Rutherford’s nuclear design of the atom helped explain why atom of different facets exhibit various ubraintv-jp.comical behavior. The identity of an aspect is identified by that atomic number (Z), the variety of protons in the nucleus of one atom the the element. The atomic number is therefore different for each element. The known facets are i ordered it in stimulate of boosting Z in the periodic table (Figure (PageIndex1)). The rationale for the peculiar format of the regular table is explained later. Each aspect is assigned a distinctive one-, two-, or three-letter symbol. The surname of the elements are noted in the regular table, along with their symbols, atom numbers, and atomic masses. The ubraintv-jp.comistry of each element is established by its number of protons and electrons. In a neutral atom, the variety of electrons equates to the variety of protons.

You are watching: Elements on the left side of the periodic table

Figure (PageIndex1): The regular Table reflecting the facets in bespeak of increasing Z. The steels are top top the bottom left in the regular table, and also the nonmetals are at the peak right. The semimetals lie follow me a diagonal heat separating the metals and nonmetals. One interactivePeriodic table can befound here.

The facets are i ordered it in a regular table, i m sorry is most likely the solitary most necessary learning aid in ubraintv-jp.comistry. The summarizes huge amounts of information around the facets in a way that facilitates the prediction of countless of their properties and ubraintv-jp.comical reactions. The aspects are arranged in seven horizontal rows, in bespeak of raising atomic number native left come right and top come bottom. The rows are called periods, and also they are numbered indigenous 1 to 7. The elements are stack in together a method that aspects with similar ubraintv-jp.comical properties form vertical columns, referred to as groups, numbered indigenous 1 come 18 (older periodic tables usage a system based on roman numerals). Teams 1, 2, and also 13–18 room the main group elements, listed as A in older tables. Groups 3–12 room in the middle of the periodic table and also are the shift elements, provided as B in enlarge tables. The 2 rows of 14 facets at the bottom the the regular table space the lanthanides and also the actinides, whose positions in the regular table are shown in team 3.


Metals, Nonmetals, and Semimetals

The heavy orange zigzag line running diagonally indigenous the top left to the reduced right through teams 13–16 in figure (PageIndex1) divides the elements into metals (in blue, below and to the left that the line) and also nonmetals (in bronze, over and to the right of the line). Gold-colored lements that lie follow me the diagonal line exhibit nature intermediate in between metals and also nonmetals; they are called semimetals.

The difference between metals and nonmetals is just one of the most an essential in ubraintv-jp.comistry. Metals—such together copper or gold—are an excellent conductors the electricity and also heat; they can be pulled into wires because they room ductile; they can be hammered or pressed right into thin sheets or foils since they room malleable; and also most have actually a glowing appearance, therefore they space lustrous. The vast bulk of the known aspects are metals. Of the metals, only mercury is a liquid at room temperature and pressure; every the rest are solids.

Nonmetals, in contrast, are generally poor conductors the heat and electricity and are no lustrous. Nonmetals deserve to be gases (such together chlorine), liquids (such together bromine), or solids (such together iodine) in ~ room temperature and pressure. Most solid nonmetals room brittle, therefore they break into little pieces once hit through a hammer or pulled right into a wire. As expected, semimetals exhibit nature intermediate in between metals and nonmetals.


Example (PageIndex1): Classifying Elements

Based top top its position in the periodic table, execute you suppose selenium to be a metal, a nonmetal, or a semimetal?

Given: element

Asked for: classification

Strategy:

Find selenium in the periodic table shown in figure (PageIndex1) and also then divide the facet according to its location.

Solution:

The atomic number of selenium is 34, which locations it in period 4 and group 16. In figure (PageIndex1), selenium lies over and to the right of the diagonal line noting the boundary between metals and nonmetals, therefore it need to be a nonmetal. Note, however, that since selenium is close come the metal-nonmetal separating line, it would not be surprising if selenium were similar to a semimetal in few of its properties.


Exercise (PageIndex1)

Based on its location in the periodic table, carry out you mean indium to it is in a nonmetal, a metal, or a semimetal?

Answer

metal


As previously noted, the periodic table is arranged so that elements with similar ubraintv-jp.comical habits are in the exact same group. ubraintv-jp.comists frequently make general statements about the nature of the elements in a team using descriptive names with historic origins. For example, the facets of group 1 are known as the alkali metals, group 2 room the alkaline planet metals, group 17 are the halogens, and Group 18 room the noble gases.


Group 1: The Alkali Metals

The alkali steels are lithium, sodium, potassium, rubidium, cesium, and francium. Hydrogen is distinctive in the it is generally placed in team 1, yet it is not a metal. The compounds of the alkali steels are common in nature and daily life. One instance is table salt (sodium chloride); lithium compound are used in greases, in batteries, and as drugs to law patients who exhibit manic-depressive, or bipolar, behavior. Back lithium, rubidium, and also cesium are relatively rare in nature, and also francium is therefore unstable and highly radioactive that it exist in just trace amounts, sodium and potassium room the seventh and also eighth many abundant aspects in Earth’s crust, respectively.


Group 2: The Alkaline earth Metals

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


Group 17: The Halogens

The halogens space fluorine, chlorine, bromine, iodine, and also astatine. The surname halogen is derived from the Greek words because that “salt forming,” which shows that all the halogens react easily with steels to form compounds, such as sodium chloride and calcium chloride (used in some locations as roadway salt).

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


Group 18: The Noble Gases

The noble gases are helium, neon, argon, krypton, xenon, and radon. Since the noble gases room composed the only solitary atoms, they are called monatomic. In ~ room temperature and pressure, they space unreactive gases. Because of their lack of reactivity, for numerous years lock were dubbed inert gases or rare gases. However, the very first ubraintv-jp.comical compounds containing the noble gases were ready in 1962. Return the noble gases are relatively minor constituents of the atmosphere, herbal gas contains substantial quantities of helium. Because of its short reactivity, argon is often used together an unreactive (inert) environment for welding and in light bulbs. The red irradiate emitted through neon in a gas discharge tube is supplied in neon lights.

The noble gases space unreactive in ~ room temperature and pressure.

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Summary

The routine table is used as a predictive tool. It arranges the the aspects in stimulate of boosting atomic number. Aspects that exhibit similar ubraintv-jp.comistry appear in vertical columns referred to as groups (numbered 1–18 native left come right); the seven horizontal rows are referred to as periods. Few of the teams have widely-used typical names, consisting of the alkali metals (Group 1) and the alkaline planet metals (Group 2) top top the much left, and also the halogens (Group 17) and the noble gases (Group 18) on the much right. The elements can be generally divided into metals, nonmetals, and semimetals. Semimetals exhibit properties intermediate in between those the metals and nonmetals. Metals are situated on the left the the routine table, and also nonmetals are situated on the top right. They room separated by a diagonal tape of semimetals. Steels are lustrous, an excellent conductors that electricity, and readily shame (they room ductile and malleable), whereas solid nonmetals are normally brittle and also poor electrical conductors. Other crucial groupings of facets in the routine table space the main group elements, the change metals, the lanthanides, and the actinides.