Chemical phenomena determine chemical substances, what are chemical phenomena

In chemical reactions, it is often determined whether a chemical reaction occurs based on the phenomenon that accompanies the reaction.

The process by which molecules break down into atoms, and the atoms rearrange and combine to form new substances, is called a chemical reaction. In the reaction, it is often accompanied by luminescence, heat, discoloration, and the formation of precipitate, etc., and the basis for judging whether a reaction is a chemical reaction is whether the reaction generates new substances. But nuclear reactions are not chemical reactions.

In the reaction, it is often accompanied by luminescence, heating, discoloration, and the formation of precipitates. The basis for determining whether a reaction is chemical is whether the reaction produces a new substance. According to the theory of chemical bonds, it can be judged whether a chemical reaction is based on whether there is the breaking of old bonds and the formation of new bonds in a change process.

According to the type of reactants and products, it is divided into four categories: chemical reaction, decomposition reaction, displacement reaction, and metathesis reaction.

According to the gain and loss of electrons, it can be divided into: redox reaction, non-redox reaction; Redox reactions include: self-redox, and the reaction of the reducing agent with the oxidant.

Isomerization: (a b): A compound is the formation of a structural recombination without changing the chemical composition.

I can't understand what you said in my third year of junior high school, but I started with special reaction conditions and special substances when I did the inference questions, and then I found a breakthrough in connection with the substances I often see, and then I don't know how you guys are.

These require you to memorize the chemical and physical properties of some common substances, do more inference questions in this regard, and then summarize them yourself, so that you will improve.

The most important thing is to do more questions.

The chemical properties are basically determined by the outer electron shell of the nucleus, and the physical properties involve a wide range, which are related to the electrons outside the nucleus, the intermolecular force, the electromagnetic force, etc., but the things that we can contact and the properties that can be used in our daily life are actually determined by the outer electron shell of the nucleus.

Solid matter has shape and volume, and their molecules are tightly bound together. Liquid substances also have volume, but no shape, in contrast, their molecules are loosely bound so that liquids can be poured into a container to measure their volume.

Gases have neither volume nor shape, and their molecules move freely, thus filling any container that can seal them. The plasma state is made up of an equal amount of negatively charged electrons and positively charged ions. A Bose-Einstein condensate is a sudden "condensation" of atoms in different states to the same state (usually the ground state).

That is, atoms in different states "condense" to the same state.

The most important factor that determines the chemical properties of a substance is the number of outermost electrons of the atoms that make up the substance.

Determine the physical properties of the substance, such as density, specific heat capacity, thermal conductivity, electrical conductivity, etc.

The number of electrons in the outermost shell determines the chemical properties.

Vaguely remember that chemical properties are determined by the distribution of electrons outside the nucleus, while physical properties are determined by the arrangement of atoms. How to analyze it exactly.

I forgot, this answer is only for reference!

Chemical phenomena are often accompanied by luminescence, exothermy, discoloration, precipitation and gas release.

It is important to note that when these phenomena occur in a change of matter, it is not necessarily a chemical change. In the phenomenon of luminescence and heat release, the lamp emits light and heat when it is energized, but it is a physical change.

Therefore, the essential difference between chemical change and physical change is that there is a new substance after the chemical change, and there is no new substance after the physical change.

1. The explanation of the phenomenon of the problem is as follows:

It refers to the phenomenon that occurs in the process of cracking molecules into atoms, rearranging and combining atoms to form new molecules, and at the same time, the chemical phenomena produced by this process are often accompanied by the appearance of luminescence, exothermy, discoloration, precipitation and the release of gases.

2. The opposite of chemical phenomena is physical change, and the method of distinguishing them is introduced as follows:

When the occurrence of these phenomena in the material change, it is not necessarily a chemical change, such as luminescence and exothermic phenomenon, when the electric lamp is energized, it is a physical change, so the essential difference between chemical change and physical change is that there is a new substance after the chemical change, and there is no new substance after the physical change.

1. The explanation of chemical phenomena is as follows:

It refers to the phenomenon that occurs in the process of cracking molecules into atoms, and the atoms are re-arranged and combined to form new molecules, and the chemical phenomena produced by this process are often accompanied by the emergence of luminescence, exothermy, discoloration, precipitation and the release of gases.

2. The opposite of chemical phenomena is physical change, and the method of distinguishing them is introduced as follows:

When these ruler phenomena occur in material changes, it is not necessarily a chemical change, such as luminescence and heat release phenomena, when the electric lamp is energized, it is a physical change in the chain, so the essential difference between chemical change and physical change is that there is a new substance after the chemical change, and there is no new substance after the physical change.

A chemical reaction is when two or more substances react together to produce a new substance, which is called a chemical change.

Physical change means that when various substances are together, no new changes occur.

The microscopic explanations of chemical reactions are all failures of theosophy in the material base. Even the nature of chemical reactions can be explained by physical phenomena. Chemical reactions must have physical reactions, and chemical reactions are actually just electric problems under the action of some electric fields.

A branch of chemical physics, so whenever there is a chemical change, there must be a physical change, but there is not necessarily a chemical change when there is a physical change.

The chemical properties of a substance, depending on the composition and structure of the substance. For substances composed of molecules, the characterization of their chemical properties depends on the composition and structure of the molecules, and the corresponding chemical properties can only be exhibited when the composition and structure of the molecules change.

For atomic crystals, their chemical properties are not characterized in molecular form, such as Fe, which is composed of only iron atoms, and its chemical properties depend on the extranuclear electron configuration of iron atoms, not on the structure of the molecule, as in the case of molecules.

For ionic crystals, such as NaCl, do you say it has a molecular form? They are coupled to each other in ionic form to form ionic bonds, which are then aggregated to form a crystal lattice, thus revealing the corresponding chemical properties of the cavity.

Saying that a molecule is the smallest particle that maintains the chemical properties of a substance is a category that can be understood at the secondary school level, and I also said it on the first floor, so I won't go into details, thank you!

It is determined by the creation of new matter by one object and another.

The property of a substance that manifests itself in a chemical change is flammability.

Specific analysis: 1. The properties of substances in chemical changes are called chemical properties, such as flammability, combustibility, oxidation, reduction, acidity and alkalinity.

2. The properties that matter exhibit without chemical changes are called physical properties. Physical properties are often manifested as: color, state, odor, density, hardness, melting point, boiling point, electrical conductivity, thermal conductivity, solubility, volatility, adsorption, etc.

3. This test center examines the distinction between physical properties and chemical properties, to memorize the properties of matter, and be able to apply them on the basis of comparison.

Flammability: 1. The flammability of a substance, that is, the risk of combustion, depends on its flash point, spontaneous ignition point, ** (combustion) limit and heat of combustion. The presence of combustible gas alarms is mainly aimed at the workplace:

For example, chemical enterprises generally set up coal gasification devices, gas conversion devices, gas purification devices, and by-product flammable storage devices.

2. Under the specified test conditions, the material or product can be burned with flame. It includes a number of characteristics related to whether the mask ignites easily and whether it can maintain its ability to burn. It is easy to ignite depending on the situation that the flammable gas is released after the external fire reed leaks the flame to heat the material; Whether the combustion can be maintained depends on whether the material combustion heat can heat the surrounding materials, and continue to release the bridge to make a noise of combustible gas.