do we account for the mass excess to that of the protons? Certainly electrons don't contribute any mass.