Period 3 element - wikipedia Period 3 element Period 3 in the periodic table Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury ( element ) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Part of a series on the Periodic table Periodic table forms 18 - column large cells 32 - column ( large cells ) Alternative forms Chemical Galaxy Janet 's left step Beyond period 7 Fricke large cells Pyykkö Periodic table history Dmitri Mendeleev predictions Discovery of elements Naming & etymology for places for scientists controversies ( in East Asia ) Systematic element names Sets of elements By periodic table structure Groups ( 1 -- 18 ) 1 ( alkali metals ) 2 ( alkaline earth metals ) 5 6 7 8 9 10 11 12 13 14 15 ( pnictogens ) 16 ( chalcogens ) 17 ( halogens ) 18 ( noble gases ) Periods ( 1 -- 7... ) 5 6 7 8 + Aufbau Fricke Pyykkö Blocks ( s, p, d, f,... ) Atomic orbitals Aufbau principle By metallic classification Metals alkali alkaline earth transition post-transition lanthanide actinide ( super - / eka - super - ) Metalloids dividing metals & nonmetals Nonmetals polyatomic diatomic monatomic ( noble gas ) By other characteristics Coinage metals Platinum - group metals Precious metals Refractory metals Heavy metals Light metals Native metals Noble metals Main - group elements Rare - earth elements Transuranium, transplutonium elements Major, minor & trans - actinides Elements List of chemical elements... by abundance ( in human body ) by atomic properties by isotope stability by annual production by symbol Properties of elements Atomic weight Crystal structure Electron affinity configuration Electronegativity ( ( Allen ) ) ( ( Pauling ) ) Goldschmidt classification Nutrition Valence Data pages for elements Abundance Atomic radius Boiling point Critical point Density Elasticity Electrical resistivity Electron affinity / configuration Electronegativity Hardness Heat capacity / of fusion / of vaporization Ionization energy Melting point Oxidation state Speed of sound Thermal conductivity / expansion coefficient Vapor pressure Book Category Chemistry Portal A period 3 element is one of the chemical elements in the third row ( or period ) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring ( periodic ) trends in the chemical behaviour of the elements as their atomic number increases : a new row is begun when the periodic table skips a row and a chemical behaviour begins to repeat, meaning that elements with similar behavior fall into the same vertical columns. The third period contains eight elements : sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine, and argon. The first two, sodium and magnesium, are members of the s - block of the periodic table, while the others are members of the p - block. Note that there is a 3d subshell, but it is not filled until period 4, such giving the period table its characteristic shape of `` two rows at a time ''. All of the period 3 elements occur in nature and have at least one stable isotope. Contents 1 Periodic trends 1.1 Atomic radius 1.2 Electronegativity 1.3 Ionization energy 2 Elements 2.1 Sodium 2.2 Magnesium 2.3 Aluminium 2.4 Silicon 2.5 Phosphorus 2.6 Sulfur 2.7 Chlorine 2.8 Argon 3 Biological role 4 Table of elements 5 References Periodic trends Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Atomic radius Calculated period 3 atomic radii in picometers. Main article : Atomic radius As the atomic number of elements in Period 3 increases, the atomic radius decreases. Electronegativity Main article : Electronegativity As the atomic mass of elements in Period 3 increases, the electronegativity increases. Ionization energy Main article : Ionization energy As the atomic number of elements in Period 3 increases, the amount of energy required to remove its electrons ( Ionization energy ) increases. Elements Chemical element Chemical series Electron configuration 11 Na Sodium Alkali metal ( Ne ) 3s 12 Mg Magnesium Alkaline earth metal ( Ne ) 3s 13 Al Aluminium Post-transition metal ( Ne ) 3s 3p 14 Si Silicon Metalloid ( Ne ) 3s 3p 15 Phosphorus Polyatomic nonmetal ( Ne ) 3s 3p 16 Sulfur Polyatomic nonmetal ( Ne ) 3s 3p 17 Cl Chlorine Diatomic nonmetal ( Ne ) 3s 3p 18 Ar Argon Noble gas ( Ne ) 3s 3p Sodium Main article : Sodium Sodium ( symbol Na ) is a soft, silvery - white, highly reactive metal and is a member of the alkali metals ; its only stable isotope is Na. It is an abundant element that exists in numerous minerals such as feldspars, sodalite and rock salt. Many salts of sodium are highly soluble in water and are thus present in significant quantities in the Earth 's bodies of water, most abundantly in the oceans as sodium chloride. Many sodium compounds are useful, such as sodium hydroxide ( lye ) for soapmaking, and sodium chloride for use as a deicing agent and a nutrient. The free metal, elemental sodium, does not occur in nature but must be prepared from sodium compounds. Elemental sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. The same ion is also a component of many minerals, such as sodium nitrate. Magnesium Main article : Magnesium Magnesium ( symbol Mg ) is an alkaline earth metal and has common oxidation number + 2. It is the eighth most abundant element in the Earth 's crust and ninth in the known universe as a whole. Magnesium is the fourth most common element in the Earth as a whole ( behind iron, oxygen and silicon ), making up 13 % of the planet 's mass and a large fraction of planet 's mantle. The relative abundance of magnesium is related to the fact that it is easily built up in supernova stars from a sequential addition of three helium nuclei to carbon ( which in turn is made from three helium nuclei ). Due to magnesium ion 's high solubility in water, it is the third most abundant element dissolved in seawater. The free element ( metal ) is not found naturally on Earth, as it is highly reactive ( though once produced, it is coated in a thin layer of oxide ( see passivation ), which partly masks this reactivity ). The free metal burns with a characteristic brilliant white light, making it a useful ingredient in flares. The metal is now mainly obtained by electrolysis of magnesium salts obtained from brine. Commercially, the chief use for the metal is as an alloying agent to make aluminium - magnesium alloys, sometimes called `` magnalium '' or `` magnelium ''. Since magnesium is less dense than aluminium, these alloys are prized for their relative lightness and strength. Magnesium ions are sour to the taste, and in low concentrations help to impart a natural tartness to fresh mineral waters. Aluminium Main article : Aluminium Aluminium ( symbol Al ) or aluminum ( American English ) is a silvery white member of the boron group of chemical elements and a post-transition metal. It is not soluble in water under normal circumstances. Aluminium is the third most abundant element ( after oxygen and silicon ), and the most abundant metal, in the Earth 's crust. It makes up about 8 % by weight of the Earth 's solid surface. Aluminium metal is too reactive chemically to occur natively. Instead, it is found combined in over 270 different minerals. The chief ore of aluminium is bauxite. Aluminium is remarkable for the metal 's low density and for its ability to resist corrosion due to the phenomenon of passivation. Structural components made from aluminium and its alloys are vital to the aerospace industry and are important in other areas of transportation and structural materials. The most useful compounds of aluminium, at least on a weight basis, are the oxides and sulfates. Silicon Main article : Silicon Silicon ( symbol Si ) is a tetravalent metalloid. It is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table. Controversy about silicon 's character dates to its discovery : silicon was first prepared and characterized in pure form in 1824, and given the name silicium ( from Latin : silicis, flints ), with an - ium word - ending to suggest a metal. However, its final name, suggested in 1831, reflects the more physically similar elements carbon and boron. Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure free element in nature. It is most widely distributed in dusts, sands, planetoids, and planets as various forms of silicon dioxide ( silica ) or silicates. Over 90 % of the Earth 's crust is composed of silicate minerals, making silicon the second most abundant element in the earth 's crust ( about 28 % by mass ) after oxygen. Most silicon is used commercially without being separated, and indeed often with little processing of compounds from nature. These include direct industrial building - use of clays, silica sand and stone. Silica is used in ceramic brick. Silicate goes into Portland cement for mortar and stucco, and when combined with silica sand and gravel, to make concrete. Silicates are also in whiteware ceramics such as porcelain, and in traditional quartz - based soda - lime glass. More modern silicon compounds such as silicon carbide form abrasives and high - strength ceramics. Silicon is the basis of the ubiquitous synthetic silicon - based polymers called silicones. Elemental silicon also has a large impact on the modern world economy. Although most free silicon is used in the steel refining, aluminum - casting, and fine chemical industries ( often to make fumed silica ), the relatively small portion of very highly purified silicon that is used in semiconductor electronics ( < 10 % ) is perhaps even more critical. Because of wide use of silicon in integrated circuits, the basis of most computers, a great deal of modern technology depends on it. Phosphorus Main article : Phosphorus Phosphorus ( symbol P ) is a multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks. Elemental phosphorus exists in two major forms -- white phosphorus and red phosphorus -- but due to its high reactivity, phosphorus is never found as a free element on Earth. The first form of elemental phosphorus to be produced ( white phosphorus, in 1669 ) emits a faint glow upon exposure to oxygen -- hence its name given from Greek mythology, Φωσφόρος meaning `` light - bearer '' ( Latin Lucifer ), referring to the `` Morning Star '', the planet Venus. Although the term `` phosphorescence '', meaning glow after illumination, derives from this property of phosphorus, the glow of phosphorus originates from oxidation of the white ( but not red ) phosphorus and should be called chemiluminescence. It is also the lightest element to easily produce stable exceptions to the octet rule. The vast majority of phosphorus compounds are consumed as fertilizers. Other applications include the role of organophosphorus compounds in detergents, pesticides and nerve agents, and matches. Sulfur Main article : Sulfur Sulfur ( symbol S ) is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S. Elemental sulfur is a bright yellow crystalline solid when at room temperature. Chemically, sulfur can react as either an oxidant or reducing agent. It oxidizes most metals and several nonmetals, including carbon, which leads to its negative charge in most organosulfur compounds, but it reduces several strong oxidants, such as oxygen and fluorine. In nature, sulfur can be found as the pure element and as sulfide and sulfate minerals. Elemental sulfur crystals are commonly sought after by mineral collectors for their brightly colored polyhedron shapes. Being abundant in native form, sulfur was known in ancient times, mentioned for its uses in ancient Greece, China and Egypt. Sulfur fumes were used as fumigants, and sulfur - containing medicinal mixtures were used as balms and antiparasitics. Sulfur is referenced in the Bible as brimstone in English, with this name still used in several nonscientific terms. Sulfur was considered important enough to receive its own alchemical symbol. It was needed to make the best quality of black gunpowder, and the bright yellow powder was hypothesized by alchemists to contain some of the properties of gold, which they sought to synthesize from it. In 1777, Antoine Lavoisier helped convince the scientific community that sulfur was a basic element, rather than a compound. Elemental sulfur was once extracted from salt domes where it sometimes occurs in nearly pure form, but this method has been obsolete since the late 20th century. Today, almost all elemental sulfur is produced as a byproduct of removing sulfur - containing contaminants from natural gas and petroleum. The element 's commercial uses are primarily in fertilizers, because of the relatively high requirement of plants for it, and in the manufacture of sulfuric acid, a primary industrial chemical. Other well - known uses for the element are in matches, insecticides and fungicides. Many sulfur compounds are odiferous, and the smell of odorized natural gas, skunk scent, grapefruit, and garlic is due to sulfur compounds. Hydrogen sulfide produced by living organisms imparts the characteristic odor to rotting eggs and other biological processes. Chlorine Main article : Chlorine Chlorine ( symbol Cl ) is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine. It has the highest electron affinity and the third highest electronegativity of all the elements ; for this reason, chlorine is a strong oxidizing agent. The most common compound of chlorine, sodium chloride, has been known since ancient times ; however, around 1630, chlorine gas was obtained by the Belgian chemist and physician Jan Baptist van Helmont. The synthesis and characterization of elemental chlorine occurred in 1774 by Swedish chemist Carl Wilhelm Scheele, who called it `` dephlogisticated muriatic acid air, '' having thought he synthesized the oxide obtained from the hydrochloric acid, because acids were thought at the time to necessarily contain oxygen, a number of chemists, including Claude Berthollet, suggested that Scheele 's dephlogisticated muriatic acid air must be a combination of oxygen and the yet undiscovered element, and Scheele named the supposed new element within this oxide as muriaticum. The suggestion that this newly discovered gas was a simple element was made in 1809 by Joseph Louis Gay - Lussac and Louis - Jacques. This was confirmed by Sir Humphry Davy in 1810, who named it chlorine, from the Greek word χλωρος ( chlōros ), meaning `` green - yellow. '' Chlorine is a component of various compounds, including table salt. It is the second most abundant halogen and 21st most abundant chemical element in Earth 's crust. The great oxidizing potential of chlorine led it to its bleaching and disinfectant uses, as well as uses of an essential reagent in the chemical industry. As a common disinfectant, chlorine compounds are used in swimming pools to keep them clean and sanitary. In the upper atmosphere, chlorine - containing molecules such as chlorofluorocarbons have been implicated in ozone depletion. Argon Main article : Argon Argon ( symbol Ar ) is the third element in group 18 of the periodic table ( the noble gases ). Argon is the third most common gas in the Earth 's atmosphere, at 0.93 %, making it more common than carbon dioxide. Nearly all of this argon is radiogenic argon - 40 derived from the decay of potassium - 40 in the Earth 's crust. In the universe, argon - 36 is by far the most common argon isotope, being the preferred argon isotope produced by stellar nucleosynthesis in supernovas. The name `` argon '' is derived from the Greek word αργον meaning `` lazy '' or `` the inactive one '', a reference to the fact that the element undergoes almost no chemical reactions. The complete octet ( eight electrons ) in the outer atomic shell makes argon stable and resistant to bonding with other elements. Its triple point temperature of 83.8058 K is a defining fixed point in the International Temperature Scale of 1990. Argon is produced industrially by the fractional distillation of liquid air. Argon is mostly used as an inert shielding gas in welding and other high - temperature industrial processes where ordinarily non-reactive substances become reactive ; for example, an argon atmosphere is used in graphite electric furnaces to prevent the graphite from burning. Argon gas also has uses in incandescent and fluorescent lighting, and other types of gas discharge tubes. Argon makes a distinctive blue - green gas laser. Biological role Sodium is an essential element for all animals and some plants. In animals, sodium ions are used against potassium ions to build up charges on cell membranes, allowing transmission of nerve impulses when the charge is dissipated ; it is therefore classified as a dietary inorganic macromineral. Magnesium is the eleventh most abundant element by mass in the human body ; its ions are essential to all living cells, where they play a major role in manipulating important biological polyphosphate compounds like ATP, DNA, and RNA. Hundreds of enzymes thus require magnesium ions to function. Magnesium is also the metallic ion at the center of chlorophyll, and is thus a common additive to fertilizers. Magnesium compounds are used medicinally as common laxatives, antacids ( e.g., milk of magnesia ), and in a number of situations where stabilization of abnormal nerve excitation and blood vessel spasm is required ( e.g., to treat eclampsia ). Despite its prevalence in the environment, aluminium salts are not known to be used by any form of life. In keeping with its pervasiveness, it is well tolerated by plants and animals. Because of their prevalence, potential beneficial ( or otherwise ) biological roles of aluminium compounds are of continuing interest. Silicon is an essential element in biology, although only tiny traces of it appear to be required by animals, however various sea sponges need silicon in order to have structure. It is much more important to the metabolism of plants, particularly many grasses, and silicic acid ( a type of silica ) forms the basis of the striking array of protective shells of the microscopic diatoms. Phosphorus is essential for life. As phosphate, it is a component of DNA, RNA, ATP, and also the phospholipids that form all cell membranes. Demonstrating the link between phosphorus and life, elemental phosphorus was historically first isolated from human urine, and bone ash was an important early phosphate source. Phosphate minerals are fossils. Low phosphate levels are an important limit to growth in some aquatic systems. Today, the most important commercial use of phosphorus - based chemicals is the production of fertilizers, to replace the phosphorus that plants remove from the soil. Sulfur is an essential element for all life, and is widely used in biochemical processes. In metabolic reactions, sulfur compounds serve as both fuels and respiratory ( oxygen - replacing ) materials for simple organisms. Sulfur in organic form is present in the vitamins biotin and thiamine, the latter being named for the Greek word for sulfur. Sulfur is an important part of many enzymes and in antioxidant molecules like glutathione and thioredoxin. Organically bonded sulfur is a component of all proteins, as the amino acids cysteine and methionine. Disulfide bonds are largely responsible for the mechanical strength and insolubility of the protein keratin, found in outer skin, hair, and feathers, and the element contributes to their pungent odor when burned. Elemental chlorine is extremely dangerous and poisonous for all lifeforms, and is used as a pulmonary agent in chemical warfare ; however, chlorine is necessary to most forms of life, including humans, in form of chloride ions. Argon has no biological role. Like any gas besides oxygen, argon is an asphyxiant. Table of elements Period 3 in the periodic table 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Group → ↓ Period Sodium 11 Na Magnesium 12 Mg Aluminium 13 Al Silicon 14 Si Phosphorus 15 P Sulfur 16 S Chlorine 17 Cl Argon 18 Ar black = solid green = liquid red = gas gray = unknown Color of the atomic number shows state of matter ( at 0 ° C and 1 atm ) Primordial From decay Synthetic Border shows natural occurrence of the element Background color shows subcategory in the metal -- metalloid -- nonmetal trend : Metal Metalloid Nonmetal Alkali metal Alkaline earth metal Lanthanide Actinide Transition metal Post - ​ transition metal Polyatomic nonmetal Diatomic nonmetal Noble gas References Jump up ^ Period 3 Element from Scienceaid.co.uk Jump up ^ `` Abundance and form of the most abundant elements in Earth 's continental crust '' ( PDF ). Retrieved 2008 - 02 - 15. Jump up ^ Housecroft, C.E. ; Sharpe, A.G. ( 2008 ). Inorganic Chemistry ( 3rd ed. ). Prentice Hall. pp. 305 -- 306. ISBN 978 - 0131755536. Jump up ^ Ash, Russell ( 2005 ). The Top 10 of Everything 2006 : The Ultimate Book of Lists. Dk Pub. ISBN 0 - 7566 - 1321 - 3. Jump up ^ Anthoni, J Floor ( 2006 ). `` The chemical composition of seawater ''. Jump up ^ Shakhashiri, Bassam Z. `` Chemical of the Week : Aluminum ''. Science is Fun. Retrieved 2007 - 08 - 28. Jump up ^ Nave, R. Abundances of the Elements in the Earth 's Crust, Georgia State University Jump up ^ Herbert Diskowski, Thomas Hofmann `` Phosphorus '' in Ullmann 's Encyclopedia of Industrial Chemistry 2005, Wiley - VCH, Weinheim. doi : 10.1002 / 14356007. a19_505 Jump up ^ Greenwood, N.N. ; & Earnshaw, A. ( 1997 ). Chemistry of the Elements ( 2nd Edn. ), Oxford : Butterworth - Heinemann. ISBN 0 - 7506 - 3365 - 4. Jump up ^ `` Magnesium in health ''. Jump up ^ Aluminum Compounds, Inorganic. doi : 10.1002 / 14356007. a01_527. pub2. Jump up ^ Nielsen, Forrest H. ( 1984 ). `` Ultratrace Elements in Nutrition ''. Annual Review of Nutrition. 4 : 21 -- 41. doi : 10.1146 / annurev. nu. 04.070184. 000321. PMID 6087860. Periodic table Periodic table forms Standard 18 - column 18 - column, large cells 32 - column, large cells Alternative Alternatives Chemical Galaxy Janet 's left step table Extended Extension beyond the 7th period Fricke model large cells Pyykkö model Sets of elements By periodic table structure Groups 1 ( Alkali metals ) 2 ( Alkaline earth metals ) 5 6 7 8 9 10 11 12 13 14 15 ( Pnictogens ) 16 ( Chalcogens ) 17 ( Halogens ) 18 ( Noble gases ) Periods 5 6 7 8 + Aufbau Fricke Pyykkö Blocks s - block p - block d - block f - block g - block Aufbau principle By metallicity Metals Alkali metals Alkaline earth metals Lanthanides Actinides Superactinides Eka - superactinides Transition metals Post-transition metals Metalloids Lists of metalloids by source Dividing line Nonmetals Polyatomic nonmetals Diatomic nonmetals Noble gases Other sets Nutritional elements Platinum - group metals ( PGM ) Rare - earth elements Refractory metals Precious metals Coinage metals Noble metal Heavy metals Native metals Transuranium elements Transactinide elements Major actinides Minor actinides Elements Lists By : Abundance ( in humans ) Atomic properties Nuclear stability Production Symbol Properties Atomic weight Crystal structure Electron affinity Electron configuration Electronegativity Allen Pauling Goldschmidt classification Maximum valence Data pages Abundance Atomic radius Boiling point Critical point Density Elasticity Electrical resistivity Electron affinity Electron configuration Electronegativity Hardness Heat capacity Heat of fusion Heat of vaporization Ionization energy Melting point Oxidation state Speed of sound Thermal conductivity Thermal expansion coefficient Vapor pressure History Element discoveries Mendeleev 's predictions Naming Etymology controversies places scientists in East Asia See also IUPAC nomenclature systematic element name Trivial name Dmitri Mendeleev Book Category Chemistry Portal Periodic table ( Large cells ) 5 6 7 8 9 10 11 12 13 14 15 16 17 18 He Li Be Ne Na Mg Al Si Cl Ar Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 5 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te Xe 6 Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 7 Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og Alkali metal Alkaline earth metal Lanthanide Actinide Transition metal Post - ​ transition metal Metalloid Polyatomic nonmetal Diatomic nonmetal Noble gas Unknown chemical properties Retrieved from `` https://en.wikipedia.org/w/index.php?title=Period_3_element&oldid=810792801 '' Categories : Periods ( periodic table ) Hidden categories : Articles containing Latin - language text Articles containing Greek - language text Pages containing element color directly Talk Contents About Wikipedia Aragonés Asturianu Azərbaycanca বাংলা भोजपुरी Català Čeština Cymraeg Dansk Deutsch Español Esperanto Euskara فارسی Français Galego 한국어 Bahasa Indonesia Interlingua Italiano Latina Lumbaart Македонски Bahasa Melayu Nederlands 日本 語 Nordfriisk ਪੰਜਾਬੀ Polski Русский Simple English Slovenčina Српски / srpski Srpskohrvatski / српскохрватски Suomi தமிழ் ไทย Türkçe Українська Tiếng Việt West - Vlams 中文 Edit links This page was last edited on 17 November 2017, at 13 : 45. 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Question: in the third period as the atomic number increases from group 1 to group 18 the atomic radius
Answer: decreases