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The name phosphorus comes from the Greek words meaning light bringing. When phosphorus was first isolated, scientists noted that it glowed in the dark and burned when exposed to air. Phosphorus is the only member of its group that does not occur in the uncombined state in nature; it exists in many allotropic forms. We will consider two of those forms: white phosphorus and red phosphorus.

White phosphorus is a white, waxy solid that melts at 44.2 °C and boils at 280 °C. It is insoluble in water (in which it is stored—see [link] ), is very soluble in carbon disulfide, and bursts into flame in air. As a solid, as a liquid, as a gas, and in solution, white phosphorus exists as P 4 molecules with four phosphorus atoms at the corners of a regular tetrahedron, as illustrated in [link] . Each phosphorus atom covalently bonds to the other three atoms in the molecule by single covalent bonds. White phosphorus is the most reactive allotrope and is very toxic.

Two photos and two diagrams are shown and labeled “a,” “b,” “c,” and “d.” Photo a shows a test tube that contains a solid yellow compound. Diagram b shows a four-sided pyramid shape that has an atom at each corner. Photo c shows a dark black powder in a watch glass. Diagram d shows two four-sided pyramid shapes that have an atom at each corner and are connected together by a single bond.
(a) Because white phosphorus bursts into flame in air, it is stored in water. (b) The structure of white phosphorus consists of P 4 molecules arranged in a tetrahedron. (c) Red phosphorus is much less reactive than is white phosphorus. (d) The structure of red phosphorus consists of networks of P 4 tetrahedra joined by P-P single bonds. (credit a: modification of work from http://images-of-elements.com/phosphorus.php)

Heating white phosphorus to 270–300 °C in the absence of air yields red phosphorus. Red phosphorus (shown in [link] ) is denser, has a higher melting point (~600 °C), is much less reactive, is essentially nontoxic, and is easier and safer to handle than is white phosphorus. Its structure is highly polymeric and appears to contain three-dimensional networks of P 4 tetrahedra joined by P-P single bonds. Red phosphorus is insoluble in solvents that dissolve white phosphorus. When red phosphorus is heated, P 4 molecules sublime from the solid.


The allotropy of sulfur is far greater and more complex than that of any other element. Sulfur is the brimstone referred to in the Bible and other places, and references to sulfur occur throughout recorded history—right up to the relatively recent discovery that it is a component of the atmospheres of Venus and of Io, a moon of Jupiter. The most common and most stable allotrope of sulfur is yellow, rhombic sulfur, so named because of the shape of its crystals. Rhombic sulfur is the form to which all other allotropes revert at room temperature. Crystals of rhombic sulfur melt at 113 °C. Cooling this liquid gives long needles of monoclinic sulfur. This form is stable from 96 °C to the melting point, 119 °C. At room temperature, it gradually reverts to the rhombic form.

Both rhombic sulfur and monoclinic sulfur contain S 8 molecules in which atoms form eight-membered, puckered rings that resemble crowns, as illustrated in [link] . Each sulfur atom is bonded to each of its two neighbors in the ring by covalent S-S single bonds.

Four diagrams are shown and labeled “a,” “b,” “c,” and “d.” Diagram a shows four ring structures that are each made up of eight single bonded atoms. Diagram b shows four chains of eight atoms. Diagram c shows three chains of atoms, one composed by nine atoms, one by twelve atoms and one by eleven atoms. Diagram d shows the same three chains, but this time they are much closer together and slightly intertwined.
These four sulfur allotropes show eight-membered, puckered rings. Each sulfur atom bonds to each of its two neighbors in the ring by covalent S-S single bonds. Here are (a) individual S 8 rings, (b) S 8 chains formed when the rings open, (c) longer chains formed by adding sulfur atoms to S 8 chains, and (d) part of the very long sulfur chains formed at higher temperatures.

Questions & Answers

what is measurement
Isaiah Reply
is the comparison of an unknown quantity with a fixed quantity of the same kind
How does an element differ from a compound? How are they similar?
Adeola Reply
an element is an indivisible particles that can take part in a reaction and consist of smaller or tiny particles i.e proton, neutrons and electron while a compound is when two or more element chemically combine together. They are similar when they are homogeneous compound. they take the same rxn.
How to get the Lewis formula of SeCl+3
Erica Reply
hi,I'm new here can I join the conversation
what is the structural formula for starch
EZEA Reply
Starch is a mixture (of chemicals) of amylose and amylopectin. Both are macromolecules and polymers. You can search on wikipedia.
what is the roles of filter bed
what is the roles of Alu m
what is the roles of chlorine
Roles can be classified or correlate it to different areas: For example: Chlorine can be used in reactions (in industry) to manufacture HCl, which then can be used for other things. Or in swimming pools to kill bacteria. Or as a component in compounds with pharmaceutical roles (drugs). For Al:
Its dentisty value is suitable to be used in alloys (mixture of metals) in aircraft bodies. Also, Aluminium foils, Tin cans,.. Some of them are also in Al overhead cables in streets and long roads.
what is chemistry
what is the meaning of exceedingly
Yushao Reply
it is an adverb which means extremely
what is atomic chemistry?
Gladys Reply
Lewis structure for no3
Lewis structure for no3
what is weak acid
Muhammed Reply
It is an acid which partially ionises in water.
what is incandescence
what makes it glow
why is it red, irange and yellow in color
hello am new here and I want to join you
hello i am new here please i want to join this group
Hi, I'm also new here
hello guys !!
what is pressure?
Slark Reply
The force applied to suction Area of the body
Matter composed of exceedingly small paticle called atom.
questions related to metals
Regina Reply
occurrence and preparation of the representatives metals
list the 20, periodic table and their symbols
Fathmat Reply
hydrogen:h helium;he lithium:l beryllium:be Boron:b Carbon;C Nitrogen:n Oxygen:O FLUORINE:f Neon:n Sodium:s Magnesium:mg Aluminum:a Silicon:s Phosphorus:p Sulphur:s Chlorine:c Argon;a Potassium:p Calcium:c
Hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon, sodium, magnesium, aluminium, silicon, phosphorus, sulphur, chlorine, argon, potassium, calcium
what is a solute
Ekezie Reply
Any substance that is disolved in a liqid solvent to create a solution
sorry liquid
it's a liquid substance
hello group
is the substance that dissolves in the solvent
so is HCl ionic compound
Honest Reply
No, covalent compound ➡️ molecule. As both H and Cl are non-metals and and form covalent bind by sharing valence e-. But can fully ionice in water forming H+ (a proton, a reason for acidity) and Cl- (anion =Chloride) Hydrogen Chloride is a gas at room; Hydrochloric acid = HCl (aq), dissolved in w
Form covalenr bond*
The question marks are an emoji in the first sentence is an unread emoji. HCl Covalent compund -> molecule
what is chemistry
Chukwu Reply
is the study of composition of substances and the way they behave under different conditions
how do calculate n1 though n6 any help on understanding the concept
where can I get the test bank or mcqs ? any idea ?
Sourav Reply
what are the types of intermolecular forces between organic compounds
Eke Reply
Intermolecular forces exist between molecules of different units like van der waal force, hydrogen bonds
Practice Key Terms 2

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Source:  OpenStax, Chemistry. OpenStax CNX. May 20, 2015 Download for free at http://legacy.cnx.org/content/col11760/1.9
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