Keshu

Group 16 elements (oxygen, sulfur, selenium, tellurium, polonium) show distinct periodic trends: atomic radius, density, and metallic character increase down the group, while electronegativity, ionization enthalpy, and electron gain enthalpy decrease

Atomic radius is the measure of a neutral atom's size, typically half the distance between nuclei of identical bonded atoms, representing the distance from the nucleus to the outermost electron shell. Ionic radius is the size of an ion (charged atom), measuring the effective distance from the nucleus to the outer electron cloud in a crystal lattice

Electronegativity is the measure of an atom's ability to attract shared electrons in a chemical bond toward itself

In chemistry, a cation is an atom or molecule with a net positive electrical charge, formed when a neutral atom loses one or more electrons, resulting in more protons than electrons

In chemistry, an anion is an atom or molecule that has gained one or more electrons, resulting in a net negative electrical charge because it has more electrons (negative) than protons (positive)

Ionization enthalpy (or energy) is the minimum energy needed to remove the most loosely bound (outermost) electron from a single, isolated gaseous atom, forming a positive ion (cation)

Atomic radius is the measure of an atom's size, defined as the average distance from the center of its nucleus to the outer boundary of its electron cloud, typically measured as half the distance between two bonded atoms of the same element

An isolated gaseous atom is a single atom in the gas phase, far removed from other atoms, meaning there are no significant attractive or repulsive forces influencing it, making it "alone and unperturbed" for precise measurement of properties like ionization energy or electron affinity

Ionic radius is the effective distance from an ion's nucleus to the outer edge of its electron cloud, essentially measuring the size of a charged atom (ion)

Ionization energy (IE) is the minimum energy needed to remove the most loosely bound electron from an isolated, gaseous atom or ion, essentially measuring how strongly an atom holds onto its electrons, with higher values indicating greater stability and lower reactivity. It's a fundamental concept in chemistry, influencing reactivity and bond strength, and generally increases across a period (left to right) and decreases down a group in the periodic table.