But not every magic number is detailed in a textbook; researchers are still finding more. This week, a team of US and British scientists report in Nature 1 that radioactive silicon, an artificial element with 14 protons and 28 neutrons, also seems to be doubly magic. This is the case in the most common form of silicon, which has 14 protons and 14 neutrons.
But nuclei grow and change shape as more subatomic particles are packed in, and this changes the relative location of their energy levels. Paul Cottle, a nuclear physicist from Florida State University, Tallahassee, and the rest of the study's international team had reason to believe that as silicon gets beefed up with neutrons, this would alter the energy levels in a way that would make 14 a magic number. To test this idea, the team fired a high-energy beam of sulphur at a beryllium target.
This forced the sulphur nuclei to lose two protons, transmuting them to silicon. They counted how much silicon was produced by the collisions, and compared this with quantum mechanical calculations that assumed 14 was magic. The numbers matched up perfectly, says Tostevin. The calculations throw up some surprises. It seems odd, for example, that 28 remains a magic number for neutrons in the silicon nucleus, says Robert Janssens, a nuclear physicist at Argonne National Laboratory, Illinois.
Finding out where the magic stops working is the key to exploring the most neutron-rich isotopes, Janssens explains.
Understanding how the energy levels of nuclei are arranged is an important test of quantum theory, says Tostevin. It could help to reveal the sequence of nuclear reactions that occur in supernova explosions, he adds. Glossary Common oxidation states The oxidation state of an atom is a measure of the degree of oxidation of an atom. Oxidation states and isotopes. Glossary Data for this section been provided by the British Geological Survey.
Relative supply risk An integrated supply risk index from 1 very low risk to 10 very high risk. Recycling rate The percentage of a commodity which is recycled.
Substitutability The availability of suitable substitutes for a given commodity. Reserve distribution The percentage of the world reserves located in the country with the largest reserves. Political stability of top producer A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators.
Political stability of top reserve holder A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators.
Supply risk. Young's modulus A measure of the stiffness of a substance. Shear modulus A measure of how difficult it is to deform a material. Bulk modulus A measure of how difficult it is to compress a substance. Vapour pressure A measure of the propensity of a substance to evaporate. Pressure and temperature data — advanced. Listen to Silicon Podcast Transcript :. You're listening to Chemistry in its element brought to you by Chemistry World , the magazine of the Royal Society of Chemistry.
For this week's element we enter the world of science fiction to explore life in outer space. Here's Andrea Sella. When I was about 12, my friends and I went through a phase of reading science fiction. There the were the fantastic worlds of Isaac Asimov, Larry Niven and Robert Heinlein, involving impossible adventures on mysterious planets - the successes of the Apollo space programme at the time only helped us suspend our disbelief.
One of the themes I remember from these stories was the idea that alien life forms, often based around the element silicon, abounded elsewhere in the universe. Why silicon? Well, it is often said that elements close to each other in the periodic table share similar properties and so, seduced by the age-old red herring that "carbon is the element of life", the writers selected the element below it, silicon.
I was reminded of these readings a couple of weeks ago when I went to see an exhibition of work by a couple of friends of mine. Called "Stone Hole" it consisted of stunning panoramic photographs taken at extremely high resolution inside sea caves in Cornwall.
As we wandered through the gallery a thought occurred to me. Silicate rocks - those in which silicon is surrounded tetrahedrally by four oxygen atoms - exist in an astonishing variety, the differences being determined by how the tetrahedra building blocks link together, and what other elements are present to complete the picture. When the tetrahedra link one to the next, one gets a mad tangle of chains looking like an enormous pot of spaghetti - the sorts of structures one gets in ordinary glass.
The purest of these chain-like materials is silicon dioxide - silica - found quite commonly in nature as the colourless mineral quartz or rock crystal. In good, crystalline quartz, the chains are arranged in beautiful helices and these can all spiral to the left. Or to the right. When this happens the crystals that result are exact mirror images of each other. But not superimposable - like left and right shoes. To a chemist, these crystals are chiral, a property once thought to be the exclusive property of the element carbon, and chirality, in turn, was imagined to be a fundamental feature of life itself.
Yet here it is, in the cold, inorganic world of silicon. Most grandiose of all, one can make porous 3D structures - a bit like molecular honeycombs - particularly in the presence of other tetrahedral linkers based on aluminium.
These spectacular materials are called the zeolites, or molecular sieves. By carefully tailoring the synthetic conditions, one can build material in which the pores and cavities have well defined sizes - now you have a material that can be used like a lobster traps, to catch molecules or ions of appropriate size.
But what of the element itself? Freeing it from oxygen is tough, it hangs on like grim death and requires brutal conditions. It was Humphrey Davy, the Cornish chemist and showman, who first began to suspect that silica must be a compound, not an element. He applied electric currents to molten alkalis and salts and to his astonishment and delight, isolated some spectacularly reactive metals, including potassium. He now moved on to see what potassium could do. Passing potassium vapour over some silica he obtained a dark material that he could then burn and convert back to pure silica.
Where he pushed, others followed. Silicon's properties are neither fish nor fowl. Dark gray in colour and with a very glossy glass-like sheen, it looks like a metal but is in fact quite a poor conductor of electricity, and there in many ways, lies the secret of its ultimate success. The problem is that electrons are trapped, a bit like pieces on a draughts board in which no spaces are free. What makes silicon, and other semiconductors, special is that it is possible to promote one of the electrons to an empty board - the conduction band - where they can move freely.
It's a bit like the 3-dimensional chess played by the point-eared Dr Spock in Star Trek. Temperature is crucial. Warming a semiconductor, allow some electrons to leap, like salmon, up to the empty conduction band. And at the same time, the space left behind - known as a hole - can move too. But there is another way to make silicon conduct electricity: it seems perverse, but by deliberately introducing impurities like boron or phosphorus one can subtly change the electrical behaviour of silicon.
Such tricks lie at the heart of the functioning of the silicon chips that allow you to listen to this podcast. In less than 50 years silicon has gone from being an intriguing curiosity to being one of the fundamental elements in our lives. But the question remains, is silicon's importance simply restricted to the mineral world? The prospects do not seem good - silicate fibres, like those in blue asbestos are just the right size to penetrate deep inside the lungs where they pierce and slash the inner lining of the lungs.
And yet, because of its extraordinary structural variability, silicon chemistry has been harnessed by biological systems. Silicate shards lurk in the spines of nettles waiting to score the soft skin of the unwary hiker and inject minuscule amounts of irritant.
And in almost unimaginable numbers delicate silicate structures are grown by the many tiny life-forms that lie at the base of marine food chains, the diatoms. Could one therefore find silicon-based aliens somewhere in space? My hunch would probably be not. Certainly not as the element. It is far too reactive and one will always find it associated with oxygen. But even linked with oxygen, it seems unlikely, or at least not under the kinds of mild conditions that we find on earth.
But then again, there is nothing like a surprise to make one think. The number of protons , neutrons, and electrons in an atom can be determined from a set of simple rules. The number of protons in the nucleus of the atom is equal to the atomic number Z. The number of electrons in a neutral atom is equal to the number of protons. The average silicon atom has fourteen protons , fourteen electrons, and most have 14 neutrons.
This is a digram of a silicon atom. This shows the 14 protons in the nucleus and where the 14 electrons are located. The four electron, highlighted in green, that are located in the outer ring are the valence electrons. The atomic number is equal to the number of protons in the atom, therefore silicon has 14 protons. In a neutral species, the number of protons equals the number of electrons so silicon also has 14 electrons.
The mass number is the number of protons plus neutrons, therefore 28 — 14 protons equal 14 neutrons. Asked by: Marya Tarquini asked in category: General Last Updated: 27th April, What is the number of protons neutrons and electrons in silicon? Answer and Explanation: Silicon has 14 protons, 14 neutrons and 14 electrons.
The atomic number is equal to the number of protons, since so is the atomic numberHow do we find the number of protons, electrons and neutrons? The structure of the atom. The number of protons, neutrons and electrons in an atom can be determined by a simple set of rules. The number of protons in the atomic nucleus equals the atomic number Z. The number of electrons in a neutral atom equals the number of protons. Where are the protons and neutrons in silicon?
The average silicon atom has fourteen protons, fourteen electrons, and most have 14 neutrons. It is a diagram of a silicon atom.
0コメント