* Atoms are neutral: Atoms have an equal number of protons (positively charged particles) and electrons (negatively charged particles). This balance results in a neutral overall charge.

* Ions are charged: An ion is an atom or molecule that has gained or lost electrons, giving it a net electrical charge.

* Positive ions (cations): When an atom *loses* electrons, it has more protons than electrons. This excess of positive charge makes the atom a positively charged ion, also called a cation.

Example: Sodium (Na) has 11 protons and 11 electrons. When it becomes a positive ion (Na+), it loses one electron, leaving it with 11 protons and 10 electrons, resulting in a +1 charge.

Key takeaways:

* Losing electrons leads to a positive charge.

* The number of protons in an atom determines its atomic number and remains constant.

* The number of electrons changes when an atom forms an ion.