Elements
108 questions tagged Elements — spanning every one of the seven Ws.
Which Element Is the Most Reactive?
Fluorine is the most reactive element, reacting violently with virtually every other element and compound — it is the most electronegative element on the periodic table and the strongest known oxidising agent.
Which Metal Is the Lightest?
Lithium is the lightest metal, with a density of just 0.534 g/cm3 — so light it floats on water (and even on some oils) — and it is also the lightest solid element.
Which Is the Densest Element?
Osmium is the densest naturally occurring element, at about 22.59 grams per cubic centimetre.
Which element has the highest atomic number?
Oganesson, element 118 (symbol Og), has the highest atomic number of any element discovered so far.
What is a noble gas?
A noble gas is one of the elements in Group 18 of the periodic table. These gases are very unreactive because their outer electron shells are full.
What is an alkali metal?
An alkali metal is a Group 1 element such as lithium, sodium, or potassium. These metals are highly reactive because they have one valence electron.
What is a halogen?
A halogen is a Group 17 element on the periodic table. Halogens are very reactive nonmetals that often form salts with metals.
What is a transition metal?
A transition metal is an element in the central block of the periodic table, usually Groups 3 through 12. Many transition metals are known for multiple oxidation states and colored compounds.
When was the element helium first discovered on Earth?
Helium was first identified on Earth in 1895.
When was neon first isolated and named?
Neon was first isolated and named in 1898.
When was radon first identified as a distinct element?
Radon was identified in the late 1890s, with its radioactive nature clarified in 1900.
When was chlorine first identified as an element?
Chlorine was identified as an element in 1810.
When was silicon first isolated in pure form?
Silicon was first isolated in 1824.
When was the element technetium first discovered?
Technetium was first identified in 1937.
Where was argon first discovered?
Argon was first identified in London, England, in 1894. It was found in the atmosphere as an unreactive gas.
Where was neon first discovered?
Neon was first discovered in London, England, in 1898. It was isolated from liquid air by William Ramsay and Morris Travers.
Where was krypton first discovered?
Krypton was first discovered in London, England, in 1898. It was isolated from liquid air by William Ramsay and Morris Travers.
Where was xenon first discovered?
Xenon was first discovered in London, England, in 1898. It was isolated from liquid air by William Ramsay and Morris Travers.
Where was radon first recognized as a distinct chemical element?
It was first identified in Europe in the early 1900s, with key work in Germany and Austria. Radon was recognized as a radioactive gas produced from radium.
Where was the element astatine first synthesized?
Astatine was first synthesized in Berkeley, California, in 1940. It was made by bombarding bismuth with alpha particles.
Where was gadolinium first discovered?
It was first discovered in Paris, France, in 1880. It was named after the Finnish chemist Johan Gadolin.
Where was the element francium first discovered?
It was first identified in Paris, France, in 1939. Marguerite Perey discovered it while studying actinium decay.
Where was the first synthetic element created?
It was first made in the Berkeley cyclotron laboratory in California in 1937. Technetium was the first element produced artificially.
Which element has the highest density?
Osmium is commonly cited as the densest naturally occurring element, with a density of about 22.59 g/cm³. Iridium is very close, and the exact ranking can depend on temperature and crystal structure.
Which element has the lowest density among solids at room temperature?
Lithium is the least dense solid element at room temperature, with a density of about 0.53 g/cm³. It is so light that it floats on water, although it reacts with water at the same time.
Which element has the largest atomic number in nature?
Uranium is the heaviest naturally occurring element with atomic number 92. Elements beyond uranium are mostly synthetic and made in laboratories.
Which element has the highest atomic weight among stable elements?
Lead is the heaviest stable element by atomic weight, with an average atomic mass of about 207.2 u. It sits near the end of the periodic table and is notable for its high density and historical uses.
Whose work discovered a noble gas by fractionating liquid air?
Sir William Ramsay discovered argon in 1894, and later helped identify several other noble gases. Argon became the first noble gas found on Earth.
Whose discovery of helium began with a solar eclipse?
Helium was first identified in the Sun’s spectrum by Pierre Janssen and Norman Lockyer in 1868. It was isolated on Earth later, in 1895, by Sir William Ramsay.
Whose work led to the discovery of the noble gas neon?
Neon was discovered in 1898 by William Ramsay and Morris Travers. It was isolated from liquefied air and named from the Greek word for “new.”
Whose research revealed the element krypton?
William Ramsay and Morris Travers discovered krypton in 1898. They found it among the residual gases left after liquefying air.
Whose discovery revealed xenon in the atmosphere?
William Ramsay and Morris Travers discovered xenon in 1898. It was the last of the naturally occurring noble gases found in air.
Whose work discovered protactinium?
Lise Meitner and Otto Hahn are credited with discovering protactinium in 1917. It was one of the last long-sought missing pieces in the uranium decay series.
Whose discovery revealed rhenium?
Walter Noddack, Ida Tacke Noddack and Otto Berg discovered rhenium in 1925. It was the last stable element to be found in nature.
What is an allotrope?
An allotrope is a different structural form of the same element in the same physical state. Carbon is famous for allotropes such as diamond and graphite.
When was helium first discovered in the Sun?
In 1868, helium was first identified in the Sun’s spectrum during a solar eclipse.
When was gallium discovered?
Gallium was discovered in 1875 by French chemist Paul-Émile Lecoq de Boisbaudran. It was one of the first elements predicted by Mendeleev to be found later.
When was germanium discovered?
Germanium was discovered in 1886 by Clemens Winkler. Mendeleev had predicted it years earlier as eka-silicon.
When was technetium first discovered?
Technetium was first identified in 1937 by Carlo Perrier and Emilio Segrè. It was the first element to be artificially produced rather than found naturally in useful amounts.
When was astatine first discovered?
Astatine was first identified in 1940 by Dale Corson, Kenneth MacKenzie, and Emilio Segrè. It was the last naturally occurring element to be discovered.
When was neptunium first discovered?
Neptunium was first produced and identified in 1940 by Edwin McMillan and Philip Abelson. It was the first transuranium element discovered.
When was plutonium first discovered?
Plutonium was first produced in 1940 and identified in 1941 by Glenn T. Seaborg, Edwin McMillan, Joseph Kennedy, and Arthur Wahl. It was the second transuranium element discovered.
When was helium first discovered on Earth?
Helium was first detected on Earth in 1895 by William Ramsay. It had already been observed in the Sun’s spectrum in 1868.
When was neon first discovered?
Neon was discovered in 1898 by William Ramsay and Morris Travers. They isolated it from liquid air.
When was argon discovered?
Argon was discovered in 1894 by Lord Rayleigh and William Ramsay. It was the first noble gas identified.
When was radon discovered?
Radon was identified in the early 1900s, with Ernest Rutherford and Robert B. Owens discovering radon-emanation in 1900. The element was later recognized as a noble gas.
When was chlorine discovered?
Chlorine was discovered in 1774 by Carl Wilhelm Scheele. It later became recognized as an element by Humphry Davy in 1810.
When was sodium discovered as a distinct element?
Sodium was isolated as an element in 1807 by Humphry Davy. He used electrolysis to separate it from compounds.
When was uranium discovered?
Uranium was discovered in 1789 by Martin Heinrich Klaproth. It was named after the planet Uranus.
When was platinum first recognized as a distinct element in Europe?
Platinum was recognized in Europe in the mid-1700s, with Antonio de Ulloa publishing a description in 1748. It was long known in South America before that.
Where are the lanthanides placed on the periodic table?
They are usually shown in a separate row below the main body of the periodic table. They are elements 57 through 71, from lanthanum to lutetium.
Where are the actinides placed on the periodic table?
They are typically shown in a separate row below the lanthanides. The actinide series runs from actinium to lawrencium, elements 89 through 103.
Where is hydrogen placed on the periodic table?
Hydrogen is usually shown at the top left of the table, above the alkali metals. Its placement is unusual because it behaves unlike most other elements in the same column.
Where is helium placed on the periodic table?
Helium sits in the top right of the periodic table, above the noble gases. Its position reflects its chemical inertness, even though its electron structure is unusual.
Where is carbon placed on the periodic table?
Carbon is in group 14, period 2 of the periodic table. It sits between boron and nitrogen and is the backbone of organic chemistry.
Where is iron placed on the periodic table?
Iron is in period 4, group 8 of the periodic table. It is one of the best-known transition metals and has atomic number 26.
Where is gold placed on the periodic table?
Gold is in group 11, period 6 of the periodic table. Its atomic number is 79, and it is one of the least reactive and most valued metals.
Where is mercury placed on the periodic table?
Mercury is in group 12, period 6 of the periodic table. It is atomic number 80 and is famous for being liquid at room temperature.
Where is oxygen placed on the periodic table?
Oxygen is in group 16, period 2 of the periodic table. It has atomic number 8 and is essential for respiration and combustion.
Where is sodium placed on the periodic table?
Sodium is in group 1, period 3 of the periodic table. It has atomic number 11 and is one of the classic alkali metals.
Where is chlorine placed on the periodic table?
Chlorine is in group 17, period 3 of the periodic table. It has atomic number 17 and is a highly reactive halogen.
Where is neon placed on the periodic table?
Neon is in group 18, period 2 of the periodic table. It has atomic number 10 and is one of the noble gases used in lighting.
Where is uranium placed on the periodic table?
Uranium is in the actinide series, usually shown in the bottom row of the periodic table. It has atomic number 92 and is the best-known naturally occurring heavy radioactive element.
Where is plutonium placed on the periodic table?
Plutonium is in the actinide series, typically placed in the bottom row of the periodic table. Its atomic number is 94, and it is a man-made radioactive element.
Where are synthetic elements found on the periodic table?
They are generally found at the bottom-right region of the table and in the transuranic part of the actinide series. Most have atomic numbers above 92 and are made in laboratories.
Where are the rare earth elements found on the periodic table?
They are mainly the lanthanides, usually shown in the separate row below the main table. Scandium and yttrium are often grouped with them because of similar chemistry.
Whose discovery made fluorine the most reactive element on the periodic table?
Henri Moissan’s. In 1886 he isolated fluorine, one of the most reactive elements known.
Whose discovery established chlorine as a distinct element rather than a compound?
Carl Wilhelm Scheele’s. In 1774 he prepared chlorine, and later chemists confirmed it was an element.
Whose discovery first revealed the element technetium?
Perrier and Segre’s. In 1937 they produced technetium, the first element made artificially.
Whose work identified iodine as a new element through a violet vapor?
Bernard Courtois’s. In 1811 he discovered iodine while processing seaweed ash.
Whose discovery made bromine the only nonmetal liquid at room temperature after mercury?
Antoine Jérôme Balard’s. In 1826 he discovered bromine, a reddish-brown liquid element.
Whose discovery of manganese dioxide helped unlock oxygen chemistry?
Carl Wilhelm Scheele’s and Joseph Priestley’s work did. They prepared oxygen in the 1770s from heated compounds including manganese dioxide.
What is a rare earth element?
A rare earth element is one of 17 metals that are important in electronics, magnets, and advanced materials. They are not always rare, but they are often dispersed and difficult to mine in concentrated form.
When was helium first identified as an element on Earth?
Helium was first identified on Earth in 1895. It was isolated from the uranium mineral cleveite by William Ramsay.
When was lithium discovered?
Lithium was discovered in 1817 by Johan August Arfwedson. He found it while analyzing the mineral petalite.
When was barium first isolated?
Barium was first isolated in 1808 by Humphry Davy. He obtained it using electrolysis of barium compounds.
When was cadmium discovered?
Cadmium was discovered in 1817 by Friedrich Stromeyer. He found it in zinc carbonate impurities.
When was cobalt named and recognized as a distinct metal?
Cobalt was named in 1735 by Georg Brandt, who proved that it was the source of the blue color in certain ores. It became one of the first metals identified scientifically in modern chemistry.
When was platinum first scientifically described in Europe?
Platinum was first scientifically described in 1557 by Julius Caesar Scaliger. He wrote about a metal from the Americas that could not be melted easily.
When was gold first discovered to be an element rather than a compound?
Gold was recognized as a chemical element in the earliest days of modern chemistry, but its elemental nature was already understood in antiquity. The key scientific milestone was not discovery, but later classification in the periodic table.
When was the first synthetic element created?
Technetium was the first element made artificially in 1937. It was produced by Carlo Perrier and Emilio Segrè from molybdenum bombardment samples.
When was the transuranium element series first started?
The transuranium era began in 1940, when neptunium and plutonium were first produced. These elements have atomic numbers greater than uranium’s 92.
Whose discovery of bromine revealed one of the few elements liquid at room temperature?
Antoine Jérôme Balard’s. In 1826, he discovered bromine, a reddish-brown liquid element at room temperature.
Whose work first revealed that iodine is a chemical element, not a compound?
Bernard Courtois’s. In 1811, he discovered iodine while processing seaweed ash for saltpeter.
Whose discovery first identified selenium as a new element with properties like sulfur and tellurium?
Jöns Jacob Berzelius’s. In 1817, he discovered selenium while analyzing impurities in sulfuric acid production.
Whose discovery first isolated fluorine, the most reactive element?
Henri Moissan’s. In 1886, he isolated fluorine by electrolyzing a mixture of hydrogen fluoride and potassium fluoride.
Whose work first isolated the rare earth elements and helped define them as a chemical family?
Carl Gustaf Mosander’s. In the 1830s and 1840s, he separated new rare earth elements such as lanthanum, erbium, and terbium.
Whose work first identified cerium as a new element, now the most abundant rare earth element?
Jöns Jacob Berzelius, Wilhelm Hisinger, and Martin Klaproth’s work led to cerium’s identification in 1803.
Whose work first isolated promethium, one of the rarest naturally occurring elements?
Marinlynn, or rather Jacob A. Marinsky, Lawrence E. Glendenin, and Charles D. Coryell’s. In 1945, they identified promethium from fission products.
Whose discovery first established hydrogen as a separate element from air and phlogiston-era chemistry?
Henry Cavendish’s. In 1766, he described hydrogen as a distinct gas and showed it forms water when burned.
How many protons does an element need to be gold?
Gold always has 79 protons. The number of protons is what defines the element.
How many protons does carbon always have?
Carbon always has 6 protons. That is why every carbon atom is the same element, even if its isotopes have different masses.