Does the concept of molecules in chemistry, strictly speaking, still exist?

A molecule is the smallest particle that maintains the chemical properties of a substance.

Understanding of the Concept:

a."Keep" means that each molecule that makes up a substance is chemically identical to that substance. For example, oxygen molecules maintain the chemical properties of oxygen, and water molecules maintain the chemical properties of water.

The molecules of the same substance have the same chemical properties. The molecules of different substances have different chemical properties, such as the different chemical properties of oxygen O2 and carbon dioxide CO2, which can prove that the constituent molecules of oxygen and carbon dioxide are different, and there are no oxygen molecules in carbon dioxide.

b."Chemical properties": The properties of substances are divided into physical and chemical properties.

Molecules can only maintain the chemical properties of the substance. The physical properties such as state, density, melting point, boiling point, etc., are all properties expressed by the aggregation of a large number of molecules of the substance, which are macroscopic and cannot be expressed by every single molecule. For example, the chemical properties of oxygen are the properties of each oxygen molecule that makes up oxygen, and the physical properties of oxygen are the properties of the aggregation of a large number of oxygen molecules that make up oxygen, and a single oxygen molecule does not maintain the physical properties of oxygen.

The macroscopic representation of the physical properties of matter is also different depending on the way in which the molecules that make up matter are aggregated. At this point, if the molecules of the substance do not change, the chemical properties maintained by the molecules also remain the same. For example, under the condition of changing temperature and pressure, the molecular aggregation mode of oxygen changes, resulting in a change in the physical properties of oxygen, such as the state can change from gaseous to liquid or solid, and the color can change from colorless to light blue.

But at this time, since the molecule itself has not changed, the chemical properties remain the same.

c."Smallest particle": A substance made up of molecules that chemically changes to form other substances, and the molecules that make up the original substance change to become molecules of other substances.

The changed molecule cannot maintain the chemical properties of the original substance, so from the perspective of maintaining the chemical properties of the original substance, the molecule is the smallest particle that maintains the chemical properties of the substance. Other particles, such as "atoms, ions", etc., will be studied in later chapters. Here "smallest particle" should be understood as "smallest of them".

Note: In a substance made up of molecules, the molecule is the smallest particle that maintains the chemical properties of the substance. For example, an oxygen molecule is the smallest particle that retains the chemical properties of oxygen.

Atoms are the smallest particles in chemical change.

Understanding of the Concept:

a."Smallest particle" is in the context of "chemical change". During chemical change, atoms can no longer be divided and are the smallest particles. But if chemical changes are not taken into account, atoms can also be divided into smaller particles such as protons, neutrons, electrons, etc.

b.In the process of chemical change, the atom is the smallest particle means that the type of atom remains the same in the chemical change, that is, the protons and neutrons in the nucleus of the atom do not change, but the number of electrons outside the nucleus of the atom, especially the number of electrons in the outermost shell, changes.

Atom: The atom is the smallest unit of constituent elements and the most elementary particle in a chemical reaction, and different atomic nuclei determine different atomic types, the number of protons determines what element the atom is, and the number of neutrons determines what isotope it is. The electrons in the atom determine the type of chemical reaction that takes place between the elements and the substances that are made up between them.

Landlord: What you see on the periodic table are all the elements that are known to be atomic.

A molecule, on the other hand, is a cluster of atoms that is "glued" together by two or more atoms through chemical bonds (to put it bluntly, a "chain" composed of electrons), which can exist separately and maintain the physical and chemical properties of matter. And these clusters of atoms can be combined by the van der Waals force to form a more macroscopic substance. For example, the water molecule that makes up water, which is a small group of two hydrogen atoms and one oxygen atom, which maintains the physical properties of water in a transparent and liquid state, and maintains the neutral and stable chemical properties in water.

In chemical reactions, molecules are separable and atoms are indivisible.

A molecule is a kind of particle that exists independently and maintains the chemical properties of a substance. Molecules have a certain size and mass; There is a certain interval between molecules; Molecules are always in constant motion; There is a certain force between molecules; Molecules can make up matter; Molecules can also be divided into smaller particles in chemical changes: atoms; Molecules can change the size of the interval as the temperature changes.

The properties of the same kind of molecule are the same, and the properties of different kinds of molecules are different. Large molecules can have a relative molecular mass of more than several million. Molecules with a relative molecular mass of more than several thousand are called polymers.

A molecule is a tiny unit that makes up a substance, and it is the smallest particle that can exist independently and maintain all the original chemical properties of the substance. Molecules are generally made up of smaller particles – atoms. Atoms are the smallest particles in chemical change.

Although atoms are small and cannot be redivided by chemical methods, they can still be redivided by other methods because atoms also have a certain composition. Atoms are composed of a positively charged nucleus in the center and negatively charged electrons outside the nucleus (antimatter is the opposite), and the nucleus is composed of two particles, protons and neutrons, and the electrons move at high speed in a large space outside the nucleus.

Atoms are combined into molecules in a certain order and arrangement by a certain force. In the case of water molecules, for example, the smallest unit that appears is a water molecule (H2O) composed of two hydrogen atoms and one oxygen atom until the properties of water are continuously separated until the properties of water are not destroyed. A water molecule can be divided into two hydrogen atoms and one oxygen atom by electrolysis or other methods, but its properties are completely different from those of water.

Some molecules are made up of only one atom, called monoatomic molecules, such as helium and argon, which are both atoms and molecules. Molecules made up of more than two atoms are collectively referred to as polyatomic molecules.

Molecules are made up of atoms, and both molecules can directly form matter. Atoms are the smallest particles in chemical change and are indivisible in chemical change. A molecule is the smallest particle that maintains the chemical properties of a substance, and a change occurs when the chemical properties of the molecule change.

The difference is that a molecule is the smallest particle that maintains the chemical properties of a substance, and an atom is the smallest particle in a chemical change . The connection is that molecules are made up of atoms (that writes = = you are illiterate!). Concept. I'm working on this question as well....There is no specific book either.

Connection: Molecules are made up of atoms.

Difference: In chemical change (premise), molecules can be divided, atoms can no longer be divided.

Difference: In chemical change, molecules can be redivided, but atoms cannot be redivided.

Contact: 1Molecules are made up of atoms.

2.Molecules and atoms can directly constitute matter.

Molecules can be redivided in chemical reactions, but atoms cannot.

The first sub-question of the last question.

.Concept.

A molecule is the smallest particle that maintains the chemical properties of a substance. That is, when the molecule changes, the substance changes, and the chemical properties of the substance also change. For example:

Oxygen is flammable, and this chemical property is maintained by oxygen molecules, and if oxygen molecules become other molecules, the chemical properties are also changed. In the same way, hydrogen molecules retain the chemical properties of hydrogen, and the chemical properties change when hydrogen molecules become other molecules. In general, the chemical properties of any substance are maintained by the molecules of the substance.

Atoms are the smallest particles in chemical change. The essence of chemical change is that the molecule is divided into atoms, and the atoms cannot be redivided, but only recombined into new molecules.

It can be seen that in chemical change, atoms are indivisible and are the smallest particles, which are only recombined into new molecules. Note that the premise of saying that atoms are smallest is that they are smallest in chemical change. As for the atom itself, it can still be redivided.

2.Difference: In chemical change, molecules can be divided into atoms, and atoms can not be divided again.

3.Connection: A molecule is made up of atoms, a molecule can be divided into atoms, and atoms can form molecules.

A molecule is the smallest unit of a substance that can exist independently, be relatively stable, and maintain the physical and chemical properties of the substance. Molecules are made up of atoms, which are bound together into molecules in a certain order and arrangement through a certain force. Xiang Tie key.

Atoms refer to the basic particles of chemical reactions, and atoms are inseparable in chemical reactions. The atomic diameter is on the order of 10 -10m. Atoms have very small masses and are concentrated in the nucleus.

Electrons are distributed outside the nucleus to produce a spectrum of electron transitions, which determine the chemical properties of an element's branches and have a great influence on the magnetic properties of atoms. All atoms with the same number of protons make up the elements, and each element has at least one unstable isotope.

Radioactive decay is possible. The atom was the first to have an ontology in philosophy.

With the progress of human understanding, the atom has gradually become a scientific theory from an abstract concept.

Molecules are the smallest particles that maintain the chemical properties of a substance.

Atoms are the smallest particles in chemical change.

A molecule is the smallest particle in a chemical change. Atoms are the smallest particles in a chemical reaction. 、，

In chemical changes, molecules can be divided into atoms, but Qi Zhaogao and Chaila atoms can no longer be divided, but can only be reconstituted into new molecules or particles

So the answer is: molecule; Atomic

In chemical change, the molecule is going to change, so the molecule is the smallest particle that maintains the chemical properties of the substance. Substances made up of atoms, such as noble gases and metals, are made up of atoms that retain their chemical properties.

Substances made up of ions: Sodium chloride, for example, is made up of sodium ions and chloride ions to maintain its chemical properties. Don't say that atoms or ions are smaller than molecules.

Moreover, at the time when this concept was proposed, people thought that matter was composed of molecules, so it was correct to say that molecules were the smallest particles that maintained the chemical properties of matter!

Matter is made up of molecules or atoms. That is, some substances are made up of molecules, such as gases.

Cl2, etc., some are made of atoms, such as metals, Fe, etc. The change of properties means that if it is a substance composed of atoms, the properties of the atoms change, and the properties of the matter that are composed of them also change, as do the molecules.

Chemical molecules actually include physical molecules and atoms, for chemical reactions, atoms are the smallest constituent substances, chemical reactions in the junior high school stage of understanding is the rupture of material molecules and the formation of new material molecules, and atoms do not change their physical and chemical properties in the reaction process!

I don't know if you get it!

That is to say, the chemical properties of a substance made up of molecules are expressed by the molecules that make it up.

The chemical properties of a substance made up of atoms are expressed by the atoms that make it up.

Ever heard of gas poisoning? Gas poisoning is actually carbon monoxide poisoning. Carbon monoxide gas is made up of an infinite number of carbon monoxide molecules. The molecular formula of carbon monoxide is CO (you should know what is called molecular formula), once C and O in CO

If separated, it will not poison people (that is, it does not have the properties of poisoning people). This is where the molecule is to maintain the chemical properties of the substance. But some substances are directly made of atoms and there are no molecules in them, so "molecules" are added after "or atoms".

As for how you say to change, that's not your stage, and I can explain it to you in one or two clicks!

Quite simply, a certain atomic or molecular composition determines a certain property. The so-called maintenance means that the chemical properties cannot be changed under the condition that the composition and configuration of the molecule remain unchanged, and the essence of the chemical reaction is the reorganization of atoms, that is, the composition and configuration of the molecule or atom are changed after the reaction to form a new substance, so the same properties cannot be maintained.

In short, the last sentence concludes that structure determines properties, has a great impact on chemical properties, and has a great impact on physical properties, which are determined by the combination of different atoms into different molecules, and at the same time have a variety of different molecular structures and atomic structures.

To put it simply, an atom is made up of nuclei and electrons. Among them, there is only one nucleus (the nucleus is composed of protons and neutrons), and there can be more than one electron, and the number of electrons varies depending on the type of atom.

A molecule is made up of multiple atoms in different valence bond ways.

An atom is the smallest unit of a chemical reaction and is made up of the nucleus and electrons outside the nucleus! A molecule is made up of several atoms that are the same or different!