Properties of subatomic particles

The development of particle accelerators grew out of the discovery of radioactivity in uranium by Henri Becquerel in Paris in 1896. Some years later, due to the work of Ernest Rutherford and others, it was found that the radioactivity discovered by Becquerel was the emission o particles with kinetic energies o several MeV from uranium nuclei. Research using the emitted particles began shortly thereafter. It was soon realized that if scientists were to learn more about the properties of subatomic particles, they had to be accelerated to energies greater than those attained in natural radioactivity. 

The de Broglie equation predicts that eveiy particle has wave characteristics. The wave properties of subatomic particles such as electrons and neutrons play important roles in their behavior, but larger particles such as Ping-Pong balls or automobiles do not behave like waves. The reason is the scale of the waves. For all except subatomic particles, the wavelengths involved are so short that we are unable to detect the wave properties. Example illustrates this. 

Quarks carry a fractional charge of Vj or Fy Six flavors or types of quarks make up all subatomic particles. Each flavor of quark can be fiufher classified as having one of three colors. These are not colors or flavors as commonly thought of, but part of a classification scheme used to explain how matter behaves. The language of quarks makes them seem like some creation of fantasy, but the quark theory can be used to explain many properties of subatomic particles. For example, a proton can be considered to be made of two up quarks and a down quark, and a neutron of two down quarks and an up quark (Figure 4.8). Quark flavors and charges are given in Table 4.5. 

To use the properties of subatomic particles— protons, electrons, and neutrons—to determine atomic structure... 

This is the conservative or orthodox view of the mind discussed briefly at the beginning of this book. It does not really explain what consciousness is, but, citing good evidence that physically affecting the brain alters consciousness, asks not further questions and simply believes that consciousness itself is a product of brain functioning. The consequence of this view is that for an ultimate explanation of consciousness, the phenomena of consciousness must be reduced to those of brain functioning brain functioning must be reduced to basic properties of nervous systems, which must be reduced to basic properties of live molecules, which in turn must be reduced to basic properties of molecules per se, which must be reduced to properties of atoms, which must finally be reduced to properties of subatomic particles. 

For over 200 years, scientists have known that all matter consists of atoms, and they have learned astonishing things about them. Dalton s tiny indivisible particles have given way to atoms with fuzzy, indistinct boundaries and an elaborate internal architecture of subatomic particles. In this section, we examine our current model and begin to see how the properties of subatomic particles affect the properties of atoms. 

The Large Hadron Collider at CERN studies the properties of subatomic particles and nuclear matter. 

Table 4.3 Properties of Subatomic Particles Interactive Table Explore the properties of subatomic particles at qlencoe.com. ...

Copy and complete the following table concerning the properties of subatomic particles. 

Determine the arrangement and structure of subatomic particles in atoms. Protons, neutrons, and electrons play a central role in everything chemistry, and you find their most basic properties in this part. 

STRUCTURE, THE PRINCIPLES OF QUANTUM THEORY, AND THE PROPERTIES AND INTERACTIONS OF SUBATOMIC PARTICLES. 

A better understanding of the structure of the atom came about through additional experiments in the early 1900s. The discovery of the subatomic particles was a major breakthrough in atomic structure. These particles were classified as electrons and nucleons. The nucleons were later found to be neutrons and protons. The properties of these particles can be compared side by side ... 

The atom is composed of many types of subatomic particles, but only three types will be important in this course. Protons and neutrons exist in the atom s nucleus, and electrons exist outside the nucleus. The nucleus (plural, nuclei) is incredibly small, with a radius about one ten-thousandth of the radius of the atom itself. (If the atom were the size of a car, the nucleus would be about the size of the period at the end of this sentence.) The nucleus does not change during any ordinary chemical reaction. (Nuclear reactions are described in Chapter 21.) The protons, neutrons, and electrons have the properties listed in Table 3.1. These properties are independent of the atom of which the subatomic particles are a part. Thus, the atom is the smallest unit that has the characteristic composition of an element, and in that sense, it is the smallest particle of an element. 

Atom The smallest particle of matter that maintains the property of an element in the periodic table atoms are composed of subatomic particles called electrons, neutrons, and protons, which themselves are composed of even tinier subatomic particles such as quarks. 

Apart from use of experimental values of atomic - rather than nuclear - and electronic masses and of electric charges, the basis of this calculation has an empirical component. The calculation is certainly not made genuinely from first principles or ab initio, firstly because the composition of the basis set is predetermined, by those who have published this basis set [12] and by the authors of Dalton software [11] who have incorporated it, according to its success in reproducing experimentally observable quantities and other calculated properties. Secondly, the solution of Schrodinger s equation is based on a separation of electronic and nuclear motions, essentially with atomic nuclei fixed at relative positions, which is a further empirical imposition on the calculation efforts elsewhere to avoid such an arbitrarily distinct treatment of subatomic particles, even on much simpler molecular systems, have... 

Dalton pictured atoms as featureless spheres, like billiard balls. Today, we know that atoms have an internal structure they are built from even smaller subatomic particles. In this book, we deal with the three major subatomic particles the electron, the proton, and the neutron. By investigating the internal structure of atoms, we can come to see how one element differs from another and see how their properties are related to the structures of their atoms. 

Since Rutherford s work, scientists have identified other types of nuclear radiation. Some consist of rapidly moving particles, such as neutrons or protons. Others consist of rapidly moving antiparticles, particles with a mass equal to that of one of the subatomic particles but with an opposite charge. For example, the positron has the same mass as an electron but a positive charge it is denoted 3 or f e. When an antiparticle encounters its corresponding particle, both particles are annihilated and completely converted into energy. Table 17.1 summarizes the properties of particles commonly found in nuclear radiation. 

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