Colored pencil Colored pencil A colored pencil (US-English), coloured pencil (UK-English, Canada-English), pencil crayon (UK-English, Canada-English), lead or coloured/colouring lead (Newfoundland-English) is an art medium constructed of a narrow, pigmented core encased in a wooden cylindrical case. Unlike graphite and charcoal pencils, colored pencils’ cores are wax- or oil-based and contain varying proportions of pigments, additives, and binding agents. Water-soluble (watercolor) pencils and pastel pencils are also manufactured as well as colored leads for mechanical pencils. Colored pencils vary greatly in terms of quality and usability; concentration of pigments in the core, lightfastness of the pigments, durability of the colored pencil, and
Lead of lead exceeds that of tin, contrary to what periodic trends would predict. Relativistic effects, which become significant in heavier atoms, contribute to this behavior. One such effect is the inert pair effect: the 6s electrons of lead become reluctant to participate in bonding, making the distance between nearest atoms in crystalline lead unusually long. Lead's lighter carbon group congeners form stable or metastable allotropes with the tetrahedrally coordinated and covalently bonded diamond cubic structure. The energy levels of their outer s- and p-orbitals are close enough to allow mixing into four hybrid sp orbitals. In lead, the inert pair