And this is something that is non-negotiable. How do I know? Well, I gots me a Periodic Table beside me that clearly tells me the atomic numbers of the 100 or so known elements. The atomic number, #Z#, CLEARLY defines the element...#Z=1,"hydrogen"#; #Z=2,"helium"#;.....#Z=13,"aluminum"#; ....#Z=92,"uranium"#. And if you are doing your chemistry homework there should be a Periodic Table beside you as well.
So what does #Z# mean? It represents the number of protons, positively-charged, massive nucular particles, present in the element's nuclear core. Within the nucleus, there are also neutrons, neutrally-charged, massive nucular particles, which together with the nuclear protons engage in the #"strong nuclear force"#, the which, at impossibly short nuclear ranges, is strong enuff to overcome the electrostatic repulsion that exists between the like-charged protons, and bind the nuclear core together. (Chemists usually take this is read...they deal with electrons, not nuclear interactions...)
A given nucleus can contain various numbers of neutrons, and this gives rise to the phenomenon of #"isotopes"#, elements with the same #Z#, but different numbers of neutrons. Most elements have an envelope of isotopes, and the atomic mass quoted on the Periodic Table is the weighted average of the individual isotopes.
So we were given #""^27Al#, where the superscript is the mass number...and thus there are 13 nuclear protons (by definition!, why so?) AND 14 neutrons. The NEUTRAL atom necessarily contains 13 electrons, extra-nuclear particles of negligible mass that are conceived to whizz about the nuclear core. Loss, gain, or sharing of electrons between atoms, explains ALL of chemistry.
Commonly, aluminum, with 3 valence (i.e. outermost) electrons, loses this set to form the #Al^(3+)# ion.
So that's all of physics and chemistry explained in a couple of paragraphs. Do I win #£5-00#?
