Rutherford’s nuclear model of the atom aided explain why atoms of different facets exhilittle bit different slrfc.orgical behavior. The identification of an aspect is identified by its atomic number (Z), the variety of proloads in the nucleus of an atom of the aspect. The atomic number is therefore different for each facet. The recognized facets are arranged in order of increasing Z in the periodic table (Figure (PageIndex1)). The rationale for the strange format of the routine table is explained later on. Each facet is assigned a distinct one-, two-, or three-letter symbol. The names of the facets are detailed in the periodic table, in addition to their symbols, atomic numbers, and atomic masses. The slrfc.orgisattempt of each element is identified by its number of prolots and also electrons. In a neutral atom, the number of electrons equals the number of prolots.

You are watching: Name the three general categories into which the elements are divided.

Figure (PageIndex1): The Periodic Table Showing the Elements in Order of Increasing Z. The steels are on the bottom left in the routine table, and the nonsteels are at the top ideal. The semimetals lie alengthy a diagonal line separating the steels and also nonmetals. An interactivePeriodic table deserve to beuncovered here.

The aspects are arranged in a periodic table, which is most likely the single many crucial discovering help in slrfc.orgistry. It summarizes expensive quantities of indevelopment about the elements in a method that facilitates the prediction of many kind of of their properties and slrfc.orgical reactions. The aspects are arranged in salso horizontal rows, in order of enhancing atomic number from left to best and top to bottom. The rows are called periods, and also they are numbered from 1 to 7. The facets are stacked in such a way that facets through similar slrfc.orgical properties develop vertical columns, referred to as groups, numbered from 1 to 18 (older periodic tables usage a system based upon roguy numerals). Groups 1, 2, and 13–18 are the main team aspects, listed as A in older tables. Groups 3–12 are in the middle of the regular table and also are the change aspects, noted as B in older tables. The 2 rows of 14 aspects at the bottom of the periodic table are the lanthanides and the actinides, whose positions in the regular table are suggested in group 3.

Metals, Nonmetals, and also Semimetals

The hefty oselection zigzag line running diagonally from the top left to the lower right through teams 13–16 in Figure (PageIndex1) divides the aspects into metals (in blue, below and also to the left of the line) and nonsteels (in bronze, over and also to the best of the line). Gold-colored lements that lie along the diagonal line exhilittle properties intermediate between steels and also nonmetals; they are dubbed semimetals.

The distinction in between metals and nonmetals is among the many basic in slrfc.orgistry. Metals—such as copper or gold—are good conductors of electrical power and heat; they have the right to be pulled into wires because they are ductile; they have the right to be hammered or pressed into thin sheets or foils bereason they are malleable; and also most have a shiny appearance, so they are lustrous. The huge majority of the recognized elements are steels. Of the metals, just mercury is a liquid at room temperature and pressure; all the remainder are solids.

Nonmetals, in contrast, are mostly bad conductors of heat and electrical power and also are not lustrous. Nonsteels can be gases (such as chlorine), liquids (such as bromine), or solids (such as iodine) at room temperature and press. Most solid nonmetals are brittle, so they break right into little pieces as soon as hit through a hammer or pulled right into a wire. As supposed, semimetals exhilittle properties intermediate in between steels and nonsteels.

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Exercise (PageIndex1)

Based on its place in the routine table, do you intend indium to be a nonmetal, a steel, or a semimetal?



As formerly detailed, the periodic table is arranged so that elements through comparable slrfc.orgical habits are in the same team. slrfc.orgists often make general statements around the properties of the facets in a team using descriptive names through historical beginnings. For example, the elements of Group 1 are well-known as the alkali steels, Group 2 are the alkaline earth metals, Group 17 are the halogens, and Group 18 are the noble gases.