Americium is a synthetic radioactive chemical element with the symbol Am and atomic number 95. It is a transuranic member of the actinide series, in the periodic table located under the lanthanide element europium, and thus by analogy was named after the Americas.
The actinide or actinoid series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium. The actinide series derives its name from the first element in the series, actinium. The informal chemical symbol An is used in general discussions of actinide chemistry to refer to any actinide.
Curium is a transuranic, radioactive chemical element with the symbol Cm and atomic number 96. This actinide element was named after eminent scientists Marie and Pierre Curie, both known for their research on radioactivity. Curium was first intentionally made by the team of Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso in 1944, using the cyclotron at Berkeley. They bombarded the newly discovered element plutonium with alpha particles. This was then sent to the Metallurgical Laboratory at University of Chicago where a tiny sample of curium was eventually separated and identified. The discovery was kept secret until after the end of World War II. The news was released to the public in November 1947. Most curium is produced by bombarding uranium or plutonium with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains ~20 grams of curium.
Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, a ligand, a nucleophile, and a catalyst. The hydroxide ion forms salts, some of which dissociate in aqueous solution, liberating solvated hydroxide ions. Sodium hydroxide is a multi-million-ton per annum commodity chemical. The corresponding electrically neutral compound HO• is the hydroxyl radical. The corresponding covalently bound group –OH of atoms is the hydroxy group. Both the hydroxide ion and hydroxy group are nucleophiles and can act as catalysts in organic chemistry.
Neptunium is a chemical element with the symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element. Its position in the periodic table just after uranium, named after the planet Uranus, led to it being named after Neptune, the next planet beyond Uranus. A neptunium atom has 93 protons and 93 electrons, of which seven are valence electrons. Neptunium metal is silvery and tarnishes when exposed to air. The element occurs in three allotropic forms and it normally exhibits five oxidation states, ranging from +3 to +7. It is radioactive, poisonous, pyrophoric, and capable of accumulating in bones, which makes the handling of neptunium dangerous.
The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). The elements have very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure.
Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, that dissolves in water as K+ and MnO−
4, an intensely pink to purple solution.
Chromate salts contain the chromate anion, CrO2−
4. Dichromate salts contain the dichromate anion, Cr
2O2−
7. They are oxyanions of chromium in the +6 oxidation state and are moderately strong oxidizing agents. In an aqueous solution, chromate and dichromate ions can be interconvertible.
Barium hydroxide is a chemical compound with the chemical formula Ba(OH)2. The monohydrate (x = 1), known as baryta or baryta-water, is one of the principal compounds of barium. This white granular monohydrate is the usual commercial form.
Ferrate(VI) is the inorganic anion with the chemical formula [FeO4]2−. It is photosensitive, contributes a pale violet colour to compounds and solutions containing it and is one of the strongest water-stable oxidizing species known. Although it is classified as a weak base, concentrated solutions containing ferrate(VI) are corrosive and attack the skin and are only stable at high pH.
Xenon trioxide is an unstable compound of xenon in its +6 oxidation state. It is a very powerful oxidizing agent, and liberates oxygen from water slowly, accelerated by exposure to sunlight. It is dangerously explosive upon contact with organic materials. When it detonates, it releases xenon and oxygen gas.
Environmental radioactivity is not limited to actinides; non-actinides such as radon and radium are of note. While all actinides are radioactive, there are a lot of actinides or actinide-relating minerals in the Earth's crust such as uranium and thorium. These minerals are helpful in many ways, such as carbon-dating, most detectors, X-rays, and more.
Barium ferrate is the chemical compound of formula BaFeO4. This is a rare compound containing iron in the +6 oxidation state. The ferrate(VI) ion has two unpaired electrons, making it paramagnetic. It is isostructural with BaSO4, and contains the tetrahedral [FeO4]2− anion.
Neptunium(IV) oxide, or neptunium dioxide, is a radioactive, olive green cubic crystalline solid with the formula NpO2. It emits both α- and γ-particles.
Neptunium(VI) fluoride (NpF6) is the highest fluoride of neptunium, it is also one of seventeen known binary hexafluorides. It is an orange volatile crystalline solid. It is relatively hard to handle, being very corrosive, volatile and radioactive. Neptunium hexafluoride is stable in dry air but reacts vigorously with water.
Many compounds of thorium are known: this is because thorium and uranium are the most stable and accessible actinides and are the only actinides that can be studied safely and legally in bulk in a normal laboratory. As such, they have the best-known chemistry of the actinides, along with that of plutonium, as the self-heating and radiation from them is not enough to cause radiolysis of chemical bonds as it is for the other actinides. While the later actinides from americium onwards are predominantly trivalent and behave more similarly to the corresponding lanthanides, as one would expect from periodic trends, the early actinides up to plutonium have relativistically destabilised and hence delocalised 5f and 6d electrons that participate in chemistry in a similar way to the early transition metals of group 3 through 8: thus, all their valence electrons can participate in chemical reactions, although this is not common for neptunium and plutonium.
Neptunium(IV) nitrate is an inorganic compound, a salt of neptunium and nitric acid with the chemical formula Np(NO3)4. The compound forms gray crystals, dissolves in water, and forms crystal hydrates.
Neptunium compounds are compounds containg the element neptunium (Np). Neptunium has five ionic oxidation states ranging from +3 to +7 when forming chemical compounds, which can be simultaneously observed in solutions. It is the heaviest actinide that can lose all its valence electrons in a stable compound. The most stable state in solution is +5, but the valence +4 is preferred in solid neptunium compounds. Neptunium metal is very reactive. Ions of neptunium are prone to hydrolysis and formation of coordination compounds.
Plutonium compounds are compounds containing the element plutonium (Pu). At room temperature, pure plutonium is silvery in color but gains a tarnish when oxidized. The element displays four common ionic oxidation states in aqueous solution and one rare one:
Technetium(IV) oxide, also known as technetium dioxide, is a chemical compound with the formula TcO2 which forms the dihydrate, TcO2·2H2O, which is also known as technetium(IV) hydroxide. It is a radioactive black solid which slowly oxidizes in air.
