Protons and neutrons are particles that make up the dense nucleus at the center of an atom. Protons have a positive electric charge, and neutrons have no electric charge (i.e., neutrons are electrically neutral).
Electrons are particles that are found surrounding the nucleus; electrons have a negative electric charge.
The magnitude of a proton's positive charge and an electron's negative charge are equal in magnitude. All they differ in is in their polarity.
So, an atom that has the same number of protons and electrons would be electrically neutral. An ion is an atom that has a non-neutral charge because of an imbalance between the number of protons and electrons. If there are more electrons than protons, there is a net negative charge, and this type of ion is called an anion; if there are fewer electrons than protons, there is a net positive charge, and this type of ion is called a cation.
In this case, we have an element (or, more precisely, an atom of an element) that has 35 protons, 36 electrons, and 45 neutrons. There is one more electron than there are protons. This is called an <u>anion</u> because there are <u>fewer</u> electrons compared to protons.
