Fundamentals of Atoms and Bonding

Matter is made of atoms with protons (+), neutrons (0), and electrons (–).

Protons decide the element, electrons decide charge, neutrons change

mass (isotopes). Electrons fill energy levels; when they absorb energy, they jump up and

release light when they fall back. This creates emission spectra, unique to each element.

The periodic table is organized by atomic number. Across a period: atoms get smaller,

IE and EN increase because the nucleus pulls harder. Down a group: atoms get larger,

IE and EN drop due to shielding. Same group = similar valence electrons and similar reactivity.

Ions: Metals lose electrons → cations. Nonmetals gain electrons → anions. Bonding: