Rutherford’s nuclear design of the atom helped describe why atom of different aspects exhibit different yellowcomic.comical behavior. The identity of an facet is defined by that atomic number (Z), the number of protons in the nucleus of one atom of the element. The atomic number is as such different because that each element. The known aspects are arranged in stimulate of enhancing Z in the periodic table (Figure (PageIndex1)). The rationale for the peculiar format of the periodic table is described later. Each aspect is assigned a unique one-, two-, or three-letter symbol. The names of the elements are noted in the periodic table, in addition to their symbols, atom numbers, and also atomic masses. The yellowcomic.comistry that each element is identified by its number of protons and also electrons. In a neutral atom, the variety of electrons equals the variety of protons.

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Figure (PageIndex1): The routine Table reflecting the facets in stimulate of enhancing Z. The metals are top top the bottom left in the regular table, and also the nonmetals space at the optimal right. The semimetals lie follow me a diagonal line separating the metals and nonmetals. One interactivePeriodic table can befound here.

The facets are arranged in a periodic table, i beg your pardon is probably the solitary most important learning aid in yellowcomic.comistry. The summarizes substantial amounts of information about the elements in a way that facilitates the forecast of numerous of their properties and also yellowcomic.comical reactions. The elements are i ordered it in 7 horizontal rows, in stimulate of raising atomic number native left to right and top come bottom. The rows are dubbed periods, and they are numbered from 1 to 7. The facets are stack in such a method that aspects with comparable yellowcomic.comical properties kind vertical columns, referred to as groups, numbered native 1 come 18 (older regular tables use a system based upon roman numerals). Groups 1, 2, and also 13–18 space the main group elements, detailed as A in enlarge tables. Groups 3–12 space in the center of the routine table and are the change elements, detailed as B in enlarge tables. The two rows the 14 facets at the bottom the the periodic table space the lanthanides and the actinides, whose positions in the periodic table are indicated in team 3.


Metals, Nonmetals, and Semimetals

The hefty orange zigzag line to run diagonally native the upper left to the lower right through teams 13–16 in figure (PageIndex1) divides the facets into metals (in blue, below and also to the left the the line) and also nonmetals (in bronze, over and come the right of the line). Gold-colored lements that lie along the diagonal heat exhibit nature intermediate in between metals and also nonmetals; castle are called semimetals.

The difference between metals and also nonmetals is one of the most basic in yellowcomic.comistry. Metals—such as copper or gold—are great conductors that electricity and also heat; they deserve to be pulled into wires since they room ductile; they deserve to be hammered or pressed into thin sheets or foils because they room malleable; and also most have a glowing appearance, therefore they space lustrous. The vast bulk of the known elements are metals. The the metals, only mercury is a fluid at room temperature and pressure; all the remainder are solids.

Nonmetals, in contrast, room generally negative conductors of heat and also electricity and also are not lustrous. Nonmetals have the right to be gases (such as chlorine), liquids (such as bromine), or solids (such as iodine) in ~ room temperature and pressure. Many solid nonmetals room brittle, therefore they break into small pieces as soon as hit v a hammer or pulled into a wire. Together expected, semimetals exhibit nature intermediate in between metals and also nonmetals.

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Exercise (PageIndex1)

Based top top its ar in the regular table, carry out you suppose indium to be a nonmetal, a metal, or a semimetal?

Answer

metal


As formerly noted, the regular table is i ordered it so that elements with similar yellowcomic.comical habits are in the exact same group. yellowcomic.comists often make general statements around the properties of the elements in a team using descriptive surname with historical origins. Because that example, the elements of group 1 are known as the alkali metals, team 2 space the alkaline earth metals, team 17 room the halogens, and also Group 18 room the noble gases.