Rutherford’s nuclear model of the atom helped explain why atoms of different elements exhibit various keolistravelservices.comical behavior. The identity of an facet is identified by that is atomic number (Z), the number of protons in the cell core of one atom of the element. The atom number is as such different because that each element. The known elements are arranged in bespeak of boosting Z in the periodic table (Figure (PageIndex1)). The rationale because that the peculiar layout of the periodic table is explained later. Each aspect is assigned a distinct one-, two-, or three-letter symbol. The name of the facets are provided in the regular table, in addition to their symbols, atomic numbers, and also atomic masses. The keolistravelservices.comistry that each element is determined by its variety of protons and also electrons. In a neutral atom, the variety of electrons equates to the variety of protons.

You are watching: One of a class of elements having properties intermediate to metals and nonmetals.

Figure (PageIndex1): The periodic Table reflecting the elements in bespeak of increasing Z. The metals are ~ above the bottom left in the periodic table, and the nonmetals are at the optimal right. The semimetals lie follow me a diagonal heat separating the metals and also nonmetals. One interactivePeriodic table have the right to befound here.

The facets are arranged in a routine table, i beg your pardon is more than likely the solitary most essential learning aid in keolistravelservices.comistry. It summarizes vast amounts that information around the facets in a way that facilitates the forecast of numerous of their properties and also keolistravelservices.comical reactions. The elements are i ordered it in seven horizontal rows, in stimulate of boosting atomic number from left to right and top come bottom. The rows are dubbed periods, and also they are numbered native 1 come 7. The elements are stacked in together a method that aspects with comparable keolistravelservices.comical properties form vertical columns, dubbed groups, numbered indigenous 1 come 18 (older routine tables use a system based upon roman numerals). Groups 1, 2, and also 13–18 are the main group elements, noted as A in enlarge tables. Groups 3–12 are in the center of the routine table and also are the shift elements, provided as B in larger tables. The 2 rows of 14 elements at the bottom that the routine table are the lanthanides and the actinides, whose positions in the periodic table are indicated in group 3.


Metals, Nonmetals, and also Semimetals

The hefty orange zigzag line to run diagonally native the top left to the lower right through groups 13–16 in figure (PageIndex1) divides the aspects into metals (in blue, below and also to the left that the line) and also nonmetals (in bronze, above and come the right of the line). Gold-colored lements that lie follow me the diagonal line exhibit nature intermediate between metals and nonmetals; castle are referred to as semimetals.

The difference between metals and nonmetals is just one of the most fundamental in keolistravelservices.comistry. Metals—such together copper or gold—are great conductors of electricity and heat; they deserve to be pulled right into wires because they room ductile; they deserve to be hammered or pressed right into thin sheets or foils due to the fact that they room malleable; and most have a glowing appearance, so they space lustrous. The vast majority of the known facets are metals. That the metals, only mercury is a fluid at room temperature and pressure; all the remainder are solids.

Nonmetals, in contrast, space generally negative conductors that heat and also electricity and are no lustrous. Nonmetals can be gases (such as chlorine), liquids (such as bromine), or solids (such together iodine) at room temperature and pressure. Many solid nonmetals are brittle, therefore they rest into tiny pieces once hit v a hammer or pulled into a wire. As expected, semimetals exhibit properties intermediate in between metals and also nonmetals.


Example (PageIndex1): Classifying Elements

Based on its place in the periodic table, carry out you expect selenium to it is in a metal, a nonmetal, or a semimetal?

Given: element

Asked for: classification

Strategy:

Find selenium in the periodic table shown in number (PageIndex1) and also then share the facet according come its location.

Solution:

The atomic variety of selenium is 34, which locations it in duration 4 and also group 16. In number (PageIndex1), selenium lies above and to the ideal of the diagonal line marking the boundary in between metals and nonmetals, so it should be a nonmetal. Note, however, that because selenium is close come the metal-nonmetal dividing line, it would not be how amazing if selenium were similar to a semimetal in several of its properties.


Exercise (PageIndex1)

Based on its ar in the regular table, perform you expect indium to it is in a nonmetal, a metal, or a semimetal?

Answer

metal


As formerly noted, the regular table is arranged so that aspects with comparable keolistravelservices.comical habits are in the very same group. keolistravelservices.comists regularly make basic statements about the nature of the elements in a group using descriptive surname with historical origins. For example, the aspects of team 1 are known as the alkali metals, team 2 space the alkaline planet metals, group 17 room the halogens, and also Group 18 are the noble gases.


Group 1: The Alkali Metals

The alkali metals are lithium, sodium, potassium, rubidium, cesium, and francium. Hydrogen is distinct in that it is generally placed in group 1, however it is no a metal. The compound of the alkali steels are typical in nature and daily life. One instance is table salt (sodium chloride); lithium link are used in greases, in batteries, and also as drugs to act patients who exhibit manic-depressive, or bipolar, behavior. Back lithium, rubidium, and also cesium are fairly rare in nature, and francium is so unstable and highly radioactive that it exists in just trace amounts, sodium and potassium are the seventh and eighth many abundant facets in Earth’s crust, respectively.


Group 2: The Alkaline earth Metals

The alkaline planet metals room beryllium, magnesium, calcium, strontium, barium, and radium. Beryllium, strontium, and also barium space rare, and also radium is unstable and highly radioactive. In contrast, calcium and magnesium are the fifth and sixth most abundant aspects on Earth, respectively; castle are discovered in substantial deposits of limestone and also other minerals.


Group 17: The Halogens

The halogens are fluorine, chlorine, bromine, iodine, and also astatine. The name halogen is acquired from the Greek words because that “salt forming,” which mirrors that every the halogens react easily with steels to kind compounds, together as sodium chloride and calcium chloride (used in some locations as road salt).

Compounds that contain the fluoride ion are included to toothpaste and the water supply to prevent dental cavities. Fluorine is additionally found in Teflon coatings ~ above kitchen utensils. Back chlorofluorocarbon propellants and also refrigerants are thought to lead to the depletion of Earth’s ozone layer and also contain both fluorine and also chlorine, the last is responsible because that the adverse result on the ozone layer. Bromine and iodine are much less abundant than chlorine, and also astatine is so radioactive the it exists in just negligible amounts in nature.


Group 18: The Noble Gases

The noble gases space helium, neon, argon, krypton, xenon, and radon. Due to the fact that the noble gases space composed that only solitary atoms, castle are referred to as monatomic. In ~ room temperature and pressure, they space unreactive gases. Because of their lack of reactivity, for plenty of years lock were dubbed inert gases or rare gases. However, the very first keolistravelservices.comical link containing the noble gases were prepared in 1962. Return the noble gases are relatively minor ingredient of the atmosphere, natural gas consists of substantial quantities of helium. Since of its low reactivity, argon is regularly used as an unreactive (inert) environment for welding and also in light bulbs. The red light emitted by neon in a gas discharge tube is supplied in neon lights.

The noble gases space unreactive at room temperature and pressure.

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Summary

The periodic table is supplied as a predictive tool. It arranges of the aspects in bespeak of raising atomic number. Elements that exhibit comparable keolistravelservices.comistry show up in vertical columns dubbed groups (numbered 1–18 from left to right); the 7 horizontal rows are called periods. Several of the groups have widely-used usual names, including the alkali metals (Group 1) and the alkaline planet metals (Group 2) top top the much left, and the halogens (Group 17) and also the noble gases (Group 18) ~ above the much right. The elements can be extensively divided right into metals, nonmetals, and semimetals. Semimetals exhibit nature intermediate in between those of metals and also nonmetals. Metals are located on the left that the periodic table, and nonmetals are situated on the upper right. They space separated by a diagonal band of semimetals. Steels are lustrous, great conductors that electricity, and readily shame (they space ductile and also malleable), whereas solid nonmetals are generally brittle and also poor electric conductors. Other essential groupings of facets in the routine table space the main team elements, the change metals, the lanthanides, and the actinides.