Period 1 element

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A period 1 element is one of the chemical elements in the first 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 chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The first period contains fewer elements than any other row in the table, with only two: hydrogen and helium. Helium behaves as a noble gas, and is taken as the end of the row; the next period contains eight elements, as it is not until then that another element behaving as a noble gas occurs. This situation can be explained by modern theories of atomic structure.

Contents

Overview

A period 1 element is one of the chemical elements in the first row (or "period") of the periodic table of the chemical elements. This first period contains fewer elements than any other row in the table, with only hydrogen and helium. In a quantum mechanical description of atomic structure, this period corresponds to the filling of the 1s orbital. Period 1 elements do not obey the octet rule. The maximum number of electrons that both elements can accommodate is two; an element with a configuration of two elements is called a duet.

Elements

Hydrogen

Main article: Hydrogen

Hydrogen (H) is the chemical element with atomic number 1. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H2. With an atomic mass of 1.00794 amu, hydrogen is the lightest element.[1]

Hydrogen is the most abundant of the chemical elements, constituting roughly 75% of the universe's elemental mass.[2] Stars in the main sequence are mainly composed of hydrogen in its plasma state. Elemental hydrogen is relatively rare on Earth, and is industrially produced from hydrocarbons such as methane, after which most elemental hydrogen is used "captively" (meaning locally at the production site), with the largest markets almost equally divided between fossil fuel upgrading, such as hydrocracking, and ammonia production, mostly for the fertilizer market. Hydrogen may be produced from water using the process of electrolysis, but this process is significantly more expensive commercially than hydrogen production from natural gas.[3]

The most common naturally occurring isotope of hydrogen, known as protium, has a single proton and no neutrons.[4] In ionic compounds, it can take on either a positive charge, becoming a cation composed of a bare proton, or a negative charge, becoming an anion known as a hydride. Hydrogen can form compounds with most elements and is present in water and most organic compounds.[5] It plays a particularly important role in acid-base chemistry, in which many reactions involve the exchange of protons between soluble molecules.[6] As the only neutral atom for which the Schrödinger equation can be solved analytically, study of the energetics and spectrum of the hydrogen atom has played a key role in the development of quantum mechanics.[7]

The interactions of hydrogen with various metals are very important in metallurgy, as many metals can suffer hydrogen embrittlement,[8] and in developing safe ways to store it for use as a fuel.[9] Hydrogen is highly soluble in many compounds composed of rare earth metals and transition metals[10] and can be dissolved in both crystalline and amorphous metals.[11] Hydrogen solubility in metals is influenced by local distortions or impurities in the metal crystal lattice.[12]

Helium

Main article: Helium

Helium (He) is a colorless, odorless, tasteless, non-toxic, inert monatomic chemical element that heads the noble gas series in the periodic table and whose atomic number is 2.[13] Its boiling and melting points are the lowest among the elements and it exists only as a gas except in extreme conditions.[14]

Helium was discovered in 1868 by French astronomer Pierre Janssen, who first detected the substance as an unknown yellow spectral line signature in light from a solar eclipse.[15] In 1903, large reserves of helium were found in the natural gas fields of the United States, which is by far the largest supplier of the gas.[16] The substance is used in cryogenics,[17] in deep-sea breathing systems,[18] to cool superconducting magnets, in helium dating,[19] for inflating balloons,[20] for providing lift in airships,[21] and as a protective gas for industrial uses such as arc welding and growing silicon wafers.[22] Inhaling a small volume of the gas temporarily changes the timbre and quality of the human voice.[23] The behavior of liquid helium-4's two fluid phases, helium I and helium II, is important to researchers studying quantum mechanics and the phenomenon of superfluidity in particular,[24] and to those looking at the effects that temperatures near absolute zero have on matter, such as with superconductivity.[25]

Helium is the second lightest element and is the second most abundant in the observable universe.[26] Most helium was formed during the Big Bang, but new helium is being created as a result of the nuclear fusion of hydrogen in stars.[27] On Earth, helium is relatively rare and is created by the natural decay of some radioactive elements[28] because the alpha particles that are emitted consist of helium nuclei.[29] This radiogenic helium is trapped with natural gas in concentrations of up to seven percent by volume,[30] from which it is extracted commercially by a low-temperature separation process called fractional distillation.[31]

Table of elements

Chemical elements in the first period
Group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
#
Name		 1
H		 2
He
e--conf.

Notes

  1. ^ "Hydrogen – Energy". Energy Information Administration. Retrieved on 2008-07-15.
  2. ^ Palmer, David (November 13, 1997). "Hydrogen in the Universe". NASA. Retrieved on 2008-02-05.
  3. ^ Staff (2007). "Hydrogen Basics — Production". Florida Solar Energy Center. Retrieved on 2008-02-05.
  4. ^ Sullivan, Walter (1971-03-11). "Fusion Power Is Still Facing Formidable Difficulties", The New York Times. 
  5. ^ "hydrogen". Encyclopædia Britannica. (2008). 
  6. ^ "Electron-Driven Acid-Base Chemistry: Proton Transfer from Hydrogen Chloride to Ammonia" (2008-02-15). Science Magazine 319 (5865): 936–939. doi:10.1126/science.1151614. Retrieved on 2008-07-15. 
  7. ^ "Time-dependent Schrödinger equation". Encyclopædia Britannica. (2008). 
  8. ^ Rogers, H. C. (1999). "Hydrogen Embrittlement of Metals". Science 159 (3819): 1057–1064. doi:10.1126/science.159.3819.1057. PMID 17775040. 
  9. ^ Christensen, C. H.; Nørskov, J. K.; Johannessen, T. (July 9, 2005). "Making society independent of fossil fuels — Danish researchers reveal new technology", Technical University of Denmark. Retrieved on 2008-03-28. 
  10. ^ Takeshita, T.; Wallace, W.E.; Craig, R.S. (1974). "Hydrogen solubility in 1:5 compounds between yttrium or thorium and nickel or cobalt". Inorganic Chemistry 13 (9): 2282–2283. doi:10.1021/ic50139a050. 
  11. ^ Kirchheim, R.; Mutschele, T.; Kieninger, W (1988). "Hydrogen in amorphous and nanocrystalline metals". Materials Science and Engineering 99: 457–462. doi:10.1016/0025-5416(88)90377-1. 
  12. ^ Kirchheim, R. (1988). "Hydrogen solubility and diffusivity in defective and amorphous metals". Progress in Materials Science 32 (4): 262–325. doi:10.1016/0079-6425(88)90010-2. 
  13. ^ "Helium: the essentials". WebElements. Retrieved on 2008-07-15.
  14. ^ "Helium: physical properties". WebElements. Retrieved on 2008-07-15.
  15. ^ "Pierre Janssen". MSN Encarta. Retrieved on 2008-07-15.
  16. ^ Theiss, Leslie (2007-01-18). "Where Has All the Helium Gone?". Bureau of Land Management. Retrieved on 2008-07-15.
  17. ^ Timmerhaus, Klaus D. (2006-10-06). Cryogenic Engineering: Fifty Years of Progress. Springer. ISBN 038733324X. 
  18. ^ Copel, M. (September 1966). "Helium voice unscrambling". Audio and Electroacoustics 14 (3): 122–126. 
  19. ^ "helium dating". Encyclopædia Britannica. (2008). 
  20. ^ Brain, Marshall. "How Helium Balloons Work". How Stuff Works. Retrieved on 2008-07-15.
  21. ^ Jiwatram, Jaya (2008-07-10). "The Return of the Blimp". Popular Science. Retrieved on 2008-07-15.
  22. ^ "When good GTAW arcs drift; drafty conditions are bad for welders and their GTAW arcs." (2005-02-01). Welding Design & Fabrication. 
  23. ^ Montgomery, Craig (2006-09-04). "Why does inhaling helium make one's voice sound strange?". Scientific American. Retrieved on 2008-07-15.
  24. ^ "Probable Discovery Of A New, Supersolid, Phase Of Matter". Science Daily (2004-09-03). Retrieved on 2008-07-15.
  25. ^ Browne, Malcolm W. (1979-08-21). "Scientists See Peril In Wasting Helium; Scientists See Peril in Waste of Helium", The New York Times. 
  26. ^ "Helium: geological information". WebElements. Retrieved on 2008-07-15.
  27. ^ Cox, Tony (1990-02-03). "Origin of the chemical elements". New Scientist. Retrieved on 2008-07-15.
  28. ^ "Helium supply deflated: production shortages mean some industries and partygoers must squeak by.", Houston Chronicle (2006-11-05). 
  29. ^ Laurence, William L. (1936-06-17). "CALL EARTH'S AGE 2 1/2 BILLION YEARS; Wilkins and Rayton Report to Scientists, at Rochester, on Extensive Study. 'INFANCY' A LONG PERIOD Time Before Maturity Into Cold Planet Put at 700,000,000 Through Atomic Method.", The New York Times. 
  30. ^ Brown, David (2008-02-02). "Helium a New Target in New Mexico". American Association of Petroleum Geologists. Retrieved on 2008-07-15.
  31. ^ Voth, Greg (2006-12-01). "Where Do We Get the Helium We Use?", The Science Teacher. 

References

v • d • e
Periodic tables
Layouts
Lists of elements by
Groups
1 (Alkalis) · 2 (Alkaline earths) · 3 · 4 · 5 · 6 · 7 · 8 · 9 · 10 · 11 · 12 · 13 · 14 · 15 (Pnictogens) · 16 (Chalcogens) · 17 (Halogens) · 18 (Noble gases)
Periods:
1 · 2 · 3 · 4 · 5 · 6 · 7 · 8
Other element categories
Blocks

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  • This page was last modified on 16 September 2008, at 14:59.

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