Translated, “atom” means indivisible. It is named so because for a long time it was considered the smallest part of matter. But further development of science showed that this is not so. So, let's figure out what an atom is made of and how the atoms of different elements differ.

Atomic structure

To date, science knows 126 species chemical elements. The general structure of their atoms is the same. Each has a nucleus of protons and neutrons around which electrons orbit. Electrons are negatively charged particles. As they rotate around the nucleus, an electron cloud is formed.

Protons are positively charged particles. At rest, an atom contains the same number of protons and electrons, so such a chemical element has no electrical charge. However, during reactions, it can give electrons to other elements, becoming a positively charged particle, or take them away, becoming a negatively charged particle. Neutrons do not carry any charge, but they affect the mass of the element. A unifying name was invented for protons and neutrons - nucleons.

Atoms of various elements

Atoms of different elements differ from each other in the number of protons in the nucleus. The number of electrons can change, but the number of protons never. How many protons are contained in the nucleus can be determined by the element's serial number in the periodic table of Mendeleev. Hydrogen (No. 1) has 1 electron and 1 proton at rest, lithium
(No. 3) - 3 electrons and 3 protons, carbon (No. 6) - 6 electrons and 6 protons.

Since different atoms have different numbers of protons, their masses also differ. The mass of an element is mainly formed by protons and neutrons, because the weight of electrons is negligible. But even atoms of the same element may have different weights due to different quantities neutrons in the nucleus. Atoms in which the number of neutrons differs from the number of protons are called isotopes. For example, in nature there are carbon atoms C12 (6 protons and 6 neutrons), C13 (6 protons and 7 neutrons) and other varieties with a neutron content from 2 to 16.

OTHER

The foreign word “alpha” has firmly taken root in the Russian language and is found in a variety of combinations. About,…

Of course, each of us, in the most general sense, has a good idea of ​​what an element is. An element is a component...

The word "core" means the core of something, shaped like a ball. However, the meaning of this concept can be different, in ...

Each of us, at least once, admired the beautiful night sky, strewn with many stars. Have you ever thought about…

The definition of the Large Hadron Collider is: the LHC is a charged particle accelerator, and it was created for the purpose of...

An electron is an elementary particle that has a negative electrical charge. It is equal to -1. The electron enters...

There is an invisible force that flows within biological objects and inanimate environments. This force is called...

Not many people are well versed in the various terms, theories and laws of physics and chemistry. And some, maybe...

Reactions between different kinds chemicals and elements are one of the main subjects of study in chemistry.…

The concept of matter is studied by several sciences at once. We will analyze the question of what substances are from two points...

In chemistry lessons at school, they teach you how to solve various problems, popular among which are calculation problems...

Electric charge is a physical quantity that determines the body’s ability to take part in electromagnetic...

The oxidation state is the conditional charge of an atom in a molecule, the atom receives it as a result of the complete acceptance of electrons, its...

The ancient Greeks knew that all substances consist of particles. Around 420 BC e. The philosopher Democritus proposed that matter consists of tiny, indivisible particles called atoms. All substances are made up of atoms and molecules. Both the atom and the molecule were initially considered indivisible, and only later was it proven that this was not the case. How does an atom differ from a molecule?

Atoms- These are the smallest particles that make up a substance.
Molecules– these are also the elementary particles that make up any substance.

Comparison of atom and molecule

What is the difference between an atom and a molecule?
An atom is an elementary particle of matter. It has its own mass and size and is responsible for the properties of this substance as a chemical element. An atom consists of a nucleus and electrons that move in their orbits around the nucleus. It is the structure of the atom that determines the chemical properties of a substance. Atoms do not occur in a free state. They bind together and form molecules due to the electrical charges of the particles they are made of.
A molecule is what a substance is made of. Molecules can contain two or more atoms that are connected to each other by interatomic bonds. More precisely, we can say that the molecule consists of atomic nuclei and internal electrons that move in their orbits, as well as external valence electrons. Different molecules contain different numbers of atoms of a certain type and different quantities. The molecule has a complex architectural structure, where each atom has its own place and its own well-defined neighbors. The properties of a molecule are determined by how many atoms it contains. These properties are influenced by the order and configuration of the connection of atoms. The atomic structure that forms a molecule can be rigid, but not in all cases. Each atom is in continuous motion, it oscillates around its equilibrium position. In this case, a free molecule during its thermal movement has different configurations. The molecule is electrically a neutral particle. It is the smallest particle of matter that has its chemical properties. In the case of monatomic molecules such as noble gases, the properties of the molecule and the atom are the same. Atoms in a molecule are combined chemical bonds. Such a bond can be created by one or more pairs of electrons shared between two atoms. The molecule can exist independently.

How is an atom different from a molecule?

Atoms form a molecule. An atom consists of a nucleus and electrons that move in their orbits around the nucleus.
Molecules are made up of atoms.
An atom has an electric charge, but a molecule is neutral.
Only a molecule can exist independently.

All the matter around us that we see is made up of various atoms. Atoms differ from each other in structure, size and mass. There are more than 100 types of different atoms, more than 20 types of atoms were obtained by man and are not found in nature, since they are unstable and decay into simpler atoms.

However, even atoms belonging to the same type can differ slightly from each other. Therefore, there is such a thing as a chemical element - these are atoms of the same type. They all have the same nuclear charge, that is, the same number of protons.

Each chemical element has a name and designation in the form of one or two letters from Latin name this element. For example, the chemical element hydrogen is designated by the letter H (from the Latin name Hydrogenium), chlorine - Cl (from Chlorum), carbon - C (from Carboneum), gold - Au (from Aurum), copper - Cu (from Cuprum), oxygen - O (from Oxigeium).

The existing chemical elements are listed in the Periodic Table. It is often referred to as a system (periodic table), because there are certain strict rules by which this or that element is placed in its table cell. Regular changes in the properties of elements are observed in the rows and columns of the periodic table. Thus, each element in the table has its own number.

Atoms of chemical elements do not change as a result of chemical reactions. The set of substances formed by atoms changes, but not the atoms themselves. For example, if as a result of a chemical reaction carbonic acid (H 2 CO 3) decomposed into water (H 2 O) and carbon dioxide (CO 2), then no new atoms were formed. Only the connections between them have changed.

Thus, an atom can be defined as the smallest chemically indivisible particle of a substance.

The most abundant element in the universe is hydrogen, followed by helium. These are the simplest chemical elements in structure. The remaining chemical elements account for about 0.1% of all atoms. However, the atoms of other chemical elements have greater mass than the atoms of hydrogen and helium. Therefore, if we express the content of other chemical elements in the Universe in mass percentages, then they will account for 2% of the mass of the total matter of the Universe.

On Earth, the abundance of chemical elements differs greatly when considering the entire Universe. Oxygen (O) and silicon (Si) predominate on Earth. They account for about 75% of the Earth's mass. Next in descending order are aluminum (Al), iron (Fe), calcium (Ca), sodium (Na), potassium (K), magnesium (Mg), hydrogen (H) and many other elements.

Many centuries ago, people realized that any substance on earth consists of microscopic particles. Some time passed, and scientists proved that these particles really exist. They were called atoms. Usually atoms cannot exist separately and are combined into groups. These groups are called molecules.

The name “molecule” itself comes from the Latin word moles, meaning heaviness, block, bulk, and the diminutive suffix - cula. Previously, instead of this term, the word “corpuscle” was used, literally meaning “ small body" In order to find out what a molecule is, let's turn to explanatory dictionaries. Ushakov’s dictionary says that this is the smallest particle that can exist autonomously and has all the properties of the substance to which it belongs. Molecules and atoms are all around us, and although we can't touch them, all we really see are giant clumps of them.

Example with water

The best way to explain what a molecule is is to use the example of a glass of water. If you pour half of it, the taste, color and composition of the remaining water will not change. It would be strange to expect anything different. If you cast half again, the quantity will decrease, but the properties will again remain the same. Continuing in this manner, we will end up with a small droplet. It can still be divided with a pipette, but this process cannot be continued indefinitely.

Ultimately, you will get the smallest particle, the remainder of which will no longer be water. To get an idea of ​​what a molecule is and how small it is, try to guess how many molecules are in one drop of water. How do you think? Billion? One hundred billion? In fact, there are about a hundred sextillion of them. This is a number that has twenty-three zeros after the one. Such a magnitude is difficult to imagine, so let’s use a comparison: the size of one is smaller than a large apple by as many times as the apple itself is smaller. Therefore, it cannot be seen even with the most powerful optical microscope.

and atoms

As we already know, all microscopic particles, in turn, consist of atoms. Depending on their number, the orbits of the central atoms and the type of bonds, the geometric shape of the molecules can be different. For example, human DNA is twisted in the shape of a spiral, and the smallest particle of ordinary table salt looks like this: If several atoms are somehow taken away from a molecule, its destruction will occur. At the same time, the latter will not go anywhere, but will become part of another microparticle.

After we have figured out what a molecule is, let's move on to the atom. Its structure is very similar to a planetary system: in the center there is a nucleus with neutrons and positively charged protons, and electrons revolve around it in different orbits. In general, the atom is electrically neutral. In other words, the number of electrons is equal to the number of protons.

We hope our article was useful, and now you no longer have questions about what a molecule and an atom are, how they are structured and how they differ.

Atom thing (Garg et al 2014); an element is a type of thing.

An atom is a collection of protons, neutrons and electrons. One isolated atom in the neutral state has some protons, the same number of electrons, and some neutrons (about the same number as protons for lighter elements, about 50% more for heavier elements). The number of neutrons or protons in an atom only changes as a result of radioactive processes or very high-energy interactions, such as you get in particle accelerators. And I mean really High Energy: Even if you think about blowing up sticks of dynamite, that's not enough energy to start messing around with protons and neutrons. Chemistry occurs when atoms combine and exchange electrons or give electrons to each other. Chemical reactions happen all the time, and many of them don't require much energy: moving electrons from atom to atom is often very simple.

So, the chemistry of an atom depends on the number of electrons, and the number of electrons in an isolated atom directly depends on the number of protons. Electrons are so easy to add and remove from atoms (just rub a balloon on your hair: static electricity is you transferring electrons between your hair and balloon), so we classify atoms according to the number of protons they have. Neutrons are not so relevant: I will talk about them at the end.

So the element an atom is determined by the number of protons. All hydrogen atoms have one proton, and all atoms with one proton are hydrogen. Two protons are helium, three are lithium, seventeen are chlorine, 79 are gold, etc. A pure sample of an element contains only atoms of this type: for example, a pure sample of iron contains only atoms with 26 protons. On the other hand, water is not an element: a water molecule consists of two hydrogen atoms (one proton each) sharing electrons with an oxygen atom (eight protons).

Now, what does it mean to say that an element "cannot be broken down into a simpler form" and why are atoms not a "simpler form"? Well they are not a simpler form because the iron atom - iron: it's the same shape, it's not simpler. Think of it this way. If I give you a piece of pure iron, all you can do is break it into smaller pieces of iron or make it into a more complex substance, such as allowing it to rust. - Rust is formed from iron and oxygen. The smallest possible piece of iron you could make is a single atom of iron, but that's still just an incredibly tiny piece of iron. If you wanted to break a piece of iron beyond the individual iron atoms, you would need to use a nuclear reactor or a particle accelerator or something like that, and then finally you could get something that wasn't iron because you would change number of protons in atoms.

Let's compare this to water. If I give you a bucket of clean water, then, like a piece of iron, you can break it down into smaller and smaller samples, ending up with a single molecule of water. But you can do something else: if you pass electricity through water, it splits into pure hydrogen and pure oxygen. These are "simpler" substances because each is made up of atoms of only one element, whereas water has atoms of two elements.

What about neutrons? Well, in terms of chemistry, they don't do much, but atoms with the same number of protons, but with different number neutrons are much more similar (they have essentially the same chemistry, for example) than atoms, which have the same number of neutrons, but different quantity protons. It makes much more sense to classify by the number of protons, since this determines the number of electrons and determines the chemistry.

Suppose you tried to classify atoms according to the number of neutrons. Best of all, most argon atoms (18 protons) have 22 neutrons, but some chlorine atoms (17 protons) and a fair share of potassium atoms (19 protons) also have 22 neutrons. As you probably know, argon, chlorine and potassium are completely different from each other. On the other hand, potassium atoms with 22 neutrons behave almost identically to the most common kind of potassium atoms, which have 21 neutrons.