Actinium is found only in traces in uranium ores as the isotope < sup > 227 </ sup > Ac, which decays with a half-life of 21. 772 years, predominantly emitting beta particles.

Actinium is a soft, silvery-white, radioactive, metallic element.

Actinium, which occurs only in trace amounts, continues the trend in chemical behavior for metals that form tripositive ions with a noble gas configuration ; synthetic lawrencium is calculated and partially shown to be more similar to lutetium and yttrium.

* Actinium is discovered by Andre-Louis Debierne.

< sup > 207 </ sup > Pb is the end of the Actinium series from < sup > 235 </ sup > U.

Actinium has similar chemical properties as lanthanum and other lanthanides, and therefore these elements are difficult to separate when extracting from uranium ores.

* Actinium, a chemical element

* André-Louis Debierne ( 9 °), chemist, discoverer of the element Actinium

Actinium reacts rapidly with oxygen and moisture in air forming a white coating of actinium oxide that prevents further oxidation.

Receipt Date: 31-DEC-55 4358283-Retrieved 2012-01-29 see also: < sup > 228 </ sup > Ac = ( Actinium 228 ) In 1959, he joined the staff of CERN ( European Organization for Nuclear Research ) in Geneva.

Actinium ( Ac ) has no stable isotopes, thus a standard atomic mass cannot be given.

Actinium gave the name to the actinide series, a group of 15 similar elements between actinium and lawrencium in the periodic table.

Scandium, Yttrium, Elements des Terres Rares, Actinium, P. Pascal, Editor, Masson & Cie 1959

The actinide series are the second row of the f-block ( 5f series ) and comprise the elements from Actinium to Lawrencium.

Actinium also has two meta states.

Americium ( ) is a transuranic radioactive chemical element that has the symbol Am and atomic number 95.

Americium is a relatively soft radioactive metal with silvery appearance.

Astatine ( or ) is a radioactive chemical element with the chemical symbol At and atomic number 85.

Astatine is an extremely radioactive element ; all its isotopes have half-lives of less than 12 hours, decaying into bismuth, polonium, radon, or other astatine isotopes.

Astatine is the least reactive of the halogens, being less reactive than iodine ; however, multiple compounds of astatine have been synthesized in microscopic amounts and studied as intensively as possible before their inevitable radioactive disintegration.

Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle ( two protons and two neutrons ) and thereby transforms ( or ' decays ') into an atom with a mass number 4 less and atomic number 2 less.

Alpha decay is much more easily shielded against than other forms of radioactive decay.

The largest natural contributor to public radiation dose is radon, a naturally occurring, radioactive gas found in soil and rock.

For example, the antiparticle of the electron is the positively charged antielectron, or positron, which is produced naturally in certain types of radioactive decay.

* 1964 – A Transit-5bn satellite fails to reach orbit after launch ; as it re-enters the atmosphere, of radioactive plutonium in its SNAP RTG power source is widely dispersed.

Berkelium (, less commonly ), is a transuranic radioactive chemical element with the symbol Bk and atomic number 97, a member of the actinide and transuranium element series.

Berkelium is a soft, silvery-white, radioactive metal.

Berkelium is a soft, silvery-white, radioactive actinide metal.

The number of atoms on the left and the right in the equation for a chemical transformation is equal ( when unequal, the transformation by definition is not chemical, but rather a nuclear reaction or radioactive decay ).

There are three naturally occurring isotopes, with < sup > 12 </ sup > C and < sup > 13 </ sup > C being stable, while < sup > 14 </ sup > C is radioactive, decaying with a half-life of about 5, 730 years.

, 1 million US gallons ( 3, 785 m < sup > 3 </ sup >) of highly radioactive waste is traveling through groundwater toward the Columbia River.

While known for most elements, either or both of these measurements is still undetermined for some of the radioactive elements available in only tiny quantities.

Iron-56 is particularly common, since it is the most stable element that can easily be made from alpha particles ( being a product of decay of radioactive nickel-56, ultimately made from 14 helium nuclei ).

The two natural radioactive isotopes are < sup > 113 </ sup > Cd ( beta decay, half-life is 7. 7 × 10 < sup > 15 </ sup > years ) and < sup > 116 </ sup > Cd ( two-neutrino double beta decay, half-life is 2. 9 × 10 < sup > 19 </ sup > years ).

The drug's chemical name is listed, since most states require feed processors to use this name instead of the trade name on the feed tag.

In some instances, the trade name is shown in parentheses following the chemical name.

Even here there is room for some variation, for metal surfaces vary in smoothness, absorptive capacity, and chemical reactivity.

As is well known, detergent actives belong to the chemical class consisting of moderately high molecular weight and highly polar molecules which exhibit the property of forming micelles in solution.

On chemical grounds it seems most likely that iodide is first converted to Af and then to Af as the active iodinating species.

The chemical nature of the iodocompounds is discussed below ( pp. 76 et seq. ).

It is therefore necessary to consider the properties of pituitary TSH if the fragmentary chemical information about blood TSH is to be discussed rationally.

The importance of knowing in what chemical forms the hormone may exist is accentuated by the recent observation that there exists an abnormally long-acting TSH in blood drawn from many thyrotoxic patients ( Adams, 1958 ).

Whether this abnormal TSH differs chemically from pituitary TSH, or is, alternatively, normal TSH with its period of effectiveness modified by some other blood constituent, cannot be decided without chemical study of the activity in the blood of these patients and a comparison of the substance responsible for the blood activity with pituitary Aj.

The aim is to collect a very broad range of physical, chemical, morphological, and structural data for crystals on an encyclopedic scale and to seek all possible useful and revealing correlations of properties with internal structure.

The process in which the outcome of any one stage is known only statistically is also of interest, although for chemical reactor design it is not as important as the deterministic process.

It is a popular belief that alchemists made contributions to the " chemical " industries of the day — ore testing and refining, metalworking, production of gunpowder, ink, dyes, paints, cosmetics, leather tanning, ceramics, glass manufacture, preparation of extracts, liquors, and so on ( it seems that the preparation of aqua vitae, the " water of life ", was a fairly popular " experiment " among European alchemists ).

Experiments have been conducted to attempt the synthesis of ununennium ( Uue ), which is likely to be the next member of the group, but they have all met with failure .< ref name =" link "> However, ununennium may not be an alkali metal due to relativistic effects, which are predicted to have a large influence on the chemical properties of superheavy elements.

Each element has a specific set of chemical properties as a consequence of the number of electrons present in the neutral atom, which is Z ( the atomic number ).

The number of electrons in each element's electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior.

Hence it is the atomic number alone that determines the chemical properties of an element ; and it is for this reason that an element can be defined as consisting of any mixture of atoms with a given atomic number.

Argon ( ) is a chemical element with symbol Ar and atomic number 18.

The name " argon " is derived from the Greek word αργον meaning " lazy " or " the inactive one ", a reference to the fact that the element undergoes almost no chemical reactions.

Arsenic ( ) is a chemical element with symbol As and atomic number 33.

Antimony ( or ; ) is a toxic chemical element with symbol Sb and atomic number 51.