Crystallization of silicon dioxide and compositional evolution of the Earth’s core

The Earth’s core is about ten per cent less dense than pure iron (Fe), suggesting that it contains light elements as well as iron. Modelling of core formation at high pressure (around 40–60 gigapascals) and high temperature (about 3,500 kelvin) in a deep magma ocean1, 2, 3, 4, 5 predicts that both silicon (Si) and oxygen (O) are among the impurities in the liquid outer core6, 7, 8, 9. However, only the binary systems Fe–Si and Fe–O have been studied in detail at high pressures, and little is known about the compositional evolution of the Fe–Si–O ternary alloy under core conditions. Here we performed melting experiments on liquid Fe–Si–O alloy at core pressures in a laser-heated diamond-anvil cell. Our results demonstrate that the liquidus field of silicon dioxide (SiO2) is unexpectedly wide at the iron-rich portion of the Fe–Si–O ternary, such that an initial Fe–Si–O core crystallizes SiO2 as it cools. If crystallization proceeds on top of the core, the buoyancy released should have been more than sufficient to power core convection and a dynamo, in spite of high thermal conductivity10, 11, from as early on as the Hadean eon12. SiO2 saturation also sets limits on silicon and oxygen concentrations in the present-day outer core.

The center of the earth and other elements in high pressures

 the earth's  core is about ten per cent less dense than pure iron, that it contains light elements as well as iron.

core formation at high pressureand high temperature in a deep magma ocean1,predicts that  silicon and oxygen are among the impurities in the liquid outer core However.

the binary systems (Fe–Si and Fe–O) have been studied in detail at high pressures. Our results demonstrate that the liquidus field of silicon dioxideis unexpectedly wide at the iron-rich portion of the Fe–Si–O ternary.

debatable questions

1. As scientists say the atom is equal to the they say? 

2. Why did John Dalton have almost all his atomic theory wrong if he was supposed to have made a hypothesis to confirm this?

Isotopos

ARSENIC
ATOMIC NUMBER: 33
GROUP: 15 or V A
ATOMIC MASS: 74.9216
PERIOD: 4

76As

75.922394(2)

1.0942(7)d

2-

660.26MeV

Elemental arsenic occurs in twosolid modifications: yellow, and gray or metallic, with specific gravities of 1.97, and 5.73, respectively. Gray arsenic, the ordinary stable form, hasa m.p. of 817°C (28 atm) and sublimes at 614°C. Several other allotropic forms of arsenic are reported in the literature. It is believed that AlbertusMagnus obtained the element in 1250 A.D. In 1649 Schroeder published two methods of preparing the element. It is found native, in the sulfides realgarand orpiment, as arsenides and sulfarsenides of heavy metals, as the oxide, and as arsenates. Mispickel, arsenopyrite, (FeSAs) is the most commonmineral, from which on heating the arsenic sublimes leaving ferrous sulfide. The element is a steel gray, very brittle, crystalline, semimetallic solid;it tarnishes in air, and when heated is rapidly oxidized to arsenous oxide (As2O3) with the odor of garlic. Arsenic and its compounds are poisonous.

COBALT

60 CO

27

3359.9338171(7)

5.2713(8)

 yβ−, γ60Ni5+

Naturally occurring cobalt (Co) is composed of 1 stable isotope, 59Co. 28 radioisotopes have been characterized with the most stable being 60Co with a half-life of 5.2714 years, 57Co with a half-life of 271.8 days, 56Co with a half-life of 77.27 days, and 58Co with a half-life of 70.86 days. All of the remaining radioactive isotopes have half-lives that are less than 18 hours and the majority of these have half-lives that are less than 1 second. 

Radio

• Science and industry use radioisotopes in a variety of ways to improve productivity and, in some cases, to gain information that cannot be obtained in any other way.
• Sealed radioactive sources are used in industrial radiography, gauging applications and mineral analysis.
• Short-lived radioactive material is used in flow tracing and mixing measurements.
• Various radioactive decay series are used to measure the ages of materials incorporating them.
• Gamma sterilisation is used for medical supplies, some bulk commodities and, increasingly, for food preservation.

Nuclear techniques are increasingly used in science, industry and environmental management. The continuous analysis and rapid response of nuclear techniques, many involving radioisotopes, mean that reliable flow and analytic data can be constantly available. This results in reduced costs with increased product quality.

Helium succumbs to pressure

Helium is a famously inert element, but researchers have made a stable compound from helium and sodium.
Artem Oganov at Stony Brook University in New York and his colleagues used an algorithm to look for potentially stable helium compounds and predicted that Na2He could be made. They demonstrated this experimentally by subjecting thin pieces of sodium and helium gas to high pressures of up to 155 gigapascals. Above 113 GPa, the team noticed the formation of a stable crystalline compound, Na2He, that is expected to remain stable up to at least 1,000 GPa. The crystal structure contains cubes of eight sodium atoms; half of these are filled with helium atoms, and the other half are each occupied by an electron pair, binding the sodium atoms together.
The finding could have implications for the understanding of noble gases, chemical bonding and giant gas planets such as Jupiter, which contain high levels of helium.

my commentary:

one study in the stony brook university showed that the elemnt Helium the second to the periodic table can compound with sodium, other element of the periodic table.

Helium:

the atom number is 2.

the symbol is He.

the atomic mass is 4.0026

Sodium:

the atom number is 11.

the symbol is Na.

the atomic mass is 22.990

they said that can do compounds and predicted that Na2He could be made, also they demostrated with experiment to put together the Helium and the Sodium 

half of these are filled with helium atoms, and the other half are each occupied by an electron pair, 

the atomic theory

mental map