Atomic Radius Definition: The distance from the center of an atoms nucleus to it’s outermost electron Radius decreases across a period Measure of atomic size Radius increases down a group Each row on the periodic table adds a “shell” or energy level to the atom

Table of Atomic Radii

Electronegativity Definition: A measure of the ability of an atom in a chemical compound to attract electrons Electronegativity tends to increase across a period As radius decreases, electrons get closer to the bonding atom’s nucleus Electronegativity tends to decrease down a group or remain the same As radius increases, electrons are farther from the bonding atom’s nucleus

Periodic Table of Electronegativities

Reactivity Definition: how likely or vigorously an atom is to react with other substances. Metals Period - reactivity decreases as you go from left to right across a period. Group - reactivity increases as you go down a group Why? The farther to the left and down the periodic chart you go, the easier it is for electrons to be given or taken away, resulting in higher reactivity. Non-metals Period - reactivity increases as you go from the left to the right across a period. Group - reactivity decreases as you go down the group. Why? The farther right and up you go on the periodic table, the higher the electronegativity, resulting in a more vigorous exchange of electron.

Reactivity Exception Noble Gases Noble gases are not reactive (inert) because they have a full valence shell. This means they cannot donate, or accept electrons in a chemical reaction. They can, however, bond with other noble gases.

Period Trend: Atomic Radius

Periodic Trend: Electronegativity

Periodic Trend: Reactivity Reactivity decreases (metals) Reactivity increases (nonmetals) Periodic Trend: Reactivity Reactivity decreases (non metals Reactivity increases (Metals) IMPORTANT: Noble Gases NOT reactive (inert)