<< Chapter < Page Chapter >> Page >

White phosphorus was originally made commercially for the match industry in the 19 th century, by distilling off phosphorus vapor from precipitated phosphates, mixed with ground coal or charcoal, [link] . The precipitated phosphates were made from ground-up bones that had been de-greased and treated with strong acids. This process is, however, obsolete due to the submerged-arc furnace for phosphorus production was introduced to reduce phosphate rock. Calcium phosphate (phosphate rock) is heated to 1200 - 1500 °C with SiO 2 and coke (impure carbon) to produce vaporized tetraphosphorus, P 4 .

Physical properties

The physical properties of the Group 15 elements ( [link] ) encompasses a gas (N 2 ), a non-metallic solid (P 4 ), metalloids (As and Sb), and a metal (Bi).

Selected physical properties of the Group 15 elements.
Element Mp (°C) Bp (°C) Density (g/cm 3 )
N -210.00 -195.79 1.251 g/L (0 °C @ 101.325 kPa)
P 44.2 (white), 610 (black) 280.5 (white), 416 - 590 (sub., red), 620 (sub, violet) 1.823 (white), 2.2 - 2.34 (red), 2.36 (violet), 2.69 (black)
As 817 615 (sub.) 5.727
Sb 630.63 1587 6.697 (solid), 6.53 (liquid)
Bi 271.5 1564 9.78 (solid), 10.05 (liquid)

Vapor phase

Nitrogen forms a dimer in the vapor phase with a triple bond ( [link] ). In the vapor phase above 800 °C tetraphosphorus (P 4 ) is partially dissociated to P 2 .

Molecular orbital diagram for the formation of N 2 .

Solid state

Phosphorus forms a number of allotropes with very different properties ( [link] ). Red phosphorus is an intermediate phase between the white and violet forms. Scarlet phosphorus is obtained by allowing a solution of white phosphorus in carbon disulfide to evaporate in sunlight. Black phosphorus is formed by heating white phosphorus under high pressures ( ca . 12,000 atmospheres).

Images of (left to right) white, red, violet and black allotropes of phosphorus.

White phosphorus has two forms, low-temperature β form and high-temperature α form; both of which contain the P4 tetrahedron ( [link] ). White phosphorus is the least stable, the most reactive, most volatile, less dense, and most toxic of the allotropes.

The structure of the P 4 molecule in white phosphorus.

The structural relationship between white and red phosphorus involves breaking one of the P-P bonds in the P 4 unit and forming a bond with a neighboring tetrahedron to give a chain structure ( [link] ). Red phosphorus is formed by heating white phosphorus to 250 °C or by exposing white phosphorus to sunlight. Actually red phosphorus is not a single allotrope, but rather an intermediate phase between the white and violet phosphorus, and most of its properties have a range of values ( [link] ).

Crystal unit cell of red phosphorus.

Violet phosphorus ( [link] ) is the thermodynamic stable form of phosphorus that is produced by heating red phosphorus above 550 °C. Due to the synthesis being developed by Johann Hittorf ( [link] ) it is sometimes known as Hittorf's phosphorus .

Structure of violet (Hittorf’s) phosphorus.
German physicist Johann Wilhelm Hittorf (1824 - 1914).

Black phosphorus is the least reactive allotrope and the thermodynamic stable form below 550 °C. It is also known as β-metallic phosphorus and has a structure somewhat resembling that of graphite ( [link] ).

Crystal structure of black phosphorus.

In a similar manner to phosphorus, arsenic has several allotropes some of which a structurally related to those of phosphorus. Grey arsenic has a structure similar to black phosphorus ( [link] ). Yellow arsenic (As 4 ) is soft and waxy with a structure similar to too P 4 ( [link] ). Finally, black arsenic is similar in structure to red phosphorus ( [link] ). Antimony and bismuth are both traditional metals and have trigonal hexagonal structures ( a = 4.299, c = 11.25 Å, and a = 4.537, c = 11.838 Å, respectively).


  • V. Biringuccio, The Pirotechnia of Vannoccio Biringuccio: The Classic Sixteenth-Century Treatise on Metals and Metallurgy , Dover Publications (1990).

Questions & Answers

is economics important in programming world?
Abdul Reply
What is oppunity cost
Kudzanayi Reply
it refers wants that are left unsatisfied in Oder satisfy another more pressing need
Thank bro
is the second altenative to foregone
How does monopoly and imperfect competion;public goods externalities ass symmetric information, ommon property ressourses; income distribution Merit goods and Macroeconomic growth and stability causes market failure?
it is where by a labour moves from one place to another
Amoako Reply
what is mobility of labour
George Reply
who best defined economics
paul Reply
what are the importance of economics
Adwoa Reply
trade should be best
help to know how our government operates in which system
1. To solve economic problems. 2. To predict economic event. 3. It also offer intellectual training to students.
How price elasticity can affect the markets of certain goods
Rhoda Reply
Heyy thanks for the teaching
Easter Reply
what is labour
Arthur Reply
Mental and physical ability of human being is considered as labour.
and usually provided by human
is all human effort both physical and mental abilities to work
why is it that most countries in Africa abuse available resources
Okeoghene Reply
What is economics
Bright Reply
economics is a science which studies human behaviour as a relationship between ends, scarce means which have alternative uses.
Why is scarcity a mind problem in economics
Alima Reply
because of the problem of allocation of resources
unequalled distribution of resources
scarcity is a mind problem due to circumstances like when a particular product is demand in a high rate at the market.
scarcity defines limited in supply relative to the demand them. so scarcity is a mind problem in economics because wants are unlimited while resources are also limited.
it is a mind problem because it's one of the fundamental issue address by economics human wants are unlimited and resources available are limited this makes the study of economics essential
its a fundamental issue
it's not a mind problem, I think it's a economic problem, how to allocate scarce resources to satisfy need and want of society
Identify the different sectors in the economy
Moses Reply
what is economics
economic is study of human behaviour according to how they satisfie their numerous want
Economics is a science which studies human behaviour as a relationship between ends and scares resources.
economic is study of human behaviour according to how they satisfie their numerous want
what is the law of demand
Adugbire Reply
the lower the price the higher the quantity demanded vice versa is true
yes ooh
what are relationship between unemployment and economic growth
Weness Reply
no relationship
When there is economic growth, there is increased opportunity in employment. When there is no economic growth mean there is recession causing a decline or downsizing in employment opportunities.
unemployment or employment determined by the level of economic growth
waht is hydrating power of lithium carbonates
Mahar Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Chemistry of the main group elements. OpenStax CNX. Aug 20, 2010 Download for free at http://cnx.org/content/col11124/1.25
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Chemistry of the main group elements' conversation and receive update notifications?