Atomic Structure and Ionization Study Notes

Multiple choice problem screen regarding charged atomic particles

Neutral Atoms vs. Charged Particles:
- A neutral atom possesses an equal number of positively charged protons ( $+1$ relative charge) in its nucleus and negatively charged electrons ( $-1$ relative charge) in its electron shells. Consequently, the net electrical charge of a neutral atom is zero ( $0$ ).
- When an atom gains or loses electrons, the balance between protons and electrons is disrupted, converting the neutral atom into a charged particle known as an ion.
Classification of Ions:
- Cations (Positively Charged Ions):
- Formed when an atom loses one or more electrons.
- Because the number of protons exceeds the number of electrons, the overall net charge becomes positive.
- Commonly formed by metallic elements (e.g., sodium losing an electron to form a sodium cation: $Na \rightarrow Na^+ + e^-$ ).
- Anions (Negatively Charged Ions):
- Formed when an atom gains one or more electrons.
- Because the number of electrons exceeds the number of protons, the overall net charge becomes negative.
- Commonly formed by non-metallic elements (e.g., chlorine gaining an electron to form a chloride anion: $Cl + e^- \rightarrow Cl^-$ ).

Molecules:
- A molecule is an electrically neutral group of two or more atoms bound together by chemical bonds (such as covalent bonds).
- Unlike ions, molecules do not specifically refer to atoms that have gained or lost electrons to acquire a net overall charge, although polyatomic ions can exist when a molecular group carries a net charge.
Isotopes:
- Isotopes are variants of a particular chemical element that share the same atomic number (same number of protons) but differ in nucleon count due to having different numbers of neutrons in their nuclei.
- Isotope variations alter atomic mass and nuclear stability, but do not alter the electron count or the chemical charge of a neutral atom.
Radioactive Atoms and Unstable Atoms:
- Radioactive Atoms (Radionuclides): Atoms with unstable nuclei that undergo spontaneous decay, emitting ionizing radiation (such as alpha particles, beta particles, or gamma rays) to achieve a lower energy configuration.
- Unstable Atoms: Refers to atoms with unfavorable proton-to-neutron ratios or excessive nuclear energy.
- Both concepts relate directly to the stability of the atomic nucleus rather than the gain or loss of orbital shell electrons that dictates ionization.