Chemistry
Fundamental Particles
Fundamental particles are the basic building blocks of matter and are categorized into two main types: quarks and leptons. Quarks combine to form protons and neutrons, while leptons include electrons and neutrinos. These particles are the smallest known units of matter and are essential for understanding the structure and behavior of atoms and molecules.
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9 Key excerpts on "Fundamental Particles"
eBook - ePub- Linus Pauling(Author)
- 2014(Publication Date)
- Dover Publications(Publisher)
25 The Chemistry of the Fundamental Particles During recent years there has been a great increase in our knowledge of the world. Atoms have been found to consist of electrons and nuclei, and the atomic nuclei have been found to consist of protons and neutrons. Moreover, in addition to the electron, the proton, and the neutron, many other particles classed as fundamental have been discovered. The field of science dealing with the nature and the reactions of the Fundamental Particles is developing very rapidly at the present time. Work in this field of science has been carried out largely by physicists, but the reactions by means of which the Fundamental Particles are created, converted into others, and destroyed are in a general way similar to chemical reactions, and we may be justified in considering the study of these reactions and the properties of the Fundamental Particles themselves as constituting the field of the chemistry of the Fundamental Particles. In the following paragraphs we shall describe 34 particles as Fundamental Particles. This number includes 6 (the photon, the graviton, two neutrinos, and two antineutrinos) that move only with the speed of light, and 28 that move only at speeds less than the speed of light. In accordance with the theory of relativity, the particles that move only at the speed of light have zero rest-mass, whereas the others have finite rest-mass. Much of the knowledge about the Fundamental Particles has been obtained during the last decade. The scientists who have been working in this field have made many completely unexpected discoveries, which are changing our ways of thinking about the world
eBook - PDF- SachchidaNand Shukla(Author)
- 2023(Publication Date)
- Arcler Press(Publisher)
In this state, they behave like a single super atom. This enables one to conduct fundamental checks of their quantum mechanical behavior. 1.4. PARTICLES According to physical sciences, particles are defined as small localized objects that have been ascribed various chemical or physical properties. Some of these properties include mass, density, or volume. Particles may vary in quantity or size. There are subatomic particles which include the electron, microscopic particles such as molecules and atoms, macroscopic particles such as powders and granular materials (Amsler et al., 2008). Particles have been used in several experiments to create scientific models of large objects. Particles used in creating these models are chosen depending of their density. The term particle is generally used in various though its definition is refined according to the scientific field. The term particulate is used to refer to any object made up of particles (Figure 1.8). Basic Constituents of Matter 13 Figure 1.8. Particles are formed through combination of subatomic particles. Source: https://www.livescience.com/65427-fundamental-elementary-particles. html. Fundamental particle or elementary particle is a term used in particle physics to refer to a subatomic particle that is not composed of other particles. Some of the particles assumed to be elementary include antimatter particles, fundamental bosons, matter particles and fundament fermions. Examples of fundamental fermions include leptons, antileptons, quarks, and antiquarks. Higgs boson and gauge bosons are fundamental bosons and are force particles involved in the mediation of interactions between fermions. A composite particle is on that has two or more elementary particles. Naturally, matter contains atoms. The atoms were once presumed to be elementary particles. The Greek term atomos was used to mean that it is unable to cut.
eBook - PDFChemistry for Technologists
The Commonwealth and International Library: Electrical Engineering Division
- G. R. Palin, N. Hiller(Authors)
- 2014(Publication Date)
- Pergamon(Publisher)
SECTION II STRUCTURAL CHEMISTRY This page intentionally left blank CHAPTER 2 Atomic Structure Fundamental Particles The original concept of the atom was that it was an indivisible entity, and that the different atoms which occurred in nature were the basic units from which all matter was made. Later, when it was found that the atom was divisible, it was concluded that each atom was made up from pro-tons, neutrons and electrons as stated in Section I. These were called Fundamental Particles, and it seemed that all matter was made up from these three basic units, combined first into atoms of the various elements, which in turn combined to give all other substances. More recently many more sub-atomic particles have been discovered, and these are also called fundamental. The use of this term in this context has also changed. It is now used to denote particles whose structure is not understood in detail, although there is evidence of a structure for many of them, including pro-tons and neutrons. Despite these more recent discoveries, the picture of the atom as a central nucleus of protons and neutrons surrounded by a cloud of electrons is adequate for most studies outside some specialist fields of physics. Isotopes As stated in Section I, the number of protons in an atom is the atomic number and equals the number of electrons. Atoms with atomic numbers from one to ninety-two occur naturally, and others with higher atomic numbers have been made artificially by nuclear reactions. The volume of the region occupied by the nucleus is very small compared with that oc-cupied by the electrons, and the effect of the nucleus on the electrons due to its mass is negligible compared with its effect due to its charge. The ar-rangement of the electrons in an atom is determined mainly by the charge on the nucleus and the number of electrons, and as these are both equal to the atomic number, all atoms with the same atomic number have the same electron arrangement.
eBook - ePubFrom Atoms to Higgs Bosons
Voyages in Quasi-Spacetime
- Chary Rangacharyulu, Christopher J. A. Polachic, Chary Rangacharyulu, Christopher J. A. Polachic(Authors)
- 2019(Publication Date)
- Jenny Stanford Publishing(Publisher)
At this point, there was an additional problem with the way chemical atoms were conceived: The protons, alone, could not account for the total observed mass of atomic nuclei. A heavy, electrically neutral particle was required to contribute the additional mass while keeping the overall electric charge of atoms neutral. The neutron was discovered in 1932, satisfying this demand.Thus, protons and neutrons are now known to give mass to the nucleus of a chemical atom. Protons fix the rank of an atom in the Mendeleevian periodic table of elements, while electrons guarantee zero overall electric charge and are responsible for all chemical reactions and thus the complex biological phenomena of life. It would be reasonable to think that having identified three basic constituents that suffice for the formation of chemical atoms, we might have found the true physical entities of Democritus’ philosophy. The proton, neutron, and electron certainly appear to be a complete set of particles necessary to build matter and explain the world as it is around us. However, almost immediately, the status of the proton and neutron as “Fundamental Particles” came under scrutiny.7.3 Protons and Neutrons Are Particles, but Are They Fundamental?
Physicists of the twentieth century had several concerns with identifying protons and neutrons as fundamental: the finite size of the nucleons, the instability of free neutrons, and the presence of excitations similar to those seen in composite bodies such as atoms.The first difficulty is a philosophical one: Protons and neutrons are not point objects, which is another way of saying that they appear to have definite size. Indeed, the electromagnetic properties of protons and neutrons do not conform to the theoretical predictions of point-like entities, but it should be said that even in recent years, there has been intense discussion among particle physicists about discrepancies in the size of the proton as measured by different experimental techniques.
eBook - PDF- Nelson Boli´var(Author)
- 2023(Publication Date)
- Arcler Press(Publisher)
What is the lowest possible unit of matter? In other words, what are the basic or elemental components of matter? What forces are at work on such basic particles? Is it feasible to unite such natural forces into a single integrated force that accounts for all observable interactions? In this chapter, we will try to address such questions (Gatti and Manfredi, 1986; Passon et al., 2018). 4.2. PARTICLES AND ANTIPARTICLES Democritus and Leucippus, Greek philosophers, proposed that matter is made up of basic or essential particles known as atoms. The theory gained scientific support when John Dalton published A New System of Chemical Philosophy in 1808, wherein the enumerated around 20 chemical elements, every composed of one atom. There were about 60 known elements in 1896. It became clear that there had to be a mechanism to organize such distinct atoms to make sense of what had been swiftly devolving into chaos. Dimitri Mendeleev, a Russian scientist, produced the periodic table of the elements in 1869, depending on the chemical characteristics of the elements. The turmoil of the great variety of components was kept under control. The periodic table’s unfilled spots have been used to anticipate new chemical elements. The atom might no longer be regarded as elementary when the interior structure of the atom was discovered (Okun, 1998; Plotnitsky, 2021). The proton, electron, photon, and neutron were the only four essential particles recognized in 1932. Things seemed straightforward once more. This ease, however, was not to continue. In cosmic radiation, other particles had been quickly found. Cosmic radiations are cosmic particles that collide with the top of the atmosphere. Certainly, make it to the earth’s surface, Elementary Particle Physics 89 while others decompose into other particles before reaching the surface. Additional new particles had been discovered in man-made big accelerating devices. Hundreds of these particles exist now (Peskin, 2008; Kazakov, 2019).
eBook - PDFRadioisotope and Radiation Physics
An Introduction
- M Miladjenovic(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
CHAPTER 2 MATTER 2 .1. Elementary Particles The properties of matter will be considered in the order of the com-plexity of physical systems. We shall begin with the constituent particles of the atom, and conclude with such complex systems as crystals. The constituent particles of the atom were said to be elementary as long as only a few elementary particles were known in physics. After World War II the list of elementary particles began to rapidly increase, so that, at present, it is established that there are about a hundred such particles. Nowadays the term ''elementary is by definition no longer adequate, but we shall use it, since it will have a definite relative meaning in our discussion. Namely, we shall dwell only on those particles which describe ordinary natural phenomena, including radioactive decay. We shall put aside unstable particles produced by energy expenditure larger than 100 MeV. Examples of such unstable particles are mesons and hyperons, the masses of which amount to more than 200 electron rest masses and lifetimes of which are shorter than 10~ 6 sec. In radioactive decays, amounts of energy less than a few million electron volts are released. Still smaller energies are characteristic of the structure of atoms, molecules, and crystals and of the processes 14 2.2. Antiparticles 15 taking place in these. Hence, radioactive decay and processes induced by radioactive radiation are classed among low-energy phenomena. Low-energy phenomena can be described by means of the following elementary particles: nucleons (protons and neutrons), electrons, neu-trinos, and photons. Atomic nuclei are composed of nucleons, while atomic shells consist of electrons. Changes in the energy of these systems are accompanied by absorption and emission of photons. The neutrino appears in beta decays, where one of the nucleons transforms into the other by emission of an electron and a neutrino.
eBook - PDF- David J. Griffiths(Author)
- 2012(Publication Date)
- Cambridge University Press(Publisher)
4 Elementary particles Elementary particle physics addresses the question, “What is matter made of?” on the most fundamental level – which is to say, on the smallest scale of size. It’s a remarkable fact that matter, at this scale, comes in tiny chunks, sepa- rated by vast empty spaces. This is radically different from our everyday expe- rience, where matter appears to fill everything. Solids seem . . . well . . . solid, liquids are smooth and continuous, and even gases, such as the air in a room, occupy every nook and cranny. But the world of the very small is much more like the night sky, with pinpoints of light here and there, but mostly just nothing. Even more surprising, these “chunks” come in a relatively small number of different types – there are protons and electrons, pi mesons and neutri- nos, . . . only a few dozen in all. Again, this is totally different from our macro- scopic world, where there are rocks and dirt clods, bananas and chimpanzees, trees, books, and people – variety without limit. Most astonishing of all, the chunks of any particular type are not just “pretty similar,” like two Fords coming off the same assembly line, but absolutely utterly identical. There aren’t fat electrons and skinny ones, or young electrons and old electrons, or happy electrons and sad electrons – if you’ve seen one, you’ve seen them all. There is nothing remotely like this absolute identicalness in everyday life – it is a quantum phenomenon, inconceivable in classical physics, where you could always, if necessary, paint a red spot on the object, or stamp a serial number on it. But you can’t paint a spot on an electron, and if you blink, you can’t even be sure that two electrons didn’t change places. This utter indistinguishability underlies the Pauli exclusion principle, without which most of chemistry would be impossible.
- Martinus J G Veltman(Author)
- 2003(Publication Date)
- World Scientific(Publisher)
The way these quarks are bound in a proton or neutron is quite complicated, and not fully under-stood. Statements about the quark content of proton and neutron must be taken with a grain of salt, because in addition there are particles called gluons which cause the binding and which are u u u d d d u d u u d d P N 13 P R E L I M I N A R I E S much more dominantly present than for example photons in an atom (the atomic binding is due to electromagnetic forces, thus photons do the job of binding the electrons to the nucleus). In fact, much of the mass of a proton or a neutron resides in the form of energy of the gluons, while the energy residing in the electric field of an atom is very small. For all we know electrons and quarks are elementary particles, which means that in no experiment has there anything like a structure of these particles been seen. They appear point-like, unlike the proton, neutron, nucleus and atom that have sizes that can be measured. It is of course entirely possible that particles that are called elementary today shall turn out to be composite; let it be said though that they have been probed quite extensively. This book is about elementary particles. The aim is to know all about them, their properties and their interactions. The idea is that from this nuclear physics, atomic physics, chemistry, in fact the whole physical world derives. Thus particles and their interactions are the very fundamentals of nature. That is the view now. An elementary particle physicist studies primarily these elementary particles and not the larger structures such as protons, nuclei or atoms. The main laboratory for elementary particle research in Europe has been named CERN (Conseil Européen pour la Recherche Nucléaire), now officially called European Organization for Nuclear Research and that is a misnomer. In principle no nuclear physics is being done there.
eBook - PDFChemistry of the Non-Metals
With an Introduction to Atomic Structure and Chemical Bonding
- Ralf Steudel, Frederick C. Nachod, Jerry J. Zuckerman, Frederick C. Nachod, Jerry J. Zuckerman(Authors)
- 2011(Publication Date)
- De Gruyter(Publisher)
The numbers of nuclear charges and electrons are equal, insuring elec-tric neutrality. From the α-particle scattering, Rutherford calculated the nuclear charge number which agreed with the atomic number of the respective element in the periodic system proposed in 1869 by D.I. Mendeleev and independently by L. Meyer. The radii of atomic nuclei were calculated to be of the order of 5Ξ10 ~ 12 cm. In comparison with the atomic radius of 10~ 8 cm obtained from kinetic theory, the result indicated that the largest portion of the atomic volume was made up of almost massless electrons. N. Bohr, using Planck's quantum theory calculated the planetary model of the atom exactly for hydrogen, and gave a detailed explanation of its atomic spectrum. 2. Elementary Particles Elementary particles are units which are not further sub-divisible, but which may be transmuted into other elementary particles. At present some hundred elementary particles are known, but only a few are important to the chemist (cf. Table 1). A. Einstein in 1905 formulated the equivalence of mass and energy in his special theory of relativity E = me 2 (1) c = light velocity = 2.998 · 10 8 m/s Thus, a particle may be characterized by its mass or its energy. While physicists prefer energy (electron volts), the chemist is more familiar with classification ac-cording to mass. According to Einstein, however, the mass of a particle is a func-tion of its velocity: m = (2) c = light velocity where m 0 ist the mass at v = 0, or rest mass. As long as v is less than iO% of c, m differs from m 0 by less that 0.5%. Yet for v = 50% c, m = 1.15 m 0 . Forms of energy which like photons or y-quanta have a rest mass of zero are listed among elementary particles. The energy of photons, according to M. Planck (1900), is proportional to their frequency, v: E = hv (3) h = Planck's constant 6.626-10-34 J-s The properties of some elementary particles are summarized in Table 1.
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