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, as they are unstable and decay into simpler atoms.

However, even atoms belonging to the same species can differ slightly from each other. Therefore, there is such a thing as chemical element 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 the Latin name of this element. For example, the chemical element hydrogen is denoted 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 of Mendeleev. Often they talk about it as a system (periodic system), because there are certain strict rules by which this or that element is placed in its cell of the table. In rows and columns periodic table regular changes in the properties of elements are observed. Thus, each element in the table has its own number.

The atoms of chemical elements do not change as a result of chemical reactions. The set of substances formed by atoms changes, but not themselves. For example, if 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 matter.

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

On Earth, the abundance of chemical elements is very different, if we consider the entire Universe. The Earth is dominated by oxygen (O) and silicon (Si). They account for about 75% of the mass of the Earth. Next come aluminum (Al), iron (Fe), calcium (Ca), sodium (Na), potassium (K), magnesium (Mg), hydrogen (H) and many other elements in descending order.

It has been established that every chemical element found in nature is a mixture of isotopes (hence they have fractional atomic masses). To understand how isotopes differ from one another, it is necessary to consider in detail the structure of the atom. An atom forms a nucleus and an electron cloud. The mass of an atom is influenced by the electrons moving at a staggering speed in orbits in the electron cloud, the neutrons and protons that make up the nucleus.

What are isotopes

isotopes A type of atom of a chemical element. There are always equal numbers of electrons and protons in any atom.

Since they have opposite charges (electrons are negative, and protons are positive), the atom is always neutral (this elementary particle does not carry a charge, it is equal to zero). When an electron is lost or captured, the atom loses its neutrality, becoming either a negative or a positive ion.

Neutrons have no charge, but their number in the atomic nucleus of the same element can be different. This does not affect the neutrality of the atom, but it does affect its mass and properties.

For example, each isotope of a hydrogen atom has one electron and one proton each. And the number of neutrons is different. Protium has only 1 neutron, deuterium has 2 neutrons, and tritium has 3 neutrons. These three isotopes differ markedly from each other in properties.

Comparison of isotopes

How are isotopes different?

They have a different number of neutrons, different masses and different properties. Isotopes have an identical structure of electron shells. This means they are pretty close. chemical properties. Therefore, they are assigned to periodic system one place.

Stable and radioactive (unstable) isotopes have been found in nature. The nuclei of atoms of radioactive isotopes are able to spontaneously transform into other nuclei. In the process of radioactive decay, they emit various particles.

Most elements have over two dozen radioactive isotopes. In addition, radioactive isotopes are artificially synthesized for absolutely all elements. In a natural mixture of isotopes, their content fluctuates slightly.

The existence of isotopes made it possible to understand why, in some cases, elements with a lower atomic mass have a higher serial number than elements with a larger atomic mass.

For example, in an argon-potassium pair, argon includes heavy isotopes, and potassium includes light isotopes. Therefore, the mass of argon is greater than that of potassium.

The difference between isotopes from each other is as follows:

1. They possess different number neutrons.
2. Isotopes have different masses of atoms.
3. The value of the mass of atoms of ions affects their total energy and properties.

What is the difference between "atom" and "molecule"? and got the best answer

Answer from Sunrise[expert]
the atom is smaller, there can be several atoms in one molecule (example - 2 hydrogen atoms and one oxygen atom = water molecule)

Answer from Diana Mamina[guru]
A molecule is made up of atoms.

Answer from NO[guru]
In addition to common places, also by birth.

Answer from aerial[newbie]
An atom is an electrically neutral system of interacting elements, consisting of a nucleus and electrons. , and a molecule is a compound consisting of 2 or more atoms

Answer from Durchlaucht Furst[guru]
Atom (other Greek ἄτομος - indivisible) - the smallest part of a chemical element, which is the carrier of its properties. An atom consists of an atomic nucleus and an electron cloud surrounding it. The nucleus of an atom consists of positively charged protons and electrically neutral neutrons, and the surrounding cloud consists of negatively charged electrons. If the number of protons in the nucleus coincides with the number of electrons, then the atom as a whole is electrically neutral. Otherwise, it has some positive or negative charge and is called an ion. Atoms are classified according to the number of protons and neutrons in the nucleus: the number of protons determines whether an atom belongs to a certain chemical element, and the number of neutrons determines the isotope of this element.
Atoms of various types in various quantities, connected by interatomic bonds, form molecules.
The concept of an atom as the smallest indivisible part of matter was first formulated by ancient Indian and ancient Greek philosophers (see: atomism). In the XVII and XVIII centuries chemists were able to experimentally confirm this idea, showing that some substances cannot be further split into their constituent elements using chemical methods. However, in the late 19th and early 20th centuries, physicists discovered subatomic particles and the composite structure of the atom, and it became clear that the atom is not really "indivisible."
Molecule (Novolatin molecula, diminutive of Latin moles - mass) - the smallest particle of a substance that carries its chemical properties.
A molecule consists of two or more atoms, is characterized by the number of atomic nuclei and electrons included in it, as well as a certain structure.
It is usually understood that the molecules are neutral (carry no electric charges) and do not carry unpaired electrons (all valences are saturated); charged molecules are called ions, molecules with a multiplicity other than unity (that is, with unpaired electrons and unsaturated valences) are called radicals.
Molecules formed by hundreds or thousands of atoms are called macromolecules. Features of the structure of molecules determine physical properties matter made up of these molecules.

Answer from Mariam Abdullah[newbie]
atoms still have an electric charge, while the molecule is neutral

Answer from Murvat Kazymov[newbie]
an atom is what a molecule is made of

In translation, "atom" means indivisible. It is named so because for a long time it was considered the smallest part of matter. But the further development of science has shown that this is not so. So, let's figure out what an atom consists of and how the atoms of various elements differ.

The structure of the atom

To date, science knows 126 types of chemical elements. The general plan of the structure of their atoms is the same. Each of them has a nucleus, consisting of protons and neutrons, around which electrons revolve. Electrons are negatively charged particles. When 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 does not have an electric charge. However, in the process of reactions, it can give an electron to other elements, turning into 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 an element. For protons and neutrons, a unifying name was coined - 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 protons never. How many protons are contained in the nucleus, you can find out by the serial number of the element in the periodic system 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 the number of protons in different atoms is different, 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 for atoms of the same element, the weight may differ due to the different number of neutrons in the nucleus. Atoms that have a different number of neutrons than 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.

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Atom and ion are elementary particles of chemical elements. These particles are the carriers of the properties of the elements. They differ in charges: the atom is neutral, and the ion is positively or negatively charged.

Definition

Atom- an electrically neutral microscopic particle of a chemical element that determines its properties. The center of an atom is a positively charged nucleus surrounded by an electron cloud, along whose orbitals electrons move. Atoms, by gaining or giving up electrons, turn into ions.

ions- microscopic electrically charged, monatomic or polyatomic and chemically active particles. They have a positive (cations) or negative (anions) charge. Ions are formed from atoms or groups of atoms that gain electrons or, conversely, lose them.

Ions are independent particles found in any states of aggregation. They are found in gases (in the atmosphere), in crystals, in liquids (both solutions and melts) and in plasma (interstellar space.)

Ions in chemical reactions able to interact with each other, with molecules and atoms. In solutions, these active particles are formed in the process electrolytic dissociation and determine the properties of electrolytes.

Comparison

An atom is always electrically neutral, an ion, on the contrary, is a charged particle. In atoms, the external energy levels, as a rule, are not completed (the group of noble gases is an exception). For ions, the outer levels are completed.

An ion, in contrast to an atom, is not capable of possessing the properties of a simple substance. For example, metallic potassium enters into a violent reaction with water, the products of which are hydrogen and alkali. And potassium ions, which are present in the composition of potassium salts, do not have similar properties. Chlorine is a yellow-green toxic gas, and its ions are non-toxic and colorless.

The color of copper is red, and its ions in solutions acquire a blue color. Iodine crystals are gray, vapors are purple, alcohol solution is red-brown, mixed with starch it gives a blue color. Iodine ions cannot change the color of starch, they are colorless.

Findings site

1. Atoms and ions of the same chemical element have different numbers of electrons.
2. The charge of atoms is zero, for ions it can be positive or negative.
3. Ions and atoms have different redox properties.