Molecules are built from atoms. A molecule is the smallest particle of a substance that determines its properties and is capable of independent existence. Molecules are built from atoms What is the name of the smallest unit that determines its properties
SectionI.
Basic concepts and laws of chemistry
Chapter 1. Atomic-molecular doctrine and stoichiometry
1.1. Basic concepts and definitions
Chemistry part of natural science that studies composition. structure and Chemical properties substances and their transformations, accompanied by a change in composition.
It should be borne in mind that chemistry studies low-energy excesses, the maximum temperature of which does not exceed several thousand degrees, the pressure is up to 100 MPa. These transformations of substances are called chemical reactions.
Under chemical properties substances understand the totality of chemical reactions in which they can enter. As well as physical properties(color, density, hardness, electrical conductivity, melting and boiling points), they are determined by the structure and composition of the substance.
Simple chemical(simple substance) is a substance that consists of atoms of the same chemical element.
Atom the smallest particle of a simple substance that retains all its basic chemical properties. An atom consists of a certain number of protons and neutrons that make up the nucleus, and electrons, the number of which is equal to the number of protons, that is, the atom is electrically neutral. Under the conditions of chemical reactions, an atom cannot be converted into other atoms.
Element the kind of atoms characterized by the same number of protons. An element is assigned an atomic number equal to the number of protons in its nucleus, and it is given a name, the first letters (of the Latin name) of which are the symbol of the element and, in addition, designate one atom and one mole of this element. For example, the element with atomic number 18 is called Argon (Argon lat.) And is denoted Ar; this sign (symbol) of this element denotes the presence of one atom or one mole of atoms (see below). The atomic number of a chemical element is equal to its ordinal number in the Periodic Table chemical elements DI. Mendeleev.
A complex chemical(chemical compound) is a substance consisting of atoms of several elements. Many chemical compounds are made up of molecules, but there are also many compounds with a non-molecular structure.
Molecule called the smallest particle of a substance capable of independent existence and possessing all its chemical properties. For example, molecules consist of hydrogen chloride HCl (1 hydrogen atom is connected to 1 chlorine atom), ammonia NH 3 (1 nitrogen atom is connected to 3 hydrogen atoms), water H 2 O (1 oxygen atom is connected to 2 oxygen atoms), etc. ...
At the same time, in many (usually crystalline) chemical compounds, molecules cannot be distinguished, since they consist of atoms or ions firmly connected to each other, into which it is impossible to separate a complex substance without significantly changing its properties. In this case, the composition of the substance is expressed formula unit. For example, the formula unit K 2 SO 4 denotes a crystalline substance potassium sulfate, in which for every 2 potassium atoms there are 1 sulfur and 4 oxygen atoms.
When describing the composition and structure of a substance, the concept of structural unit (CE) - it's over general concept, denoting any atoms or their groups (including molecules and formula units) that are used to describe the composition of a substance.
Thus, the composition of a substance is expressed by its chemical formula, which determines the ratio between the number of atoms of elements in a compound or the number of atoms in a simple substance. A chemical formula expresses the composition of a molecule if a substance has a molecular structure, or is only a formula unit of a substance if the molecules of a given substance do not exist.
Molecular structure of a substance. Velocities of gas molecules.
The molecular-kinetic theory of MKT is a theory that explains the properties of a substance based on its molecular structure. The main provisions of the molecular kinetic theory: all bodies are composed of molecules; molecules are constantly moving; molecules interact with each other.
Molecule- the smallest particle of a substance that retains the properties of a given substance.
Atoms- the smallest particle of a chemical element. Molecules are made of atoms.
Molecules are constantly moving... The proof of this position is diffusion- the phenomenon of the penetration of molecules of one substance into another. Diffusion occurs in gases and liquids, and in solids... With increasing temperature, the diffusion rate increases. The movement of paint particles in solution discovered by Brown is called Brownian motion and also proves the movement of molecules.
Atom structure... An atom consists of a positively charged nucleus around which electrons revolve.
Atom nucleus consists of nucleons (proton, neutron). The charge of a nucleus is determined by the number of protons. The mass number is determined by the number of nucleons. Isotopes are atoms of the same elements, the nuclei of which contain different amounts of neutrons.
Relative atomic mass M is the mass of one atom in units atomic mass (1/12 of the mass of a carbon atom). Relative molecular weight- M is the mass of the molecule in units of atomic mass.
Amount of substance is determined by the number of molecules. A mole is a unit of measure for the amount of a substance. Moth- the amount of a substance, the mass of which, expressed in grams, is numerically equal to the relative molecular weight. 1 mole substance contains NA molecules. N BUT = 6,022∙10 23 1 / mol - Avogadro number. The mass of one mole in kilograms is called molar mass. – μ = M 10 -3 ... 1 mol - 12gC – N BUT –22.4 liters. gas.
Number moles defined by formulas : ν = m / μ , ν = N / N A , ν = V / V 0 .
Basic MKT model- a set of moving and interacting molecules of a substance. Aggregate states of matter.
Solid: W P >> W k, the packing is dense, the molecules vibrate about the equilibrium position, the equilibrium positions are stationary, the arrangement of molecules is ordered, i.e. a crystal lattice is formed, both shape and volume are preserved.
Liquid:W P ≈ W k , the packing is dense, the molecules vibrate about the equilibrium position, the equilibrium positions are mobile, the arrangement of molecules is ordered within 2, 3 layers (short-range order), the volume is preserved, but the shape is not preserved (fluidity).
Gas: W P W k , molecules are located far from each other, move rectilinearly until they collide with each other, collisions are elastic, and easily change shape and volume. Ideal gas conditions: W P =0, collisions are absolutely elastic, Molecule diameter the distance between them.
Plasma - electrically neutral set of neutral and charged particles ... Plasma(gas) molecules are located far from each other, move rectilinearly before colliding with each other, easily change shape and volume, collisions are inelastic, during collisions ionization occurs, reacts to electric and magnetic fields.
Phase transitions: vaporization, condensation, sublimation, melting, crystallization.
Statistical patterns- laws of behavior of a large number of particles. Microparameters- parameters of small scales - mass, size, velocity and other characteristics of molecules, atoms. Macroparameters - parameters of large scales - mass, volume, pressure, temperature of physical bodies.
R
Z = 2 N
Distribution of ideal gas particles over two halves of the vessel:
Number of possible statesZwith the number of particlesN is found by the formula
H
Z = N! / n! ∙ (N-n)!
A number of ways to implement a staten/ (N – n) is found by the formula
Analysis of the answers leads to the conclusion that the most likely that the molecules will be distributed equally across the two halves of the vessels.
The most likely speed is the speed that most molecules have
How to calculate the average velocity of molecules V cf = (V 1 ∙ N 1 + V 2 ∙ N 2 + V 3 ∙ N 3) / N. The average speed is usually higher than the most probable.
Connection: speed - energy - temperature. E cf ~ T.
T
E = 3 kT / 2
temperature determines the degree of body heat. Temperature main characteristic bodies in thermal equilibrium. Thermal equilibrium when there is no heat transfer between bodies
Temperature is a measure of the average kinetic energy of gas molecules. With an increase in temperature, the diffusion rate increases, and the speed of Brownian motion increases. The formula for the relationship between the average kinetic energy of molecules and temperature is expressed by the formula gdk k = 1.38 ∙ 10 -23 J / K - Boltzmann's constant, expressing the ratio between Kelvin and Joule as units of temperature measurement.
T
T = t + 273.
thermodynamic temperature cannot be negative.
Absolute temperature scale- Kelvin scale (273K - 373K).
Temperature scales: Celsius (0 o C - 100 o C), Fahrenheit (32 o F - 212 o F), Kelvin (273K - 373K).
Thermal movement rate of molecules: m 0 v 2 = 3 kT, v 2 = 3 kT / m 0 , v 2 = 3 kN A T / μ
Gas laws
Pressure is a macroscopic parameter of the system ... The pressure is numerically equal to the force acting on a unit surface perpendicular to this surface.P= F/ S. The pressure is measured in Pascals (Pa), atmospheres (atm.), Bar (bar), mm Hg. The pressure of a column of gas or liquid in a gravitational field is found by the formula P = ρgh, where ρ is the density of the gas or liquid, h is the height of the column. In communicating vessels, a homogeneous liquid is established at the same level. The ratio of the heights of the columns of inhomogeneous fluids is inverse to the ratio of their densities.
Atmosphere pressure- the pressure created by the Earth's air shell. Normal atmospheric pressure is 760 mm Hg. or 1.01 ∙ 10 5 Pa, or 1 bar, or 1 atm.
Gas pressure is determined the number of molecules hitting the vessel wall and their speed.
Average arithmetic speed the movement of gas molecules is equal to zero, because there is no advantage of movement in any particular direction due to the fact that the movement of molecules is equally probable in all directions. Therefore, to characterize the movement of molecules, we take root mean square velocity... Mean squares of speed over X, Y, Z axes are equal to each other and make up 1/3 of the mean square velocity.
For one mole of gas
Isobars
R 1
Gay-Lussac's law,
V = const - isochoric process,
Isohores
V 1
Charles's law.
Tasks: A task № 1 . Determine the total number of microstates of six ideal gas particles from two halves of a vessel not separated by a partition. What is the number of ways to realize the states 1/5, 2/4? Under what state will the number of implementation methods be the maximum?
Decision. Z = 2 N = 2 6 = 64. For the state 1/5 Z = N! / n! ∙ (N-n)! = 1 ∙ 2 ∙ 3 ∙ 4 ∙ 5 ∙ 6/1 ∙ 1 ∙ 2 ∙ 3 ∙ 4 ∙ 5 = 6
On my own... What is the number of ways to realize 2/4 states?
Problem number 2. Find the number of molecules in a glass of water (m = 200g). Decision. N = m ∙ N A / μ = 0.2 ∙ 6.022 ∙ 10 23/18 ∙ 10 -3 = 67 ∙ 10 23.
On your own. Find the number of molecules in 2 g of copper. Find the Number of Molecules in 1m 3 of Carbon Dioxide CO 2 .
Problem number 3. The figure shows a closed loop in coordinates P V... What processes took place with the gas? How did the macroparameters change? Draw this diagram in VT coordinates.
FROM 
independently draw a diagram in PT coordinates.
|
P |
V |
T |
|
|
1-2 |
uv |
fast |
uv |
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2-3 |
fast |
uv |
uv |
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3-4 |
mind |
uv |
fast |
|
4-1 |
fast |
mind |
mind |
solution.
Problem number 4. The Magdeburg Hemispheres stretched 8 horses on each side. How will the pulling force change if one hemisphere is attached to a wall and the other is pulled by 16 horses?
Z problem number 5. An ideal gas exerts a pressure of 1.01 ∙ 10 5 Pa on the walls of the vessel. Thermal velocity of molecules is 500 m / s. Find the density of the gas. (1.21kg / m 3). Decision.... Let us divide both sides of the equation by V. We get
μ we find from the formula for the speed of molecules
Problem number 6. Under what pressure is oxygen if the thermal velocity of its molecules is 550 m / s, and their concentration is 10 25 m -3 ? (54kPa.) Decision. P = nkT, R = N A k,P = n v 2 μ / 3 N A , We find T from the formula
Problem number 7. Nitrogen occupies a volume of 1 liter at normal atmospheric pressure. Determine the energy of translational motion of gas molecules.
Decision. The energy of one molecule is E o = 5 kT / 2 , the energy of all molecules in given volume gas – E = N 5 kT / 2 = nV 5 kT / 2, P = nkT , E = 5 PV / 2 = 250 J.
A task № 8. Air is made up of a mixture of nitrogen, oxygen and argon. Their concentrations are respectively equal to 7.8 ∙ 10 24 m -3, 2.1 ∙ 10 24 m -3, 10 23 m -3. Average kinetic energy the molecules of the mixture are the same and equal to 3 ∙ 10 -21 J. Find the air pressure. (20kPa). On your own.
Problem number 9. How will the gas pressure change with a 4-fold decrease in its volume and a 1.5-fold increase in temperature? (Will increase 6 times). On your own.
Problem number 10. The gas pressure in the fluorescent lamp is 10 3 Pa, and its temperature is 42 o C. Determine the concentration of atoms in the lamp. Estimate the average distance between molecules.
(2.3 ∙ 10 23 m -3, 16.3 nm). On your own.
Problem number 11. Find the volume of one mole of an ideal gas of any chemical composition under normal conditions. (22.4 L). On your own.
Z admission number 12... A 4L vessel contains molecular hydrogen and helium. Assuming the gases are ideal, find the pressure of the gases in the vessel at a temperature of 20 ° C if their masses are 2g and 4g, respectively. (1226kPa).
Decision... By Dalton's Law P = P 1 + P 2 ... We find the partial pressure of each gas by the formula. Both hydrogen and helium occupy the entire volume V = 4 liters.
Problem number 13... Determine the depth of the lake if the volume of the air bubble doubles as it rises from the bottom to the surface. The bubble temperature does not have time to change. (10.3m).
Decision... Isothermal process P 1 V 1 = P 2 V 2
The pressure in the bubble on the water surface is equal to atmospheric Р 2 = Р о The pressure at the bottom of the reservoir is the sum of the pressure inside the bubble and the pressure of the water column R 1 = P about + ρ gh, where ρ = 1000kg / m 3 is the density of water, h is the depth of the reservoir. R about = (R about + ρ gh) V 1 / 2 V 1 = (R about + ρ gh)/ 2
Problem number 14... The cylinder is divided by an impenetrable fixed partition into two parts, the volumes of which are V 1, V 2. The air pressure in these parts of the cylinder is P 1, P 2, respectively. When the fastener is removed, the baffle can move like a weightless piston. How much and in which direction will the partition move?
R
P 1 V 1
P 2 V 2
solution ... If a P 2> P 1 Pressure in both parts
P 1 V 1 = P (V 1 -∆ V)
P 2 V 2 = P (V 2 + ∆ V)
the cylinder will be the same - P. The process is isothermal.
Let's divide the right and left sides of the equations into each other. And then we solve the equation for ∆ V.
Answer: ((P 1 – P 2 ) V 1 V 2 )/(P 1 V 1 + P 2 V 2 .
Problem number 15... Car tires are inflated to a pressure of 2 ∙ 10 4 Pa at a temperature of 7 ° C. A few hours after driving, the air temperature in the tires has risen to 42 ° C. What is the pressure in the tires? (2.25 ∙ 10 4 Pa). On your own.
A substance (for example, sugar) can be ground in the finest mill and still each grain will consist of a huge number of identical sugar molecules and will retain all the properties of this substance known to us. Even if you crush a substance into separate molecules, as happens when sugar is dissolved in water, then the substance continues to exist and show its properties (you can easily verify this by tasting the solution). This means that an independently existing sugar molecule is also a substance called "sugar" (even if a very small amount of this substance). But if you continue crushing further, you will have to destroy the molecules. And by destroying the molecules or even taking away a couple of atoms from them (out of three dozen that make up a sugar molecule!), We are already destroying the substance itself. Of course, atoms do not disappear anywhere - they begin to be part of some other molecules. But sugar as a substance at the same time ceases to exist - it turns into some other substance.
Substances are not eternal, because their molecules are not eternal. But atoms are practically eternal. In each of us there are atoms that have existed since the days of the dinosaurs. Or those who participated in the campaigns of Alexander the Great, or in the voyage of Columbus, or who visited the court of Ivan the Terrible.
Despite the fact that the molecules are very small, their structure can be determined by various physical and chemical methods. A pure substance consists of molecules of the same type. If the physical body contains molecules of several types, then we are dealing with a mixture of substances. The concepts of "pure" in chemistry and in everyday life are not the same. For example, when we say: - "What clean air!" - then we actually inhale a complex mixture of several gases different substances... A chemist will say about forest air: "It is necessary to work seriously to isolate pure substances from this mixture." It is interesting that in the atmosphere of any of them separately, a person could not exist. Table 1-1 shows the ratio of these gaseous substances in fresh forest air.
Table 1-1. Composition of atmospheric air in a pine forest.
Table 1-1 shows nitrogen, oxygen, argon, etc. are separate substances. The substance nitrogen consists of molecules nitrogen, the well-known substance water - from molecules water, terpineol consists of molecules terpineol. The molecules of these substances can be very different - from the simplest, consisting of two or three atoms (nitrogen, oxygen, ozone, carbon dioxide) - to molecules consisting of many atoms (such molecules are found in living organisms). For example, terpineol, which is formed in conifers and gives the air a fresh smell.
This means that there can be an infinite number of substances, as well as types of molecules. No one can name the exact number of substances known to people today. We can only roughly say that there are more than seven million such substances.
The atoms in the molecules of different substances are connected with each other in a strictly defined order, the establishment of which is one of the most interesting things in the work of a chemist. The structure and composition of molecules can be described in different ways, for example, as is done in Fig. 1-1, where the atoms are in the form of balls. The sizes of the balls have a physical meaning and roughly correspond to the relative sizes of the atoms. The same substances can be depicted in a different way - with the help of chemical symbols. For a long time, a symbol of Latin letters has been assigned to each type of atom in chemistry. Table 1-2 shows the symbolic records of the substances shown in Fig. 1-1. Such symbolic records are called chemical formulas.
Table 1-2. Chemical formulas substances from Fig. 1-1. The number below the symbol shows how many atoms of a given type are contained in the molecule. This figure is called the index. Traditionally, the index "1" is never written. For example, instead of C 1 O 2, they simply write: CO 2.
Fig. 1-1. Models of molecules and names of substances that make up the forest air: 1 - nitrogen, 2 - oxygen, 3 - argon, 4 - carbon dioxide, 5 - water, 6 - ozone (formed from oxygen during lightning discharges), 7 - terpineol (released conifers).
There is a conditional division of substances into simple and complex ones. Molecules of simple substances are composed of atoms of the same kind. Examples: nitrogen, oxygen, argon, ozone. Molecules of complex substances are composed of atoms of two or more types: carbon dioxide, water, terpineol.
The physical body is often made up of molecules of several different substances. Such a physical body is called a mixture. For example, air is a mixture of several simple and complex substances. A complex substance should not be confused with a mixture. A complex substance, if it consists of only one type of molecules, is not a mixture.
S, g. molecule f. The smallest particle of a substance, possessing all its chemical properties, capable of existing independently. ALS 1. Molecule. Veselitsky 26. Molecule and Molecule. Michelson 1865. Molecule. This is the name of the endless ... ... Historical Dictionary gallicisms of the Russian language
- (novolat.molecule, abbreviated from lat.moles mass), the smallest number in va, possessing its basic. chem. you and consisting of atoms connected by chemical bonds. The number of atoms in M. ranges from two (H2, O2, HF, KCl) to hundreds and thousands ... Physical encyclopedia
- (diminutive form from Latin moles - mass) the smallest particle of a chemical compound; consists of a system of atoms, with the help of chemical means it can disintegrate into individual atoms. The molecules of noble gases, helium, etc., are monoatomic; the most difficult ... Philosophical Encyclopedia
Excimer, genoneme, episome, chromosome, microparticle, macromolecule Dictionary of Russian synonyms. molecule n., number of synonyms: 10 biomolecule (1) ... Synonym dictionary
MOLECULE, the smallest particle of a substance that has its basic chemical properties. Consists of atoms arranged in space in a certain order and connected by chemical bonds. The composition and arrangement of atoms are reflected in the chemical ... ... Modern encyclopedia
- (Novolat molecula will reduce from Latin moles mass), a microparticle formed from atoms and capable of independent existence. It has a constant composition of its constituent atomic nuclei and a fixed number of electrons and has a set of ... ... Big Encyclopedic Dictionary
MOLECULE, molecules, wives. (from Lat.moles mass) (eating). The smallest particle of a substance that can exist independently and has all the properties of a given substance. Molecules are made up of atoms. Dictionary Ushakov. D.N. Ushakov. 1935 1940 ... Ushakov's Explanatory Dictionary
MOLECULE, s, wives. The smallest particle of a substance that has all of its chemical properties. M. consists of atoms. | adj. molecular, oh, oh. Molecular mass. Ozhegov's Explanatory Dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Ozhegov's Explanatory Dictionary
Or a particle system or a group of atoms ... Encyclopedia of Brockhaus and Efron
- [French. molecule from lat. moles mass] the smallest particle of a given substance, which has its basic chem. properties, capable of independent existence and consisting of the same or different atoms, combined into one whole chemical. connections ... Geological encyclopedia
Books
- Molecule. Building material of the Universe, Landau Lev Davidovich, Kitaygorodsky Alexander Isaakovich. The books of the Nobel Prize laureate Lev Landau and Alexander Kitaygorodsky are texts that overturn the philistine perception of the world around them. Most of us, constantly colliding ...
- Molecule Building material of the Universe, L. Landau, A. Kitaygorodskiy. Books by Nobel Prize laureate Lev Landau and Alexander Kitaygorodskiy are texts that overturn the philistine view of the world around them. Most of us, constantly colliding ...
The smallest particle of a chemical element that can exist independently is called an atom.
An atom is the smallest particle of a chemical element, indivisible only in chemical terms.
An atom is the smallest particle of a chemical element that retains all the chemical properties of this element. Atoms can exist in a free state and in compounds with atoms of the same or other elements.
An atom is the smallest particle of a chemical element that can exist on its own.
According to modern views, an atom is the smallest particle of a chemical element that has all of its chemical properties. Connecting with each other, atoms form molecules, which are the smallest particles of a substance - carriers of all its chemical properties.
In the previous chapter, our ideas about. atom - the smallest particle of a chemical element. The smallest particle of a substance is a molecule formed from atoms between which chemical forces act, or chemical bond.
The concept of electricity is inextricably linked with the concept of the structure of atoms - the smallest particles of a chemical element.
From chemistry and the previous sections of physics, we know that all bodies are built of separate, very small particles - atoms and molecules, By atoms we mean the smallest particle of a chemical element. A molecule is a more complex particle consisting of several atoms. The physical and chemical properties of elements are determined by the properties of the atoms of these elements.
The works of the English scientist John Dalton (1766 - 1844), who introduced into chemistry and the term atom itself as the smallest particle of a chemical element, became decisive in the approval of atomistic concepts in chemistry; atoms of different elements, according to Dalton, have different masses and thus differ from each other.
An atom is the smallest particle of a chemical element, a complex system consisting of a central positively charged nucleus and a shell of negatively charged particles - electrons - moving around the nucleus.
From chemistry and the previous sections of physics, we know that all bodies are built from individual, very small particles - atoms and molecules. Atoms are understood as the smallest particle of a chemical element. A molecule is a more complex particle consisting of several atoms. The physical and chemical properties of elements are determined by the properties of the atoms of these elements.
From chemistry and the previous sections of physics, we know that all bodies are built from individual, very small particles - atoms and molecules. An atom is understood as the smallest particle of a chemical element. A molecule is a more complex particle consisting of several atoms. The physical and chemical properties of elements are determined by the properties of the atoms of these elements.
Phenomena confirming the complex structure of the atom. The structure of an atom - the smallest particle of a chemical element - can be judged, on the one hand, by the signals that it itself sends in the form of rays and even particles, and on the other, by the results of bombardment of atoms of matter with fast charged particles.
The idea that all bodies consist of extremely small and further indivisible particles - atoms, was widely discussed even before our era ancient Greek philosophers... The modern concept of atoms as the smallest particles of chemical elements capable of binding into larger particles - the molecules of which substances are composed, was first expressed by MV Lomonosov in 1741 in his work Elements of Mathematical Chemistry; these views were promoted by him throughout his scientific activities... Contemporaries did not pay due attention to the works of MV Lomonosov, although they were published in the publications of the St. Petersburg Academy of Sciences, received by all major libraries of that time.
The idea that all bodies consist of extremely small and further indivisible particles - atoms, was discussed back in Ancient Greece... The modern concept of atoms as the smallest particles of chemical elements capable of binding into larger particles - the molecules of which substances are composed, was first expressed by MV Lomonosov in 1741 in his work Elements of Mathematical Chemistry; he promoted these views throughout his scientific career.
The idea that all bodies are composed of extremely small and further indivisible particles - atoms, was widely discussed even before our era by ancient Greek philosophers. The modern concept of atoms as the smallest particles of chemical elements capable of binding into larger particles - the molecules of which substances are composed, was first expressed by MV Lomonosov in 1741 in his work Elements of Mathematical Chemistry; he promoted these views throughout his scientific career.
The idea that all bodies consist of extremely small and further indivisible particles - atoms, was widely discussed by ancient Greek philosophers. The modern concept of atoms as the smallest particles of chemical elements capable of binding into larger particles - the molecules of which substances are composed, was first expressed by MV Lomonosov in 1741 in his work Elements of Mathematical Chemistry; he propagated these views throughout his scientific career.
All kinds of quantitative calculations of the masses and volumes of substances participating in chemical reactions are based on stoichiometric laws. In this regard, stoichiometric laws quite rightly relate to the basic laws of chemistry and are a reflection of the real existence of atoms and molecules that have a certain mass of the smallest particles of chemical elements and their compounds. Because of this, stoichiometric laws have become a solid foundation on which modern atomic-molecular theory was built.
All kinds of quantitative calculations of the masses and volumes of substances participating in chemical reactions are based on stoichiometric laws. In this regard, stoichiometric laws quite rightly relate to the basic laws of chemistry and are a reflection of the real existence of atoms and molecules that have a certain mass of the smallest particles of chemical elements and their compounds. Due to this, stoichiometric laws have become a solid foundation on which modern atomic-molecular theory was built.
Phenomena confirming the complex structure of the atom. The structure of an atom - the smallest particle of a chemical element - can be judged, on the one hand, by the signals it sends in the form of rays and even particles, on the other, by the results of the bombardment of atoms of matter with fast charged particles.
It should be noted that creating quantum physics was directly stimulated by attempts to comprehend the structure of the atom and the laws governing the emission spectra of atoms. As a result of experiments, it was found that in the center of the atom there is a small (compared to its size), but massive nucleus. An atom is the smallest particle of a chemical element that retains its properties. It got its name from the Greek dtomos, which means indivisible. The indivisibility of the atom takes place in chemical transformations, as well as in collisions of atoms that occur in gases. And at the same time, the question always arose whether the atom was composed of smaller parts.
The object of study in chemistry is chemical elements and their compounds. A set of atoms with the same nuclear charges are called chemical elements. In turn, an atom is the smallest particle of a chemical element that retains all its chemical properties.
The essence of this rejection of Avogadro's hypothesis was the reluctance to introduce a special concept of a molecule (particle), reflecting a discrete form of matter qualitatively different from atoms. Indeed: Dalton's simple atoms correspond to the smallest particles of chemical elements, and his complex atoms correspond to the smallest particles of chemical compounds. Because of these several cases, it was not worth breaking the whole system of views, which were based on one concept of the atom.
The considered stoichiometric laws form the basis for all kinds of quantitative calculations of the masses and volumes of substances participating in chemical reactions. In this regard, stoichiometric laws quite rightly relate to the basic laws of chemistry. Stoichiometric laws are a reflection of the real existence of atoms and molecules, which, being the smallest particles of chemical elements and their compounds, have a very definite mass. Due to this, stoichiometric laws have become a solid foundation on which modern atomic-molecular teaching is built.
