Period 2 element

A chemical element in the second row of the periodic table, from lithium through neon. These elements fill the 2s and 2p electron shells.

Periodic table: A tabular arrangement of chemical elements ordered by atomic number and recurring chemical properties. Its second row groups these elements as one period.
Periodic trend: A recurring change in an element's properties across a period or down a group of the periodic table. Period 2 displays several major trends over a short sequence.
Lithium: A soft, silvery alkali metal with atomic number 3 and the lightest solid element. It begins Period 2 with one valence electron and strong metallic character.
Period 3 element: A chemical element in the third row of the periodic table, from sodium through argon. Its larger valence shell allows bonding patterns unavailable to Period 2 elements.
Atomic number: The number of protons in an atom's nucleus, which determines the identity of its element. Increasing atomic number from 3 to 10 orders the elements across this period.
Effective nuclear charge: The net positive charge experienced by an electron after shielding by other electrons is considered. It generally rises across Period 2 as proton number increases.
Beryllium: A hard, lightweight alkaline-earth metal with atomic number 4. It illustrates the high charge density and distinctive bonding of an early-row metal.
Group 1 element: An element in the first column of the periodic table, excluding hydrogen in some classifications. Lithium shares this family with heavier alkali metals, whose properties differ down the group.
Electron shell: A group of atomic orbitals with similar energies and principal quantum number. The second shell fills across Period 2.
Atomic radius: A measure of the size of an atom, defined using distances between nuclei in specified chemical environments. It generally contracts from lithium to fluorine as effective nuclear charge rises.

Linked from 1 page