Tip 1: How to determine the charge of an atom
Tip 1: How to determine the charge of an atom
Charge atom, along with its quantum numbers, is one of the most important numerical characteristics atom. Knowledge of charge atom it is necessary to solve various problems of electrostatics, electrodynamics, atomic and nuclear physics.
You will need
- Knowledge of the structure of the atom, atomic number
Instructions
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The atom of any substance consists of an electronicshell and core. The core consists of two types of particles - neutrons and protons. Neutrons do not have an electric charge, that is, the electric charge of neutrons is not zero. Protons are positively charged particles and have an electric charge of +1. The number of protons characterizes the atomic number of a given atom..The electronic shell of the nucleus consists of electronic orbitals, on which a different number of electrons are located. Electron is a negatively charged elementary particle. Its electric charge is -1.
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In order to determine the charge atom, it is necessary to know its structure - the number of protons in the nucleus and the number of electrons in the electron shell. Total charge atom is obtained as a result of the algebraicsummation of the charges of the protons and electrons entering into it. As a rule, the atom is electrically neutral, that is, the number of protons in it is equal to the number of electrons. Charge such a atom, is obviously equal to zero. For example, the hydrogen atom H consists of one proton and one electron. Q = 1 + (- 1) = 0 is the charge of electrically neutral hydrogen.
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For some reasons, the number of protons andelectrons in the atom may not coincide. In this case, the atom is a positively or negatively charged ion. For example, a positive sodium ion has 11 protons and 10 electrons. Its charge is Q = 11 + (-10) = 1.
Tip 2: How to determine the nuclear charge
The atom of a chemical element consists of core and an electronic shell. The nucleus is the central part of the atom, in which almost all of its mass is concentrated. Unlike the electron shell, the nucleus has a positive charge.
You will need
- Atomic number of the chemical element, Mosely's law
Instructions
1
The nucleus of an atom consists of two types of particles - protons and neutrons. Neutrons are electrically neutral particles, that is, their electric charge is equal to zero. Protons are positively charged particles and their electric charge is equal to +1.
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In this way, charge core is equal to the number of protons. In turn, the number of protons in the nucleus is equal to the atomic number of the chemical element. For example, the atomic number of hydrogen is 1, that is, the nucleus of hydrogen consists of one proton has charge +1. The atomic number of sodium is 11, charge him core is equal to +11.
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In the case of alpha decay core its atomic number is reduced by two due to the emission of an alpha particle (core helium atom). Thus, the number of protons in a nucleus that has experienced alpha decay also decreases by two. Beta decay can occur in three different forms. In the case of beta-minus decay, the neutron becomes a proton in the emission of an electron and antineutrinos. Then charge core increases by one. In the case of beta-plus decay, the proton is converted into a neutron, a positron and a neutrino, charge core decreases by unity. In the case of electronic capture charge core also decreases by one.
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Charge core can also be determined from the frequency of the spectrallines of characteristic radiation of an atom. According to Mosely's law: sqrt (v / R) = (ZS) / n, where v is the spectral frequency of the characteristic radiation, R is the Rydberg constant, S is the screening constant, n is the principal quantum number. Thus, Z = n * sqrt ( v / r) + s.
Tip 3: How to determine the electrical charge
Electric charge is a quantity,characterizing the ability of a physical body to be the source of an electromagnetic field and to take part in interaction with other similar sources. Even the ancient Greeks discovered that if a piece of amber rubbed against wool, then it will acquire the ability to attract light objects. Amber in the ancient Greek language was called "electron".
Instructions
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To the pupils, who studied physics in the senior classes,for certain is known the elementary device - the electrometer. It consists of a metal rod with a round horizontally arranged protrusion. An arrow is placed on this ledge, which can rotate freely. What happens if a charged body touches the metal rod of the electromagnet? Part of the charge as it flows over the rod and arrow. But since these charges are of the same name, they will repel each other. And the arrow will deviate from the original position by some angle. Using a graduated scale, it is measured and the charge is calculated. It is easy to understand that the higher the charge, the greater the angle of deflection of the arrow of the electrometer, and vice versa. Of course, with the help of such a primitive device it is possible to make only an approximate determination of the magnitude of the charge. If high accuracy is required, sensitive electronic electrometers are used.
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You can use Coulomb's law: F = kq1q2 / r ^ 2, where F is the force of interaction between two charged bodies, q1 and q2 are the values of their charges, r is the distance between the centers of these bodies, and k is the proportionality coefficient. In other words, if you have a body whose charge q1 is known to you, then, by carrying the second body whose charge q2 needs to be determined by the distance r and the interaction force F by the sensitive dynamometer instrument, you easily calculate the required charge q2 by the formula: q2 = Fr ^ 2 / (kq1).
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It is also possible to clean the value of the charge by measuringcurrent in the circuit. The fact is that the total value of the charge flowing through the cross section of a conductor is calculated by the formula: Q = IT, where I is the amperage current, and T is the time in seconds. For this experience, you will need a stopwatch and an ammeter - a device for determining the amperage. Assemble the electrical circuit where the ammeter is turned on, turn on the current, record the ammeter reading. Open the circuit while turning off the stopwatch. Write down how long the current was in the circuit. And by the above formula, calculate the total electrical charge.
