Block periodic table (2025)

• s-block
• p-block
• d-block
• f-block
• g-block(hypothetical)

The blocknames (s, p, d, f and g) are derived from thespectroscopicnotationfor the associatedatomic orbitals:sharp,principal,diffuseandfundamental, and then g which follows f in the alphabet.

The followingis the order for filling the "subshell" orbitals, according totheAufbau principle, which also gives thelinear order of the "blocks" (as atomic number increases) in theperiodic table:

1s, 2s,2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, ...

For discussionof the nature of why the energies of the blocks naturally appear in this orderin complex atoms, seeatomic orbitalandelectron configuration.

The"periodic" nature of the filling of orbitals, as well as emergence ofthes,p,dandf"blocks"is more obvious, if this order of filling is given in matrix form, withincreasing principal quantum numbers starting the new rows("periods") in the matrix. Then, each subshell (composed of the firsttwo quantum numbers) is repeated as many times as required for each pair ofelectrons it may contain. The result is a compressed periodic table, with eachentry representing two successive elements:

1s2s 2p 2p 2p3s 3p 3p 3p4s 3d 3d 3d 3d 3d 4p 4p 4p5s 4d 4d 4d 4d 4d 5p 5p 5p6s 4f 4f 4f 4f 4f 4f 4f 5d 5d 5d 5d 5d 6p 6p 6p7s 5f 5f 5f 5f 5f 5f 5f 6d 6d 6d 6d 6d 7p 7p 7p

The s-block ison the left side of the periodic table that includes elements from the firsttwo columns, the alkali metals (group 1) and alkaline earth metals (group 2),plus helium. Helium is a controversial element for the scientists as it can beplaced in s block as well as p block too but most of the scientists consider itto be rest at the top of group 18 i.e. above neon(atomic number 10) as it hasmany properties similar to the group 18 elements.

Most s-blockelements are highly reactive metals due to the ease with which their outers-orbital electrons interact to form compounds. The first period elements inthis block, however, are nonmetals. Hydrogen is highly chemically reactive,like the other s-block elements, but helium is a virtually unreactive noblegas.

S-blockelements are unified by the fact that their valence electrons (outermostelectrons) are in the s orbital. The s-orbital is a single spherical cloudwhich can contain only one pair of electrons; hence, the s-block consists ofonly two columns in the periodic table. Elements in column 1, with a singles-orbital valence electron, are the most reactive of the block. Elements in thesecond column have two s-orbital valence electrons, and, except for helium, areonly slightly less reactive.

p-block

The p-block ison the right side of the periodic table and includes elements from the sixcolumns beginning with column 13 and ending with column 18. Helium, though beingin the top of group 18, is not included in the p-block.

The p-block ishome to the biggest variety of elements and is the only block that contains allthree types of elements: metals, nonmetals, and metalloids. Generally, thep-block elements are best described in terms of element type or group.

P-blockelements are unified by the fact that their valence electrons (outermostelectrons) are in the p orbital. The p orbital consists of six lobed shapescoming off a central point at evenly spaced angles. The p orbital can hold amaximum of six electrons, hence there are six columns in the p-block. Elementsin column 13, the first column of the p-block, have one p-orbital electron.Elements in column 14, the second column of the p-block, have two p-orbitalelectrons. The trend continues this way until we reach column 18, which has sixp-orbital electrons.

Metals

P-block metalshave classic metal characteristics: they are shiny, they are good conductors ofheat and electricity, and they lose electrons easily. Generally, these metalshave high melting points and readily react with nonmetals to form ioniccompounds. Ionic compounds form when a positive metal ion bonds with a negativenonmetal ion.

Of the p-blockmetals, several have fascinating properties. Gallium, in the 3rd row of column13, is a metal that can melt in the palm of a hand. Tin, in the fourth row ofcolumn 14, is an abundant, flexible, and extremely useful metal. It is animportant component of many metal alloys like bronze, solder, and pewter.

Sitting rightbeneath tin is lead, a toxic metal. Ancient people used lead for a variety ofthings, from food sweeteners to pottery glazes to eating utensils. It has beensuspected that lead poisoning is related to the fall of Roman civilization,[3]but further research has shown this to be unlikely.[4][5] For a long time, leadwas used in the manufacturing of paints. It was only within the last centurythat lead paint use has been restricted due to its toxic nature.

Metalloids

Metalloids haveproperties of both metals and nonmetals, but the term 'metalloid' lacks astrict definition. All of the elements that are commonly recognized asmetalloids are in the p-block: boron, silicon, germanium, arsenic, antimony,and tellurium. Metalloids tend to have lower electrical conductivity thanmetals, yet often higher than nonmetals. They tend to form chemical bondssimilarly to nonmetals, but may dissolve in metallic alloys without covalent orionic bonding. Metalloid additives can improve properties of metallic alloys,sometimes paradoxically to their own apparent properties. Some may give abetter electrical conductivity, higher corrosion resistance, ductility, orfluidity in molten state, etc. to the alloy.

Boron has manycarbon-like properties, but is very rare. It has many uses, for example a Ptype semiconductor dopant.

Silicon isperhaps the most famous metalloid. It is the second most abundant element inEarth's crust and one of the main ingredients in glass. It is used to makemicrochips for computers and other electronic devices. It is also used incertain metallic alloys, e.g. to improve casting properties of alumimium. Sovaluable is silicon to the technology industry that Silicon Valley in Californiais named after it.

Germanium hasproperties very similar to silicon, yet this element is much more rare. It wasonce used for its semiconductor properties pretty much as silicon is now, andit has some superior properties at that, but is now a rare material in theindustry.

Arsenic is atoxic metalloid that has been used throughout history as an additive to metalalloys, paints, and even makeup.

Antimony isused as a constituent in casting alloys such as printing metal.

Not alwaysconsidered as metalloids:

Carbon, in thesame column with silicon and germanium, electrically fairly conductive unlikemost other nonmetals, and to an extent preferred as a trace constituent incertain metallic alloys such as steel

Phosphorus hasmetallurgical uses among others, e.g. a constituent of some copper alloys

Selenium, onceused as a semiconductor material, and also used to improve properties ofmetallic alloys

Aluminium isgenerally considered a metal, but it has some metalloid/non-metal propertiessuch as negative oxidation states

Noblegases

Previouslycalled inert gases, their name was changed as there are a few other gases thatare inert but not noble gases, such as nitrogen. The noble gases are located inthe far right column of the periodic table, also known as Group Zero or GroupEighteen. Noble gases are also called as aerogens but this nomenclature of thegroup is not officially accepted by the IUPAC.

All of thenoble gases have full outer shells with eight electrons. However, at the top ofthe noble gases is helium, with a shell that is full with only two electrons.The fact that their outer shells are full means they rarely react with otherelements, which led to their original title of "inert."

Because oftheir chemical properties, these gases are also used in the laboratory to helpstabilize reactions that would usually proceed too quickly. As the atomicnumbers increase, the elements become rarer. They are not just rare in nature,but rare as useful elements, too.

Helium is bestknown for its low density, used to safely produce buoyancy for zeppelins andballoons

Neon isnotorious as the red to yellow glow medium of old low power signal lamps andsigns

Argon is usedas a protective gas in MIG and TIG welding

Xenon is usedas a plasma medium in high intensity arc lamps with tungsten electrodes.Automotive xenon lights, however, are mostly mercury vapor bulbs with lowpressure xenon to help striking the arc and producing light instantly.

Krypton hasmany uses like arc flash medium. Krypton filled incandescent bulbs were oncethe most efficient variety, before being replaced by halogen technology.

Radon isradioactive, and one of the densest elements to remain in gas state at roomtemperature

Halogens

The secondcolumn from the right side of the periodic table, group 17, is the halogenfamily of elements. These elements are all just one electron shy of having fullshells. Because they are so close to being full, they have the trait ofcombining with many different elements and are very reactive. They are oftenfound bonding with metals and elements from Group One, as these elements ineach have one electron.

Not allhalogens react with the same intensity. Fluorine is the most reactive andcombines with most elements from around the periodic table. As with othercolumns, reactivity decreases as the atomic number increases.

When a halogencombines with another element, the resulting compound is called a halide. Oneof the best examples of a halide is sodium chloride (NaCl).

d-block

The d-block ison the middle of the periodic table and includes elements from columns 3through 12. These elements are also known as the transition metals because theyshow a transitivity in their properties i.e. they show a trend in theirproperties

The d-blockelements are all metals which exhibit two or more ways of forming chemicalbond. Because there is a relatively small difference in the energy of thedifferent d-orbital electrons, the number of electrons participating inchemical bonding can vary. This results in the same element exhibiting two ormore oxidation states, which determines the type and number of its nearestneighbors in chemical compounds.

D-blockelements are unified by having in their outermost electrons one or mored-orbital electrons but no p-orbital electrons. The d-orbitals can contain upto five pairs of electrons; hence, the block includes ten columns in theperiodic table.

f-block

The f-block isin the center-left of a 32-column periodic table but in the footnoted appendageof 18-column tables. These elements are not generally considered as part of anygroup. They are often called inner transition metals because they provide atransition between the s-block and d-block in the 6th and 7th row (period), inthe same way that the d-block transition metals provide a transitional bridgebetween the s-block and p-block in the 4th and 5th rows.

The knownf-block elements come in two series, the lanthanides of period 6 and theradioactive actinides of period 7. All are metals. Because the f-orbitalelectrons are less active in determining the chemistry of these elements, theirchemical properties are mostly determined by outer s-orbital electrons.Consequently, there is much less chemical variability within the f-block thanwithin the s-, p-, or d-blocks.

F-blockelements are unified by having one or more of their outermost electrons in thef-orbital but none in the d-orbital or p-orbital. The f-orbitals can contain upto seven pairs of electrons; hence, the block includes fourteen columns in theperiodic table.

g-block

Source: Wikipedia