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The chemical elements can be broadly divided into metals, metalloids, and nonmetals according to their shared physical and chemical properties.All elemental metals have a shiny appearance (at least when freshly polished); are good conductors of heat and electricity; form alloys with other metallic elements; and have at least one basic oxide.
A mechanical pencil or clutch pencil is a pencil with a replaceable and mechanically extendable solid pigment core called a "lead" / ˈ l ɛ d /. The lead , often made of graphite , is not bonded to the outer casing, and the user can mechanically extend it as its point is worn away from use.
Recognition status, as metalloids, of some elements in the p-block of the periodic table. Percentages are median appearance frequencies in the lists of metalloids. [n 2] The staircase-shaped line is a typical example of the arbitrary metal–nonmetal dividing line found on some periodic tables.
Lead for mechanical pencils Flexible pencils. Mechanical pencils use mechanical methods to push lead through a hole at the end. These can be divided into two groups: with propelling pencils an internal mechanism is employed to push the lead out from an internal compartment, while clutch pencils merely hold the lead in place (the lead is ...
Though often placed at the top of the alkali metal column in the periodic table, hydrogen does not, under ordinary conditions, exhibit the properties of an alkali metal. Instead, it forms diatomic H 2 molecules, similar to halogens and some nonmetals in the second period of the periodic table, such as nitrogen and oxygen.
The solid form has a hexagonal crystalline structure and is soft and easily crushed. Hydrogen is an insulator in all of its forms. It has a high ionisation energy (1312.0 kJ/mol), moderate electron affinity (73 kJ/mol), and moderate electronegativity (2.2). Hydrogen is a poor oxidising agent (H 2 + 2e − → 2H – = –2.25 V at pH 0). Its ...