In chemistry, the pure substance is a very simple concept to grasp. It’s a substance made of only one type of atom or only one type of molecule (a cluster of atoms bonded together). A pure substance can be classified as an element or a compound. An element contains only one kind of...
Through the years, we’ve become much more precise in our timekeeping. Today’s standard for precision are atomic clocks that measure thevibration of atomsvia a quartz crystal oscillator. And they are incredibly accurate: Some are calculated to be off by only 1 second over the course of the ...
The Atomic Packing Factor (APF) is essentially the density of the unit cell. Since we use the hard sphere model, each point inside the cell is either part of an atom, or part of the void. APF is basically the fraction of atoms to void. For a full article explaining APF, check out ...
Diborane is an unusual molecule with two boron atoms bonded to four terminal hydrogen atoms and two bridging hydrogen atoms. This has puzzled many scientists and gave rise to many theories, with no final definitive explanation. This article brings a simple explanation of the bond lengths and angle...
If the example sentences are out of date, editors need to have experiences and make n___4___ examples. “To give a correct explanation of the word ‘焗油(deep condition)’, one editor went to a barber shop to experience it for himself,” Yu told the Beijing Times. So far, ...
Global warming is working a bit like this. Thanks to a variety of things that people do, Earth is getting slightly warmer year by year. It's not really warming up noticeably—at least not in the short term. In fact, since 1900, the whole planet has warmed up only by around 1.1 degre...
The use of the simpler formula, relying only on the expectation value of the dipole momentum operator, is well justified if one is interested in the situation when light is scattered by many atoms with uncorrelated dipole momenta39, which effectively ensures validity of the decorrelation assumption...
Thus it is far from physically obvious why the HS explanation of quasi-universal structure extends to the dynamics. Moreover, while the HS explanation does account for the finding that, for example, the Gaussian-core model15,35,36 violates quasi-universality—a model without harsh repulsions ...
The basic principle of operation of EDX begins when the surface of a material is “illuminated” with a beam of electrons. Said illumination beam causes the expulsion of secondary electrons from the atoms that make up the sample. The ejected electrons leave vacancies in the lower energy levels ...
In a water molecule, the oxygen atom has two lone pairs of electrons, each of which can act as a hydrogen bond acceptor. The two hydrogen atoms in water can each be “donated” to another acceptor atom (such as the oxygen atom on another water molecule). ...