Tag Archives: element

Where did all the elements come from?

Matter is made up of atoms, and each atom is one of (currently) 118 elements. But where did those elements come from?

Note: Each element has a different atomic number (represented by the symbol Z (from the German Zahl for number) which represents the number of protons in the element’s nucleus.

Hydrogen, Helium and Lithium (Z=1 to Z=3)

Hydrogen, helium and lithium were formed in the Big Bang, by a process called Big Bang nucleosynthesis. Unstable radioactive isotopes of beryllium were also formed, but those would quickly decay into other elements or fuse with other stable atoms.

Big Bang nucleosynthesis occurred from about one-tenth of a second to one thousand seconds after the Big Bang and involved the creation of protons and neutrons from the quark-gluon plasma that existed before it, and then the creation of hydrogen, helium and lithium from these protons and neutrons.

Beryllium to Iron (Z=4 to Z=26)

A process called stellar nucleosynthesis, where lighter elements are fused into heavier ones with the release of energy (i.e. an exothermic fusion reaction) is responsible for the creation of the elements from beryllium to nickel. Some nickel-56 and zinc-60 is also produced, but these are unstable and decay quickly to form iron-56 and copper-60. It is the decay of nickel-56 into iron-56 which is responsible for the high amount of iron-56 found in meteorites and planetary cores. (For example, both the Earth’s solid inner core and liquid outer core are composed primarily of an iron-nickel alloy.)

There are a variety of stellar nucleosynthesis processes responsible for the formation of these elements: the alpha and triple-alpha processes and the “burning” of lithium, carbon, neon, oxygen and silicon formed in earlier stages. Stellar nucleosynthesis is also responsible for the creation of more helium via the “burning” of deuterium, the proton-proton chain, and the carbon-nitrogen-oxygen cycle.

Cobalt to Californium (Z=27 to Z=98)

There are three processes responsible for the creation of elements heavier than iron: the S-process, the R-process and the Rp-process (sometimes called the P-process). The S-process (slow neutron capture) occurs in low- to medium-mass stars and is when neutrons emitted by fusion reactions between lighter elements are absorbed by heavy nuclei like iron; this process forms about half of the elements heavier than iron.

The R-process (rapid neutron capture) probably occurs in the core of core-collapse supernovae when electrons are forced back “inside” protons to produce an extremely high flux of neutrons which are rapidly absorbed (hence the name) by heavy nuclei like iron. The R-process forms about half of the elements heavier than iron, and most if not all of the heaviest elements like uranium.

A minority of the heavier elements are formed by the Rp-process (rapid proton capture), and these are all lighter elements (evidence suggests it cannot form elements heavier than tellurium (Z=52). It occurs in very high-temperature hydrogen-rich environments like the outer layers of a star undergoing a core-collapse supernova.

Trace amounts of heavier-than-iron elements with atomic numbers 92 to 99 were, and are, also produced naturally on Earth by radioactive decay processes.

Einsteinium to Ununoctium (Z=99 to Z=118)

Small amounts of the lightest of these elements may be produced as outlined above by the S-, R- and Rp-processes, but the majority of them have only ever been produced artificially, in laboratories, by humans. They are all extremely radioactive and have very short half-lives so only exist for tiny fractions of a second when they are created (e.g. element 118, ununoctium has a half life of about 0.9 milliseconds).

The processes by which these heaviest of the elements are created vary. Einsteinium was first detected as a by-product of the first fusion bomb (H-bomb) test, fermium is formed by bombarding lighter lanthanides with neutrons, and mendelevium by the bombardment of californium by alpha particles. The remaining elements have all been created by smashing together two larger nuclei: for example, ununoctium was first produced by colliding krypton-86 and lead-208.

What do Y, Yb, Tb, Er, Gd, Tm, Sc, Ho, Dy and Lu have in common?

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What do the following ten elements have in common?

  • Yttrium
  • Ytterbium
  • Terbium
  • Erbium
  • Gadolinium
  • Thulium
  • Scandium
  • Holmium
  • Dysprosium
  • Lutetium

The answer (and there is a tiny clue in some of the names) is that all ten elements were isolated from one sample, taken from a mine in the small village of Ytterby in Sweden. All of the elements are rare earth metals which occur in similar locations and have similar properties. This makes their extraction and isolation very difficult and this is where the “rare” in their name comes from.

In 1787 one of the students of Lieutenant Carl Axel Arrhenius found a dark-coloured ore that was much too heavy to be coal. Arrhenius took this ore, which he named “ytterbite”, and sent samples to various chemists for analysis. One of these chemists, Johan Gadolin, determined that ytterbite did indeed contain a previously unknown element and called this element yttrium.

In 1843 Carl Gustav Mosander demonstrated that ytterbite was actually made of three metal oxides, not one as Gadolin had thought. The original name was kept for one of these three parts and the other two elements named terbium and erbium, both after the village of Ytterby where they were found.

Terbium was later demonstrated to be a mixture of terbium and a new element which was named gadolinium in honour of Gadolin. Erbium was demonstrated to be a mixture of erbium and and a new element which was named ytterbium, again after the village of Ytterby.

Erbium was then itself demonstrated to a mixture of three elements: erbium; thulium, named after Thule, a term used by early map makers for the far north where Sweden is located; and holmium, named after the Swedish capital Stockholm. Holmium was then later demonstrated to be a mixture of holmium and dysprosium, which takes its name from the Greek word dysprositos meaning “difficult to get”, reflecting the difficulty found in isolating it.

Ytterbium was demonstrated to be composed of ytterbium and a new element which was named scandium after Scandanavia, and finally ytterbium was split again to yield ytterbium and lutetium.

A diagram showing the order in which the ten elements were isolated.