Classification of chemical substances in junior high schools, classification of chemical substances

Mixture 1,3,5 Compound 4,7 , Oxide 4, 2,6 directly composed of atoms

To do this kind of question, you need to clarify the definition of mixture, compound, oxide, and pure substance.

Pure substance: A substance composed of the same elemental substance or the same compound. Note: Pure matter does not have to be made up of a single molecule, it can be either elemental or atomic.

The difference between a pure substance and a mixture is the difference in the type of substance.

Compounds: Pure substances composed of different elements. Note: A compound must be pure, but a pure substance is not necessarily a compound.

Oxide: A compound composed of two elements, one of which is oxygen, is called an oxide. Note:

Oxides must be oxygenated compounds, but oxygenated compounds are not necessarily oxides, followed by compounds composed of two elements, which must be pure For example, KMNO4 is an oxygenated compound, but not an oxide. O2 contains oxygen, but it is elemental.

Atoms are directly constituted: elemental metals, noble gases, silicon and carbon.

There are 125 that belong to the mixture

Belongs to the 47 of the compounds

Belongs to the 4 of oxides

26 directly constituted by atoms

Of these, 1,3,5 belong to the mixture

There are 4,7 that belong to compounds, 4 that belong to oxides, and 6 that are directly constituted by atoms

Junior high school chemicals can be divided into the following three types:

1. Mixtures and purities.

1. Mixture: There are two or more substances in the composition. Common mixtures are: air, seawater, tap water, soil, coal, oil, natural gas, detonation gas and various solutions.

2. Pure substance: There is only one substance in the composition. For example, the name is "so-and-so" or "so-and-so".

Macroscopically there is one component, microscopically there is only one molecule;

Pure substances have a fixed composition and unique chemical properties, which can be expressed by chemical formulas;

Pure substances can be made up of one element (elemental) or multiple elements (compounds).

2. Elemental substances and compounds.

Elemental: A pure substance composed of only one element. It can be divided into metal element, non-metallic element and rare gas. For example, hydrogen, mercury.

Compound: A pure substance composed of two or more elements. For example, the name is "so-and-so" or "so-and-so".

3. Oxides, acids, bases and salts.

Oxide: A compound composed of two elements, one of which is the element oxygen. Oxides can be divided into metal oxides and non-metal oxides; It can also be divided into acidic oxides, basic oxides and amphoteric oxides;

Acid: A compound in which all cations ionized in solution are hydrogen ions. Acids can be divided into strong acids and weak acids; monobasic and polyacids; Oxygenated acids and anaerobic acids, etc.

Base: The cations ionized in solution are all compounds of hydroxide ions. Bases can be divided into soluble and insoluble bases.

Salt: A compound that ionizes metal cations and acid anions during ionization. Salts can be divided into normal salts, acid salts, and basic salts.

Are you talking about the classification of substances?

Elemental Elemental Metallic, non-metallic elemental.

Compounds acids, bases, salts, oxides.

There are 5 different types of substances in junior high school chemistry: elemental, oxide, acid, alkali, salt.

The five different types of substances in chemistry are generally referred to:

Elemental, oxide, acid, alkali, salt.

Hydrogen, calcium carbonate, calcium oxide, calcium hydroxide, hydrochloric acid.

Classification of chemical substances in junior high school: mixtures include air, solutions, alloys. Pure substances include: the first is elemental: metal, non-metal, and noble gas. The second is compounds: oxides, acids, bases, salts.

Mixture: is a mixture of two or more substances (or composed of different substances). For example, air, solutions (hydrochloric acid, clarified lime water, iodine wine, mineral water) minerals (coal, oil, natural gas, iron ore, limestone), alloys (pig iron, steel).

Pure: Composed of one substance. For example:

Water, mercury, blue alum (CUS04.)5h20) are pure, ice mixed with water is pure. Those with "so-and-so" and "so-and-so" in the name are pure substances and compounds.

Elemental: A pure substance composed of the same kind (or one) elements. For example:

Iron, oxygen (liquid oxygen), hydrogen, mercury.

Compound: A pure substance composed of different elements (two or more). It is a compound with "so-and-so" and "so-and-so" in the name.

Elemental, oxide, acid, alkali, salt. Elemental matter is a pure substance composed of the same element; Oxides are chemical compounds (which must be pure, of course); Acids are also acids in compounds that produce all cations (H+) during ionization, or substances that dissolve in water and release protons to form H3O+ (hydronium ions).

In the acid-base ionization theory, alkali refers to the fact that all the anions ionized in the aqueous solution are oh-; In acid-base proton theory, a base refers to a substance that can accept protons; In acid-base electron theory, a base refers to an electron donor.

In chemistry, salt refers to a class of metal ions or ammonium ions (NH+) combined with acid ions of compounds, such as calcium sulfate, copper chloride, sodium acetate, generally speaking, salt is the product of metathesis reaction, such as sulfuric acid and sodium hydroxide to produce sodium sulfate and water, there are also other reactions to form salts, such as displacement reactions.

Salt is divided into single salt and combined salt, single salt is divided into normal salt, acid salt, basic salt, and combined salt is divided into double salt and complex salt. Among them, the acid salt contains hydrogen ions in addition to metal ions and acid ions, and the basic salt contains hydroxide ions in addition to metal ions and acid ions. When complex salts are dissolved in water, complex salt complexes of complex ions that are different from the original salts can be generated.

I'm also a junior high school student

The teacher has already told me

It's very simple、Substances are divided into pure substances and mixtures

Pure substances are divided into elemental substances and compounds

Elemental elements are divided into metallic and non-metallic elementals

Metal elements such as: Fe [iron] mg [magnesium].

Non-metallic elements such as: H2 [hydrogen] O2 [oxygen].

Compounds are divided into oxides and others

Oxides such as: CO2 [carbon dioxide] SO2 [sulfur dioxide] (oxide refers to a substance composed of two elements, one of which is oxygen), others such as: NH3 [ammonia] H2SO4 [sulfuric acid].

I'm also in my third year of junior high school.

Pure substances and mixtures, such as oxygen in the air, nitrogen or something is a mixture, and distilled water is a pure substance, a substance, magnesium oxide is also a thing, pure substances are divided into elemental and compounds, elemental is an element, and compounds are many elements.

For example, Fe is elemental, and Fe50 is also elemental, because the element does not change, MGO is a compound, and a variety of elements.

Oxide is a substance with two elements, one of which is oxygen, for example, MGO magnesium oxide is three elements or something, there can only be two elements!

Exams are generally these, well.

Only one chemical formula can be written as pure, and as many as a mixture. (There is only one substance pure.) multi-substance mixtures).

Pure matter of only one element is elemental (note that the premise is pure. It would be wrong to say that a substance with only one element is elemental) that a substance with multiple elements is a compound.

I haven't learned about acid-base salts yet, so just pay attention to the oxides in the compounds. There are only two elements, one of which is oxygen. (It is wrong to think that oxygenated is oxide).

>> When you encounter a classification problem, practice like this: first determine whether it is a mixture or a pure substance, if it is a pure substance, then determine whether it is an element or a compound, if it is a compound, determine whether it is an oxide, and then determine whether it is a metal oxide or a non-metal oxide. If you don't do this ten times, you'll be all right.

Mixture of substances.

Elemental purity.

Compounds (oxides...)

Can you see it?