Atomic Bonding and Periodic Table Overview

Johan Dobereiner

Grouped elements into triads based on properties.

Lothar Meyer

Organized elements by atomic mass, predicted undiscovered.

Henry Moseley

Organized elements by atomic number instead of mass.

John Newlands

Introduced law of octaves for element properties.

Dmitri Mendeleev

Left gaps for undiscovered elements, arranged by properties.

Octet Rule

Atoms seek 8 electrons for stability.

Groups/Families

Vertical columns with similar properties and valence electrons.

Periods

Horizontal rows indicating increasing energy levels.

Coulombic Attraction

Weakens with distance between protons and electrons.

Shielding

Inner electrons repel outer electrons, reducing attraction.

Atomic Radius

Increases down a group, decreases across a period.

Ionization Energy

Energy required to remove an electron from an atom.

Electronegativity

Increases across a period, decreases down a group.

Alkali Metals

Group 1 elements, 1 valence electron, highly reactive.

Alkaline Earth Metals

Group 2 elements, 2 valence electrons, moderately reactive.

Halogens

Group 17 elements, 7 valence electrons, very reactive.

Noble Gases

Group 18 elements, full valence shell, inert.

Transition Metals

Groups 3-12, exhibit multiple oxidation states.

Lanthanides

4f row elements, rare-earth, highly reactive.

Actinides

5f row elements, radioactive and unstable.

Ionic Bonds

Electrons transferred between atoms with high electronegativity difference.

Covalent Bonds

Electrons shared between atoms; includes polar and non-polar.

Diatomic Molecules

Molecules with two identical atoms, e.g., H₂, O₂.