Answer from Ksenia Gareeva[guru]
period number
Answer from Slava mikailov[newbie]
Answer from Bet[guru]
Energy level
Material from Wikipedia - the free encyclopedia
Energy level - possible energy values quantum systems, i.e. systems consisting of microparticles (electrons, protons and other elementary particles, atomic nuclei, atoms, molecules, etc.) and obeying the laws quantum mechanics. Characterizes a certain state of the microparticle. There are electronic and intranuclear energy levels.
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Electronic energy levels
The modern concept of the orbital model of an atom, in which electrons move from one energy level to another, and the difference between the energy levels determines the size of the emitted or absorbed quantum. In this case, electrons cannot be located in the gaps between energy levels. These gaps are called the forbidden energy zone.
An example is an electron in the orbital model of an atom - depending on the values of the principal quantum number n and the orbital quantum number l, the energy level possessed by the electron changes. Accordingly, each pair of values of numbers n and l corresponds to a certain energy level.
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Intranuclear energy levels
The term originated from research into radioactivity. Radiation is divided into three parts: alpha rays, beta rays and gamma rays. Research has shown that alpha radiation consisted of helium atoms, beta radiation is a stream of fast-moving electrons, and research on gamma rays has shown that the energy of electronic levels is not enough to produce them. It became clear that the source of radioactive radiation (gamma rays) must be sought inside the atomic nucleus, that is, there are intranuclear energy levels, the energy of which is converted into gamma radiation photons. Gamma rays have expanded the spectrum of known electromagnetic waves, and all waves shorter than 0.01 nm are gamma rays.
A. 2e, 8e, 8e, 1e B. . 2e, 8e,
18th, 8th, 1st
B. 2e, 1e D. 2e, 8e, 1e
2 (2 points). The number of electrons in the outer electron layer of an aluminum atom:
A. 1 B. 2 C. 3 D.4
3 (2 points). A simple substance with the most pronounced metallic properties:
A. Calcium B. Barium C. Strontium D. Radium
4 (2 points). View chemical bond in a simple substance - aluminum:
A. Ionic B. Covalent polar
B. Metallic D. Covalent nonpolar
5 (2 points). The number of energy levels of elements of one subgroup from top to bottom:
A. Changes periodically. B. Does not change.
B. Increases. D. Decreases.
6 (2 points). A lithium atom differs from a lithium ion:
A. 3-near the nucleus. B. The number of electrons at the external energy level.
B. The number of protons. D. The number of neutrons.
7 (2 points). Reacts least vigorously with water:
A. Barium. B. Magnesium.
B. Calcium. G. Strontium
8 (2 points). Does not interact with sulfuric acid solution:
A. Aluminum. B. Sodium
B. Magnesium. G. Copper
9 (2 points). Potassium hydroxide does not react with a substance whose formula is:
A. Na2O B. AlCl3
B. P2O5 D. Zn(NO3)2
10 (2 points). A series in which all substances react with iron:
A. HCl, CO2, CO
B. CO2, HCl, S
B. H2, O2, CaO
G. O2, CuSO4, H2SO4
11 (9 points). Suggest three ways to obtain sodium hydroxide. Confirm your answer with reaction equations.
12 (6 points). Carry out a chain of chemical transformations by drawing up reaction equations in molecular and ionic forms, name the reaction products:
FeCl2 → Fe(OH)2 → FeSO4 → Fe(OH)2
13 (6 points). How, using any reagents (substances) and zinc, to obtain its oxide, base, salt? Write the reaction equations in molecular form.
14 (4 points). Write an equation chemical reaction interaction of lithium with nitrogen. Identify the reducing agent and oxidizing agent in this reaction
determine by:
A. group number;
B. period number;
B. serial number.
4. Which of the characteristics of chemical elements does not change in the main subgroups:
And the radius of the atom;
B the number of electrons in the outer level;
B. number of energy levels.
5. The structure of the atoms of elements with serial numbers 7 and 15 has something in common:
A. number of electrons in the outer level, B. charge of the nucleus;
B. number of energy levels.
Establish a correspondence between the symbol of a chemical element (in a given order) and the number of electrons in the outer energy level of its atom. From lettersBased on the correct answers, you will create the name of an installation that will allow humanity to understand the structure of the atom even more deeply (9 letters).
Number e on Element Symbol
Energy
level Mg Si I F C Ba Sn Ca Br
2 drops of sem
4 a o v k a t d h i
7 v y l l n g o l r
1 (3 points). Distribution of electrons by energy levels in the sodium atom -A. 2 ē, 1 ē B. 2 ē, 4 ē C. 2 ē, 8 ē, 1 ē. G. 2 ē, 8 ē, 3 ē.
2 (4 points) Period number in Periodic table D.I. Mendeleev, in which there are no chemical elements-metals: A. 1. B. 2. C. 3. D. 4.
3 (3 points). Type of chemical bond in the simple substance calcium:
A. Ionic. B. Covalent polar. B. Covalent nonpolar. G. Metal.
4 (3 points). A simple substance with the most pronounced metallic properties:
A. Aluminum. B. Silicon. B. Magnesium. G. Sodium.
5 (3 points). The radius of atoms of elements of the 2nd period with increasing nuclear charge from an alkali metal to a halogen: A. Changes periodically. B. Does not change. B. Increases. D. Decreases.
6 (3 points). A magnesium atom differs from a magnesium ion:
A. Nuclear charge. B. Charge of the particle. B. The number of protons. D. The number of neutrons.
7 (3 points). Reacts most vigorously with water:
A. Potassium. B. Lithium. B. Sodium. G. Rubidium.
8 (3 points). Does not react with dilute sulfuric acid:
A. Aluminum. B. Barium. B. Iron. G. Mercury.
9 (3 points). Beryllium hydroxide does not react with a substance whose formula is:
A. NaOH(p p). B. NaCl(p_p). B. NS1(r_r). G. H2SO4.
10 (3 points). A series in which all substances react with calcium:
A. CO2, H2, HC1. B. NaOH, H2O, HC1. B. C12, H2O, H2SO4. G. S, H2SO4, SO3.
PART B. Free-response questions
11 (9 points). Suggest three ways to obtain iron (II) sulfate. Confirm your answer with reaction equations.
12 (6 points). Identify substances X, Y, Z, write down their chemical formulas.
Fe(OH)3(t)= X(+HCl)= Y(+NaOH)=Z(t) Fe2O3
13 (6 points). How, using any reagents (substances) and aluminum, to obtain an oxide, amphoteric hydroxide? Write the reaction equations in molecular form.
14 (4 points). Arrange the metals: copper, gold, aluminum, lead in order of increasing density.
15 (5 points). Calculate the mass of the metal obtained from 160 g of copper (II) oxide.
– particles that form molecules.Try to imagine how small atoms are compared to the size of the molecules themselves using this example.
Let's fill the rubber ball with gas. If we assume that a million molecules per second will exit the ball through a thin puncture, then it will take 30 billion years for all the molecules to escape from the ball. But one molecule can contain two, three, or maybe several tens or even several thousand atoms!
Modern technology has made it possible to photograph both the molecule and the atom using a special microscope. The molecule was photographed at a magnification of 70 million times, and the atom at a magnification of 260 million times.
For a long time, scientists believed that the atom was indivisible. Even a word atom translated from Greek means "indivisible". However, many years of research have shown that, despite their small sizes, atoms consist of even smaller parts ( elementary particles).
Isn't it true that the structure of an atom resembles solar system ?
IN center of the atom – a nucleus around which electrons move at a certain distance
Core- the heaviest part of the atom, the mass of the atom is concentrated in it.
The nucleus and electrons have electric charges, opposite in sign, but equal in magnitude.
The nucleus has a positive charge, the electrons have a negative charge, so the atom as a whole is not charged.
Remember
All atoms have a nucleus and electrons. Atoms differ from each other: in the mass and charge of the nucleus; number of electrons.
Exercise
Count the number of electrons in the atoms of aluminum, carbon, and hydrogen. Fill out the table.
|
· Atom name |
Number of electrons in an atom |
|
Aluminum atom |
|
|
carbon atom |
|
|
Hydrogen atom |
Do you want to know more about the structure of the atom? Then read on.
The charge of the nucleus of an atom is determined by the atomic number of the element.
For example , the atomic number of hydrogen is 1 (determined from the Periodic Table of Mendeleev), which means that the charge of the atomic nucleus is +1.
The atomic number of silicon is 14 (determined from the Periodic Table of Mendeleev), which means that the charge of the nucleus of a silicon atom is +14.
For an atom to be electrically neutral, the number of positive and negative charges in the atom must be equal
(the total will be zero).
The number of electrons (negatively charged particles) is equal to the charge of the nucleus (positively charged particles) and is equal to the atomic number of the element.
A hydrogen atom has 1 electron, a silicon atom has 14 electrons.
Electrons in an atom move through energy levels.
The number of energy levels in an atom is determined by the period number, in which the element is located (also determined from the Periodic Table of Mendeleev)
For example, hydrogen is an element of the first period, which means it has
1 energy level, and silicon is a third period element, therefore 14 electrons are distributed over three energy levels. Oxygen and carbon are third-period elements, so electrons move through three energy levels.
Exercise
1.What is the nuclear charge in the atoms of the chemical elements shown in the figure?
2. How many energy levels are there in an aluminum atom?
2. Structure of nuclei and electron shells of atoms
2.6. Energy levels and sublevels
The most important characteristic of the state of an electron in an atom is the energy of the electron, which, according to the laws of quantum mechanics, does not change continuously, but abruptly, i.e. can only take very specific values. Thus, we can talk about the presence of a set of energy levels in an atom.
Energy level- a set of AOs with similar energy values.
Energy levels are numbered using principal quantum number n, which can only take positive integer values (n = 1, 2, 3, ...). The larger the value of n, the higher the energy of the electron and that energy level. Each atom contains an infinite number of energy levels, some of which are populated by electrons in the ground state of the atom, and some are not (these energy levels are populated in the excited state of the atom).
Electronic layer- a set of electrons located at a given energy level.
In other words, the electron layer is an energy level containing electrons.
The combination of electronic layers forms the electron shell of an atom.
Within the same electron layer, electrons can differ slightly in energy, and therefore they say that energy levels are split into energy sublevels(sublayers). The number of sublevels into which a given energy level is split is equal to the number of the main quantum number of the energy level:
N (subur) = n (level) . (2.4)
Sublevels are depicted using numbers and letters: the number corresponds to the number of the energy level (electronic layer), the letter corresponds to the nature of the AO that forms the sublevels (s -, p -, d -, f -), for example: 2p -sublevel (2p -AO, 2p -electron).
Thus, the first energy level (Fig. 2.5) consists of one sublevel (1s), the second - of two (2s and 2p), the third - of three (3s, 3p and 3d), the fourth of four (4s, 4p, 4d and 4f) etc. Each sublevel contains a certain number of joint stock companies:
N(AO) = n2. (2.5)
Rice. 2.5.
1. s-type AOs are present at all energy levels, p-types appear starting from the second energy level, d-type - from the third, f-type - from the fourth, etc.
2. At a given energy level there can be one s-, three p-, five d-, seven f-orbitals.
3. The larger the principal quantum number, the larger the size of the JSC.
Since one AO cannot contain more than two electrons, the total (maximum) number of electrons at a given energy level is 2 times greater than the number of AOs and is equal to:
N (e) = 2n 2 . (2.6)
Thus, at a given energy level there can be a maximum of 2 s-type electrons, 6 p-type electrons and 10 d-type electrons. In total, at the first energy level the maximum number of electrons is 2, at the second - 8 (2 s-type and 6 p-type), at the third - 18 (2 s-type, 6 p-type and 10 d-type). It is convenient to summarize these conclusions in table. 2.2.
Table 2.2
The connection between the principal quantum number, the number e
Today we will talk about what the energy level of an atom is, when a person encounters this concept, and where it is applied.
School physics
People meet for the first time natural sciences At school. And if in the seventh year of study children still find new knowledge in biology and chemistry interesting, then in high school they begin to be afraid of them. When the turn of atomic physics comes, lessons in this discipline already inspire only disgust for incomprehensible tasks. However, it is worth remembering that all discoveries that have now turned into boring school items, a non-trivial history and a whole arsenal of useful applications. Finding out how the world works is like opening a box with something interesting inside: you always want to find the secret compartment and discover another treasure there. Today we will talk about one of the basic physics, the structure of matter.
Indivisible, composite, quantum
From the ancient Greek language the word “atom” is translated as “indivisible, smallest.” This idea is a consequence of the history of science. Some ancient Greeks and Indians believed that everything in the world was made up of tiny particles.
In modern history were produced much earlier physical research. Scholars of the seventeenth and eighteenth centuries worked primarily to increase the military power of the country, king, or duke. And in order to create explosives and gunpowder, it was necessary to understand what they consist of. As a result, the researchers found that some elements cannot be separated beyond a certain level. This means that there are the smallest carriers of chemical properties.
But they were wrong. The atom turned out to be a composite particle, and its ability to change is quantum in nature. This is also evidenced by transitions in the energy levels of the atom.
Positive and negative
At the end of the nineteenth century, scientists came close to studying the smallest particles of matter. For example, it was clear: an atom contains both positively and negatively charged components. But it was unknown: the location, interaction, and weight ratio of its elements remained a mystery.
Rutherford conducted an experiment on the scattering of thin alpha particles. He found out that in the center of the atoms there are heavy positive elements, and at the edges there are very light negative ones. This means that the carriers of different charges are particles that are not similar to each other. This explained the charge of atoms: an element could be added to them or one could be removed. The equilibrium that maintained the neutrality of the entire system was disrupted, and the atom acquired a charge.
Electrons, protons, neutrons
Later it turned out that light negative particles are electrons, and a heavy positive nucleus consists of two types of nucleons (protons and neutrons). Protons differed from neutrons only in that the former were positively charged and heavy, while the latter only had mass. Changing the composition and charge of the nucleus is difficult: it requires incredible energy. But an atom is divided much more easily by an electron. There are more electronegative atoms that are more willing to “take away” an electron, and less electronegative atoms that are more likely to “give” it up. This is how the charge of an atom is formed: if there is an excess of electrons, then it is negative, and if there is a deficiency, then it is positive.
Long life of the universe
But this atomic structure puzzled scientists. According to the prevailing classical physics of those times, an electron, which was constantly moving around the nucleus, should have continuously emitted electromagnetic waves. Since this process means a loss of energy, all negative particles would soon lose their speed and fall onto the core. However, the universe has existed for a very long time, and a worldwide catastrophe has not yet occurred. The paradox of matter being too old was brewing.
Bohr's postulates
Bohr's postulates were able to explain the discrepancy. Then these were simply statements, leaps into the unknown, which were not supported by calculations or theory. According to the postulates, there were energy levels of electrons in the atom. Each negatively charged particle could only be at these levels. The transition between orbitals (as the levels are called) is carried out by a jump, in which a quantum of electromagnetic energy is released or absorbed.
Planck's discovery of the quantum later explained this behavior of electrons.
Light and atom
The amount of energy required for the transition depends on the distance between the energy levels of the atom. The farther they are from each other, the greater the emitted or absorbed quantum.
As you know, light is a quantum electromagnetic field. Thus, when an electron in an atom moves from a higher to a lower level, it creates light. In this case, the opposite law also applies: when an electromagnetic wave falls on an object, it excites its electrons, and they move to a higher orbital.
In addition, the energy levels of the atom are individual for each type chemical element. The pattern of distances between orbitals differs for hydrogen and gold, tungsten and copper, bromine and sulfur. Therefore, analysis of the emission spectra of any object (including stars) unambiguously determines what substances are present in it and in what quantity.
This method is used incredibly widely. Spectral analysis used:
- in criminology;
- in food and water quality control;
- in the production of goods;
- in the creation of new materials;
- in improving technology;
- in scientific experiments;
- in the study of stars.
This list only roughly shows how useful the discovery of electronic levels in the atom turned out to be. Electronic levels are the roughest, the largest. There are finer vibrational and even finer rotational levels. But they are relevant only for complex compounds - molecules and solids.
It must be said that the structure of the nucleus has not yet been fully studied. For example, there is no answer to the question of why a certain number of protons corresponds to exactly that number of neutrons. Scientists suggest that atomic nucleus also contains some analogue of electronic levels. However, this has not yet been proven.
