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"പിരീഡ് (ആവർത്തനപ്പട്ടിക)" എന്ന താളിന്റെ പതിപ്പുകൾ തമ്മിലുള്ള വ്യത്യാസം

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വരി 9:
== പിരീഡുകൾ ==
അറിയപ്പെടുന്ന 118 ഘടകങ്ങൾ ഉൾക്കൊള്ളുന്ന പീരിയോഡിക് പട്ടികയിൽ നിലവിൽ ഏഴ് പൂർണ്ണ പിരീഡുകളുണ്ട്. ഏതെങ്കിലും പുതിയ മൂലകങ്ങൾ കണ്ടെത്തിയാൽ അത് എട്ടാം പിരീഡിൽ സ്ഥാപിക്കും; [[ആവർത്തനപ്പട്ടിക (വികസിതം)|വിപുലീകൃത ആനുകാലിക പട്ടിക]] കാണുക. മൂലകങ്ങളെ അവയുടെ ബ്ലോക്ക് ചുവടെ വർ‌ണ്ണാധിഷ്ഠിതമാക്കിയിരിക്കുന്നു: എസ്-ബ്ലോക്കിന് ചുവപ്പ്, പി-ബ്ലോക്കിന് മഞ്ഞ, ഡി-ബ്ലോക്കിന് നീല, എഫ്-ബ്ലോക്കിന് പച്ച.
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=== പിരീഡ് 1 ===
===Period 1===
{{main|Period 1 element}}
{| style="text-align:center;"
!
!
!
|-
! [[Periodic table group|Group]]
!
! [[Alkali metal|1]]
| bgcolor="#ff9999" |
! [[Noble gas|18]]
| bgcolor="#ff9999" |
|-
! <small>Atomic #</small><br>Name
| bgcolor="#ff9999" |<span style="color:green;">1</span><br />[[Hydrogen|H]]
| bgcolor="#ff9999" |<span style="color:green;">2</span><br />[[Helium|He]]
|}
The first period contains fewer elements than any other, with only two, [[hydrogen]] and [[helium]]. They therefore do not follow the [[octet rule]], but rather a [[duplet rule]]. Chemically, helium behaves like a [[noble gas]], and thus is taken to be part of the [[group 18 element]]s. However, in terms of its nuclear structure it belongs to the [[s-block]], and is therefore sometimes classified as a [[group 2 element]], or simultaneously both 2 and 18. Hydrogen readily loses and gains an electron, and so behaves chemically as both a [[group 1 element|group 1]] and a [[group 17 element]].
 
*[[Hydrogen]] (H) is the most [[abundance of the chemical elements|abundant]] of the chemical elements, constituting roughly 75% of the universe's elemental mass.<ref>{{cite web | last=Palmer | first=David | date=November 13, 1997 | url= http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/971113i.html | title=Hydrogen in the Universe | publisher=NASA | access-date=2008-02-05}}</ref> Ionized hydrogen is just a [[proton]]. [[Star]]s in the [[main sequence]] are mainly composed of hydrogen in its [[plasma (physics)|plasma]] state. Elemental hydrogen is relatively rare on [[Earth]], and is industrially produced from [[hydrocarbon]]s such as [[methane]]. Hydrogen can form compounds with most elements and is present in [[water]] and most [[organic compound]]s.<ref>{{cite encyclopedia |encyclopedia=[[Encyclopædia Britannica]] |date =9 August 2019 |title=hydrogen|url = https://www.britannica.com/science/hydrogen|first = William Lee|last = Jolly}}</ref>
*[[Helium]] (He) exists only as a [[gas]] except in extreme conditions.<ref>{{cite web |access-date=2008-07-15 |url=http://www.webelements.com/helium/physics.html |title=Helium: physical properties |publisher=WebElements}}</ref> It is the second-lightest element and is the second-most abundant in the universe.<ref>{{cite web |access-date=2008-07-15 |url= http://www.webelements.com/helium/geology.html |title=Helium: geological information |publisher=WebElements}}</ref> Most helium was formed during the [[Big Bang]], but new helium is created through [[nuclear fusion]] of hydrogen in stars.<ref>{{cite web |access-date=2008-07-15 |url=https://www.newscientist.com/article/mg12517027.000-origin-of-the-chemical-elements.html |title= Origin of the chemical elements |work=New Scientist |date=1990-02-03 |author=Cox, Tony}}</ref> On [[Earth]], helium is relatively rare, only occurring as a byproduct of the natural [[radioactive decay|decay]] of some radioactive elements.<ref>{{cite news |title=Helium supply deflated: production shortages mean some industries and partygoers must squeak by. |newspaper=Houston Chronicle |date=2006-11-05}}</ref> Such 'radiogenic' helium is trapped within [[natural gas]] in concentrations of up to seven percent by volume.<ref>{{cite web |access-date=2008-07-15 |url=http://www.aapg.org/explorer/2008/02feb/helium.cfm |title=Helium a New Target in New Mexico |publisher=American Association of Petroleum Geologists |date=2008-02-02 |author=Brown, David}}</ref>
 
===Period 2===
{{main|Period 2 element}}
{| style="text-align:center;"
|-
! [[Periodic table group|Group]]
! [[Alkali metal|1]]
! [[Alkaline earth metal|2]]
! [[Boron group|13]]
! [[Carbon group|14]]
! [[Pnictogen|15]]
! [[Chalcogen|16]]
! [[Halogen|17]]
! [[Noble gas|18]]
|-
! <small>Atomic #</small><br>Name
| bgcolor="#ff9999" |3<br>[[Lithium|Li]]
| bgcolor="#ff9999" |4<br>[[Beryllium|Be]]
| bgcolor="#fdff8c" |5<br>[[Boron|B]]
| bgcolor="#fdff8c" |6<br>[[Carbon|C]]
| bgcolor="#fdff8c" |<span style="color:green;">7</span><br>[[Nitrogen|N]]
| bgcolor="#fdff8c" |<span style="color:green;">8</span><br>[[Oxygen|O]]
| bgcolor="#fdff8c" |<span style="color:green;">9</span><br>[[Fluorine|F]]
| bgcolor="#fdff8c" |<span style="color:green;">10</span><br>[[Neon|Ne]]
|}
Period 2 elements involve the [[s-block|2s]] and [[p-block|2p]] [[Atomic orbital|orbitals]]. They include the biologically most essential elements besides hydrogen: carbon, nitrogen, and oxygen.
*[[Lithium]] (Li) is the lightest metal and the least dense solid element.<ref name=weli>[http://www.webelements.com/lithium/ Lithium] at WebElements.</ref> In its non-ionized state it is one of the most reactive elements, and so is only ever found naturally in [[Chemical compound|compounds]]. It is the heaviest [[primordial element]] forged in large quantities during the [[Big Bang]].
*[[Beryllium]] (Be) has one of the highest [[melting point]]s of all the [[light metal]]s. Small amounts of beryllium were [[Big Bang nucleosynthesis|synthesised]] during the Big Bang, although most of it [[Nuclear decay|decayed]] or reacted further within stars to create larger nuclei, like carbon, nitrogen or oxygen. Beryllium is classified by the [[International Agency for Research on Cancer]] as a [[List of IARC Group 1 carcinogens|group 1 carcinogen]].<ref>{{cite web
| url = http://www.inchem.org/documents/iarc/vol58/mono58-1.html
| publisher = International Agency for Research on Cancer
| title = IARC Monograph, Volume 58
| year = 1993
| access-date = 2008-09-18}}</ref> Between 1% and 15% of people are sensitive to beryllium and may develop an inflammatory reaction in their [[respiratory system]] and [[skin]], called chronic beryllium disease.<ref>[https://web.archive.org/web/20010331191955/http://www.chronicberylliumdisease.com/medical/med_bediseases.htm#cbd Information] about chronic beryllium disease.</ref>
*[[Boron]] (B) does not occur naturally as a free element, but in compounds such as [[borate]]s. It is an essential plant [[micronutrient]], required for cell wall strength and development, cell division, seed and fruit development, sugar transport and hormone development,<ref>{{cite web| title =Functions of Boron in Plant Nutrition|website = www.borax.com/agriculture | url = http://www.borax.com/agriculture/files/an203.pdf | format =PDF| publisher =U.S. Borax Inc.| url-status= dead| archive-url =https://web.archive.org/web/20090320175602/http://www.borax.com/agriculture/files/an203.pdf| archive-date =2009-03-20 }}</ref><ref>{{cite journal
| title = Functions of Boron in Plant Nutrition
| first = Dale G.
| last = Blevins
|author2=Lukaszewski, Krystyna M.
| journal = Annual Review of Plant Physiology and Plant Molecular Biology
| volume = 49
| pages = 481–500
| year = 1998
| doi = 10.1146/annurev.arplant.49.1.481
| pmid = 15012243 }}</ref> though high levels are toxic.
*[[Carbon]] (C) is the fourth-most abundant element in the universe by mass after [[hydrogen]], [[helium]] and oxygen<ref>[http://plymouthlibrary.org/faqelements.htm Ten most abundant elements in the universe, taken from ''The Top 10 of Everything'', 2006, Russell Ash, page 10. Retrieved October 15, 2008.] {{webarchive|url=https://web.archive.org/web/20100210170504/http://plymouthlibrary.org/faqelements.htm |date=February 10, 2010 }}</ref> and is the [[Composition of the human body|second-most abundant element in the human body]] by mass after oxygen,<ref>{{cite book
| last = Chang
| first = Raymond
| title = Chemistry, Ninth Edition
| publisher = McGraw-Hill
| year = 2007
| pages = 52
| isbn = 0-07-110595-6 }}</ref> the third-most abundant by number of atoms.<ref name="Freitas">{{cite book |first=Robert A. |last=Freitas Jr. |title=Nanomedicine |url=http://www.foresight.org/Nanomedicine/Ch03_1.html |publisher=Landes Bioscience |year=1999 |page=Tables 3-1 & 3-2 |isbn=1-57059-680-8 |no-pp=true }}</ref> There are an almost infinite number of compounds that contain carbon due to carbon's ability to form long stable chains of C—C bonds.<ref name="hydrocarbon"/><ref name=acell>{{cite book |last = Alberts |first = Bruce|author2=Alexander Johnson |author3=Julian Lewis |author4=Martin Raff |author5=Keith Roberts |author6=Peter Walter |title = Molecular Biology of the Cell |publisher = Garland Science |url = https://www.ncbi.nlm.nih.gov/books/bv.fcgi?highlight=carbon&rid=mboc4.section.165}}</ref> All [[organic compound]]s, those essential for life, contain at least one atom of carbon;<ref name="hydrocarbon">{{cite web| title = Structure and Nomenclature of Hydrocarbons | publisher = Purdue University| url = http://chemed.chem.purdue.edu/genchem/topicreview/bp/1organic/organic.html| access-date = 2008-03-23}}</ref><ref name=acell/> combined with hydrogen, oxygen, nitrogen, sulfur, and phosphorus, carbon is the basis of every important biological compound.<ref name=acell/>
*[[Nitrogen]] (N) is found mainly as mostly [[Inert gas|inert]] [[diatomic]] gas, N<sub>2</sub>, which makes up 78% of the Earth's atmosphere by volume. It is an essential component of [[protein]]s and therefore of life.
*[[Oxygen]] (O) comprising 21% of the atmosphere by volume and is required for [[Respiration (physiology)|respiration]] by all (or nearly all) animals, as well as being the principal component of [[water]]. Oxygen is the third-most abundant element in the universe, and oxygen compounds dominate the Earth's crust.
*[[Fluorine]] (F) is the most reactive element in its non-ionized state, and so is never found that way in nature.
*[[Neon]] (Ne) is a [[noble gas]] used in [[neon lighting]].
 
===Period 3===
{{main|Period 3 element}}
{| style="text-align:center;"
|-
! [[Periodic table group|Group]]
! [[Alkali metal|1]]
! [[Alkaline earth metal|2]]
! [[Boron group|13]]
! [[Carbon group|14]]
! [[Pnictogen|15]]
! [[Chalcogen|16]]
! [[Halogen|17]]
! [[Noble gas|18]]
|-
! <small>Atomic #</small><br>Name
| bgcolor="#ff9999" |11<br>[[Sodium|Na]]
| bgcolor="#ff9999" |12<br>[[Magnesium|Mg]]
| bgcolor="#fdff8c" |13<br>[[Aluminium|Al]]
| bgcolor="#fdff8c" |14<br>[[Silicon|Si]]
| bgcolor="#fdff8c" |15<br>[[Phosphorus|P]]
| bgcolor="#fdff8c" |16<br>[[Sulfur|S]]
| bgcolor="#fdff8c" |<span style="color:green;">17</span><br>[[Chlorine|Cl]]
| bgcolor="#fdff8c" |<span style="color:green;">18</span><br>[[Argon|Ar]]
|}
 
All period three elements occur in nature and have at least one [[stable nuclide|stable isotope]]. All but the noble gas [[argon]] are essential to basic geology and biology.
*[[Sodium]] (Na) is an [[alkali metal]]. It is present in Earth's oceans in large quantities in the form of [[sodium chloride]] (table salt).
*[[Magnesium]] (Mg) is an [[alkaline earth metal]]. Magnesium [[ion]]s are found in [[chlorophyll]].
*[[Aluminium]] (Al) is a [[post-transition metal]]. It is the most abundant metal in the Earth's [[crust (geology)|crust]].
*[[Silicon]] (Si) is a [[metalloid]]. It is a [[semiconductor]], making it the principal component in many [[integrated circuits]]. [[Silicon dioxide]] is the principal constituent of [[sand]]. As Carbon is to [[Biology]], Silicon is to [[Geology]].
*[[Phosphorus]] (P) is a [[nonmetal]] essential to [[DNA]]. It is highly [[reactivity (chemistry)|reactive]], and as such is never found in nature as a free element.
*[[Sulfur]] (S) is a [[nonmetal]]. It is found in two [[amino acid]]s: [[cysteine]] and [[methionine]].
*[[Chlorine]] (Cl) is a [[halogen]]. It is used as a disinfectant, especially in [[swimming pool]]s.
*[[Argon]] (Ar) is a [[noble gas]], making it almost entirely nonreactive. [[Incandescent lamp]]s are often filled with noble gases such as argon in order to preserve the filaments at high temperatures.
 
===Period 4===
{{main|Period 4 element}}
{| style="text-align:center;"
|-
! [[Periodic table group|Group]]
! [[Alkali metal|1]]
! [[Alkaline earth metal|2]]
! [[Group 3 element|3]]
! [[Group 4 element|4]]
! [[Group 5 element|5]]
! [[Group 6 element|6]]
! [[Group 7 element|7]]
! [[Group 8 element|8]]
! [[Group 9 element|9]]
! [[Group 10 element|10]]
! [[Group 11 element|11]]
! [[Group 12 element|12]]
! [[Boron group|13]]
! [[Carbon group|14]]
! [[Pnictogen|15]]
! [[Chalcogen|16]]
! [[Halogen|17]]
! [[Noble gas|18]]
|-
! <small>Atomic #</small><br>Name
| bgcolor="#ff9999" |19<br>[[Potassium|K]]
| bgcolor="#ff9999" |20<br>[[calcium|Ca]]
| bgcolor="#99ccff" |21<br>[[scandium|Sc]]
| bgcolor="#99ccff" |22<br>[[titanium|Ti]]
| bgcolor="#99ccff" |23<br>[[Vanadium|V]]
| bgcolor="#99ccff" |24<br>[[chromium|Cr]]
| bgcolor="#99ccff" |25<br>[[manganese|Mn]]
| bgcolor="#99ccff" |26<br>[[iron|Fe]]
| bgcolor="#99ccff" |27<br>[[cobalt|Co]]
| bgcolor="#99ccff" |28<br>[[nickel|Ni]]
| bgcolor="#99ccff" |29<br>[[copper|Cu]]
| bgcolor="#99ccff" |30<br>[[Zinc|Zn]]
| bgcolor="#fdff8c" |31<br>[[gallium|Ga]]
| bgcolor="#fdff8c" |32<br>[[germanium|Ge]]
| bgcolor="#fdff8c" |33<br>[[arsenic|As]]
| bgcolor="#fdff8c" |34<br>[[selenium|Se]]
| bgcolor="#fdff8c" |<span style="color:blue;">35</span><br>[[bromine|Br]]
| bgcolor="#fdff8c" |<span style="color:green;">36</span><br>[[krypton|Kr]]
|}
 
[[File:Coloured-transition-metal-solutions.jpg|thumb|right|400px|From left to right, aqueous solutions of: [[cobalt(II) nitrate|Co(NO<sub>3</sub>)<sub>2</sub>]] (red); [[potassium dichromate|K<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub>]] (orange); [[potassium chromate|K<sub>2</sub>CrO<sub>4</sub>]] (yellow); [[nickel(II) chloride|NiCl<sub>2</sub>]] (green); [[copper(II) sulfate|CuSO<sub>4</sub>]] (blue); [[potassium permanganate|KMnO<sub>4</sub>]] (purple).]]
Period 4 includes the biologically essential elements [[potassium]] and [[calcium]], and is the first period in the [[d-block]] with the lighter [[transition metals]]. These include [[iron]], the heaviest element forged in [[main-sequence star]]s and a principal component of the Earth, as well as other important metals such as [[cobalt]], [[nickel]], and [[copper]]. Almost all have biological roles.
 
Completing the fourth period are the six p-block elements: [[gallium]], [[germanium]], [[arsenic]], [[selenium]], [[bromine]], and [[krypton]].
 
===Period 5===
{{main|Period 5 element}}
{| style="text-align:center;"
|-
! [[Periodic table group|Group]]
! [[Alkali metal|1]]
! [[Alkaline earth metal|2]]
! [[Group 3 element|3]]
! [[Group 4 element|4]]
! [[Group 5 element|5]]
! [[Group 6 element|6]]
! [[Group 7 element|7]]
! [[Group 8 element|8]]
! [[Group 9 element|9]]
! [[Group 10 element|10]]
! [[Group 11 element|11]]
! [[Group 12 element|12]]
! [[Boron group|13]]
! [[Carbon group|14]]
! [[Pnictogen|15]]
! [[Chalcogen|16]]
! [[Halogen|17]]
! [[Noble gas|18]]
|-
! <small>Atomic #</small><br>Name
| bgcolor="#ff9999" |37<br>[[rubidium|Rb]]
| bgcolor="#ff9999" |38<br>[[strontium|Sr]]
| bgcolor="#99ccff" |39<br>[[yttrium|Y]]
| bgcolor="#99ccff" |40<br>[[zirconium|Zr]]
| bgcolor="#99ccff" |41<br>[[niobium|Nb]]
| bgcolor="#99ccff" |42<br>[[molybdenum|Mo]]
| bgcolor="#99ccff" |43<br>[[technetium|Tc]]
| bgcolor="#99ccff" |44<br>[[ruthenium|Ru]]
| bgcolor="#99ccff" |45<br>[[rhodium|Rh]]
| bgcolor="#99ccff" |46<br>[[palladium|Pd]]
| bgcolor="#99ccff" |47<br>[[silver|Ag]]
| bgcolor="#99ccff" |48<br>[[cadmium|Cd]]
| bgcolor="#fdff8c" |49<br>[[indium|In]]
| bgcolor="#fdff8c" |50<br>[[tin|Sn]]
| bgcolor="#fdff8c" |51<br>[[antimony|Sb]]
| bgcolor="#fdff8c" |52<br>[[tellurium|Te]]
| bgcolor="#fdff8c" |53<br>[[iodine|I]]
| bgcolor="#fdff8c" |<span style="color:green;">54</span><br>[[xenon|Xe]]
|}
 
Period 5 has the same number of elements as period 4 and follows the same general structure but with one more post transition metal and one fewer nonmetal. Of the three heaviest elements with biological roles, two ([[molybdenum]] and [[iodine]]) are in this period; [[tungsten]], in period 6, is heavier, along with several of the early [[lanthanide]]s. Period 5 also includes [[technetium]], the lightest exclusively [[radioactive decay|radioactive]] element.
 
===Period 6===
{{main|Period 6 element}}
{| style="text-align:center;"
|-
! [[Periodic table group|Group]]
! [[Alkali metal|1]]
! [[Alkaline earth metal|2]]
! colspan="14" align="center" | &nbsp;
! [[Group 3 element|3]]
! [[Group 4 element|4]]
! [[Group 5 element|5]]
! [[Group 6 element|6]]
! [[Group 7 element|7]]
! [[Group 8 element|8]]
! [[Group 9 element|9]]
! [[Group 10 element|10]]
! [[Group 11 element|11]]
! [[Group 12 element|12]]
! [[Boron group|13]]
! [[Carbon group|14]]
! [[Pnictogen|15]]
! [[Chalcogen|16]]
! [[Halogen|17]]
! [[Noble gas|18]]
|-
! <small>Atomic #</small><br>Name
| bgcolor="#ff9999" |55<br>[[Caesium|Cs]]
| bgcolor="#ff9999" |56<br>[[Barium|Ba]]
| bgcolor="#9bff99" |57<br>[[Lanthanum|La]]
| bgcolor="#9bff99" |58<br>[[Cerium|Ce]]
| bgcolor="#9bff99" |59<br>[[Praseodymium|Pr]]
| bgcolor="#9bff99" |60<br>[[Neodymium|Nd]]
| bgcolor="#9bff99" |61<br>[[Promethium|Pm]]
| bgcolor="#9bff99" |62<br>[[Samarium|Sm]]
| bgcolor="#9bff99" |63<br>[[Europium|Eu]]
| bgcolor="#9bff99" |64<br>[[Gadolinium|Gd]]
| bgcolor="#9bff99" |65<br>[[Terbium|Tb]]
| bgcolor="#9bff99" |66<br>[[Dysprosium|Dy]]
| bgcolor="#9bff99" |67<br>[[Holmium|Ho]]
| bgcolor="#9bff99" |68<br>[[Erbium|Er]]
| bgcolor="#9bff99" |69<br>[[Thulium|Tm]]
| bgcolor="#9bff99" |70<br>[[Ytterbium|Yb]]
| bgcolor="#99ccff" |71<br>[[Lutetium|Lu]]
| bgcolor="#99ccff" |72<br>[[Hafnium|Hf]]
| bgcolor="#99ccff" |73<br>[[Tantalum|Ta]]
| bgcolor="#99ccff" |74<br>[[Tungsten|W]]
| bgcolor="#99ccff" |75<br>[[Rhenium|Re]]
| bgcolor="#99ccff" |76<br>[[Osmium|Os]]
| bgcolor="#99ccff" |77<br>[[Iridium|Ir]]
| bgcolor="#99ccff" |78<br>[[Platinum|Pt]]
| bgcolor="#99ccff" |79<br>[[Gold|Au]]
| bgcolor="#99ccff" |<span style="color:blue;">80</span><br>[[Mercury (element)|Hg]]
| bgcolor="#fdff8c" |81<br>[[Thallium|Tl]]
| bgcolor="#fdff8c" |82<br>[[Lead|Pb]]
| bgcolor="#fdff8c" |83<br>[[Bismuth|Bi]]
| bgcolor="#fdff8c" |84<br>[[Polonium|Po]]
| bgcolor="#fdff8c" |85<br>[[Astatine|At]]
| bgcolor="#fdff8c" |<span style="color:green;">86</span><br>[[Radon|Rn]]
|}
Period 6 is the first period to include the [[f-block]], with the [[lanthanide]]s (also known as the [[rare earth element]]s), and includes the heaviest stable elements. Many of these [[heavy metals]] are toxic and some are radioactive, but [[platinum]] and [[gold]] are largely inert.
 
===Period 7===
{{main|Period 7 element}}
{| style="text-align:center;"
|-
! [[Periodic table group|Group]]
! [[Alkali metal|1]]
! [[Alkaline earth metal|2]]
! colspan="14" align="center" | &nbsp;
! [[Group 3 element|3]]
! [[Group 4 element|4]]
! [[Group 5 element|5]]
! [[Group 6 element|6]]
! [[Group 7 element|7]]
! [[Group 8 element|8]]
! [[Group 9 element|9]]
! [[Group 10 element|10]]
! [[Group 11 element|11]]
! [[Group 12 element|12]]
! [[Boron group|13]]
! [[Carbon group|14]]
! [[Pnictogen|15]]
! [[Chalcogen|16]]
! [[Halogen|17]]
! [[Noble gas|18]]
|-
! <small>Atomic #</small><br>Name
| bgcolor="#ff9999" |87<br>&nbsp;[[Francium|Fr]]&nbsp;
| bgcolor="#ff9999" |88<br>[[Radium|Ra]]
| bgcolor="#9bff99" |89<br>[[Actinium|Ac]]
| bgcolor="#9bff99" |90<br>[[Thorium|Th]]
| bgcolor="#9bff99" |91<br>[[Protactinium|Pa]]
| bgcolor="#9bff99" |92<br>[[Uranium|U]]
| bgcolor="#9bff99" |93<br>[[Neptunium|Np]]
| bgcolor="#9bff99" |94<br>[[Plutonium|Pu]]
| bgcolor="#9bff99" |95<br>[[Americium|Am]]
| bgcolor="#9bff99" |96<br>[[Curium|Cm]]
| bgcolor="#9bff99" |97<br>[[Berkelium|Bk]]
| bgcolor="#9bff99" |98<br>[[Californium|Cf]]
| bgcolor="#9bff99" |99<br>[[Einsteinium|Es]]
| bgcolor="#9bff99" |<span style="font-size:66%;">100</span><br>[[Fermium|Fm]]
| bgcolor="#9bff99" |<span style="font-size:66%;">101</span><br>[[Mendelevium|Md]]
| bgcolor="#9bff99" |<span style="font-size:66%;">102</span><br>[[Nobelium|No]]
| bgcolor="#99ccff" |<span style="font-size:66%;">103</span><br>[[Lawrencium|Lr]]
| bgcolor="#99ccff" |<span style="color:gray; font-size:66%;">104</span><br>[[Rutherfordium|Rf]]
| bgcolor="#99ccff" |<span style="color:gray; font-size:66%;">105</span><br>[[Dubnium|Db]]
| bgcolor="#99ccff" |<span style="color:gray; font-size:66%;">106</span><br>[[Seaborgium|Sg]]
| bgcolor="#99ccff" |<span style="color:gray; font-size:66%;">107</span><br>[[Bohrium|Bh]]
| bgcolor="#99ccff" |<span style="color:gray; font-size:66%;">108</span><br>[[Hassium|Hs]]
| bgcolor="#99ccff" |<span style="color:gray; font-size:66%;">109</span><br>[[Meitnerium|Mt]]
| bgcolor="#99ccff" |<span style="color:gray; font-size:66%;">110</span><br>[[Darmstadtium|Ds]]
| bgcolor="#99ccff" |<span style="color:gray; font-size:66%;">111</span><br>[[Roentgenium|Rg]]
| bgcolor="#99ccff" |<span style="color:gray; font-size:66%;">112</span><br>[[Copernicium|Cn]]
| bgcolor="#fdff8c" |<span style="color:gray; font-size:66%;">113</span><br>[[Nihonium|Nh]]
| bgcolor="#fdff8c" |<span style="color:gray; font-size:66%;">114</span><br>[[Flerovium|Fl]]
| bgcolor="#fdff8c" |<span style="color:gray; font-size:66%;">115</span><br>[[Moscovium|Mc]]
| bgcolor="#fdff8c" |<span style="color:gray; font-size:66%;">116</span><br>[[Livermorium|Lv]]
| bgcolor="#fdff8c" |<span style="color:gray; font-size:66%;">117</span><br>[[Tennessine|Ts]]
| bgcolor="#fdff8c" |<span style="color:gray; font-size:66%;">118</span><br>[[Oganesson|Og]]
|}
All elements of period 7 are [[radioactive]]. This period contains the heaviest element which occurs naturally on Earth, [[plutonium]]. All of the subsequent elements in the period have been synthesized artificially. Whilst five of these (from [[americium]] to [[einsteinium]]) are now available in macroscopic quantities, most are extremely rare, having only been prepared in microgram amounts or less. Some of the later elements have only ever been identified in laboratories in quantities of a few atoms at a time.
 
Although the rarity of many of these elements means that experimental results are not very extensive, periodic and group trends in behaviour appear to be less well defined for period 7 than for other periods. Whilst [[francium]] and [[radium]] do show typical properties of groups 1 and 2, respectively, the [[actinides]] display a much greater variety of behaviour and oxidation states than the [[lanthanides]]. These peculiarities of period 7 may be due to a variety of factors, including a large degree of [[spin-orbit coupling]] and relativistic effects, ultimately caused by the very high positive electrical charge from their massive [[atomic nuclei]].
 
===Period 8===
{{main|Extended periodic table}}
No element of the eighth period has yet been synthesized. A [[g-block]] is predicted. It is not clear if all elements predicted for the eighth period are in fact physically possible. There may therefore be no eighth period.
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