1. Allotrope 1. Meaning: Several elements of different properties formed by the same element are called allotropes of this element, such as diamond, graphite and C60, are allotropes of carbon, and oxygen and ozone (O3) are allotropes of oxygen element. 2. The reason for the produ

1. Allotrope

1. Meaning: Several different properties elemental , called allotrope

such as: Diamond , graphite and C60 is an allotrope of carbon element, oxygen and ozone (O3) are allotrope of oxygen

2. The reasons for the production of allotrope

(1) The number and bonding methods of atoms that make up molecules are different, such as: oxygen (O2) and ozone (O3)

(2) The atoms are arranged in different ways, , such as: Diamond and graphite

3, research object

(1) Allotropes refer to elemental substances, not compound

(2) Different elements that are allotropes are composed of the same element, and the nuclear charge number is the same

html that constitute their atoms . The nuclear charge number is the same

4. The meaning of "same" and "different" of allotropes

(1) "same" - refers to the same elements;

(1) "different" - refers to the formation of different elements, different structures, and different properties

5. The "structure determines properties" of allotropes

(1) The structure of allotropes is different, and there are differences in properties

(2) Different physical properties, some chemical properties are similar, some have large differences

6. Mutual conversion: The transformation between allotropes involves both elemental and elemental generation. The transformation between them is a chemical change, but there is no change in compound valence

2. Classification method of substances

1. Substance classification standard: Classify substances. First, determine the classification standard, and then classify them according to the standard

. Classify the following compounds: ①NaCl　②HCl　③CaCl2　④CuO　⑤H2O　⑥Fe2O3

(1) According to the standard of the existence status of the substance under normal conditions, it can be divided into solids: ①③④⑥, liquid: ⑤, gas: ②

(2) According to the elemental composition of the substance, it can be divided into chloride : ①②③, oxide: ④⑤⑥

(3) According to the composition and properties of the substance, it can be divided into acid: ②, salt: ①③, oxide: ④⑤⑥

2, cross-classification method: Classification of the same substance according to different standards

such as: Na2CO3 From the perspective of the cation it consists of sodium salt. From the perspective of the anion it consists of carbonate

3. Tree classification method: Reclassify similar things according to certain standards

such as: Classification of substances (Based on composition and properties)

① Elemental substance must be a substance composed of the same element, and substance composed of the same element may not be a single substance

② Compounds must be pure substance composed of different elements, but pure substances may not be compound

③ Pure substances are substances composed of one component (molecule), with chemical formulas, fixed melting, boiling point

④ Mixture is a substance composed of multiple components (molecules). It has no chemical formula, no fixed melting, boiling point

3. Classification of substances

1, Classification of elemental substances

2,

2, html Classification of l4 oxide

(1) acid oxide : react with alkali to produce oxides that can only produce salt and water. Acid oxides are also called acid anhydride

such as : CO2 is carbonic acid acid Anhydride, SO3 is an acid anhydride of sulfuric acid

(2) alkaline oxide : react with acid and can only produce salt and water oxide

examples : CaO and Fe2O3 are both alkaline oxides

① Basic oxides must be metal oxides, but metal oxides are not necessarily alkaline oxides., such as : Mn2O7 is an acidic oxide, Na2O2 is an peroxide , and KO2 is a superoxide

② Acid oxide is not necessarily an non-metal oxide , such as Mn2O7; non-metal oxides are not necessarily an acidic oxide. , such as: CO, NO, etc.

③Acidic oxides and alkaline oxides may not necessarily react with water to form the corresponding acid and alkali. , for example: SiO2, CuO

④NO, CO is unsalt oxide . They do not react with acid or alkali

3, acid classification

4, alkali classification

5, salt classification

(1) salt concept: The cation generated during ionization of is a metal ion or (NH4+), and the anion is a compound of acid ion

(2) salt classification: salt can be divided into positive salt , acid salt , basic salt

① positive salt: The cation generated during ionization is a metal ion (NH4+), and the anion is a salt of ion. , such as : Na2SO4, NH4NO3

② Acid salt: The cation generated during ionization has H+ in addition to metal ions (NH4+), and the anion is the salt of the acid ion. such as : NaHSO4, NaHCO3

③Basic salt: The cation generated during ionization is a metal ion (NH4+). In addition to acid root, anion also has OH- salts

such as : Cu2(OH)2CO3 ( basic copper carbonate )

6, classification of compounds

4. Conversion of substances

1, chemical generalization of metals, oxides, acids, alkalis and salts

(1) Chemical generalization of metals: Take "Fe as an example"

① Metal + Oxygen -→ Metal oxide

② Metal + Acid -→Salt + Hydrogen

③ Metal + Salt -→Salt + Metal

(2) Chemical generality of oxides

① Acid oxide + Water -→ Oxygen acid

② Acid oxide + alkali -→Salt + Water

③ Acid oxide + alkali -→Salt

④ Alkaline oxide + alkaline oxide -→Salt

⑤ Alkaline oxide + acid -→ salt + water

(3) Chemical generality of acid

① Acid with acid and alkali indicator

acid encounters purple litmus turns red

② Acid + active metal -→ salt + hydrogen

③ Acid + alkali -→ salt + water

④ Acid + alkaline oxide -→ salt + water

⑤ Acid + salt -→ new acid + new salt

(4) Chemical generality of alkali

① The alkali occurs when the acid-base indicator occurs in color reaction

alkali turns red when the litmus is met, and when the phenolphthalein turns red when the

② alkali + acid oxide―→ salt + water

③ alkali + acid―→ salt + water

④ alkali + salt―→newline + new salt

(5) Chemical generality of salt

t ml0① Salt + acid -→New acid + New salt

② Salt + alkali -→New alkali + New salt

③ Salt + salt →New salt

④ Salt + metal -→Salt + metal

2, transformation relationship between elemental, oxide, acid, alkali, salt

Figure interpretation:

(1) Metal element -→Alkaline oxide, such as: 4Na + O 2===2Na2O

(2) alkaline oxide - → alkali, , for example: CaO + H2O ===Ca(OH)2

(3) metal element - → salt, , for example: Zn + H2SO4===ZnSO4 + H2↑

(4) alkaline oxide - → salt, , for example: CaO + 2HCl ===CaCl2 ＋H2O

(5)Base―→Salt, , for example: Ca(OH)2+2HCl===CaCl2+2H2O

(6) Non-metallic element―→Acidal oxide, , for example: S+O2 ignition(===Ignition===)SO2

(7)Acidic oxide―→Acidal, , for example: CO2+H2O===H2CO3

(7)Acidic oxide―→Acidal, , for example: CO2+H2O===H2CO3

(7)Acidic oxide―→Acidal, , for example: CO2+H2O===H2CO3

(8) Non-metallic element - → salt, , for example: 2Na+Cl2△(==△====)2NaCl

(9) Acid oxide - → salt, , for example: CO2+2NaOH===Na2CO3+H2O

(10) Acid - → salt, , for example: HCl+NaOH===NaCl+H2O

(10) Acid - → salt, , for example: HCl+NaOH===NaCl+H2O

5. Dispersion system

1. Definition of the system obtained by dispersing one or more substances in another or more substances is called a dispersion system.

2. The dispersed substance that constitutes

(1) is called a dispersed substance, and the substance that can disperse other substances is called dispersant ;

(2) both dispersed substance and dispersant can be in gaseous, liquid or solid state. Classification of

dispersion system

1. According to the different states of the dispersant and the dispersant, there are nine combinations between them:

2. When the dispersant is a liquid, the dispersion system can be divided into three categories according to the size of the diameter of the dispersed plasmids:

solution: the diameter of the dispersed plasmid is less than 1nm;

colloid: the diameter of the dispersed plasmid is between 1~100nm;

turbid liquid ( suspension , emulsion ): the diameter of the dispersed plasmid is greater than 100nm;

essential difference is the size of the dispersed plasmids.

3. The difference between several dispersion systems:

Colloid

1. Definition of colloid

dispersion system with diameters of dispersion plasmids between 1 and 100 nm.

2, Colloid classification

(1) Colloids can be divided into three categories according to the state of the dispersant forming the colloid: liquid sol, solid sol, and aerosol .

(2) is divided into two categories according to the different dispersible composition categories:

3, properties of colloids

(1) Medium stability

Colloids have strong stability, and the reasons are: ① The colloids in the colloids are small in diameter and are collide by medium molecules, which are not easy to float or sink; ② The colloids in the colloids carry the same charge, which repel each other, so that the colloids are not easy to accumulate and sink.

(2) Dingdal effect

When a beam of visible light passes through the colloid, a bright "path" can be seen. This bright "path" is formed by the scattering of light by colloidal particles (light waves deviate from their original direction and propagate dispersedly), which is called the Tindal effect.

Description: ① The light column seen when the beam passes through the colloid is not the colloidal particles themselves emit light, but the formation of the colloidal particles scattering the light; ② The Dindal effect is a commonly used physical method to distinguish solutions from colloids.

(3) Brownian motion

Colloidal particles perform endless and disorderly movements in the dispersed system. The generation of Brownian motion is related to the endless random impact of dispersant molecules on the colloid, and is not an inherent property of the colloid itself.

(4) Electrophoresis

Because the rubber particles carry charge, under the action of an external electric field, the rubber particles will move in a direction towards the electrode opposite to their electrical properties. This movement phenomenon is called electrophoresis. For example, the Fe(OH)₃ rubber particles are positively charged. After energizing for a period of time, the positively charged Fe(OH)₃ rubber particles move to the cathode. Note: Colloids are electrically neutral, while some colloids are charged.

For example, a large amount of smoke from a metallurgical plant can be removed by high voltage electricity, which is to use the electrophoresis of aerosols.

[Note] Since charged ions can also move in a directional direction when they are energized, electrophoresis cannot be used to distinguish solution from colloids.

(5) Colloid polysession

Under certain conditions, neutralize the charge carried by the colloid particles, and the colloid particles will aggregate into large particles, thereby forming precipitation. This property is called colloid polysession . The usual methods of accumulation and deposition include:

① Heating: When heating, the energy increases, the movement of the colloid is intensified, and the chances of collision between them increase, resulting in colloid condensation. For example, when heated for a long time, the Fe(OH)₃ colloid condenses and reddish-brown precipitate occurs.

② Add electrolyte: Add electrolyte to the solution, which increases the total concentration of ions in the colloid, and creates favorable conditions for the charged colloid particles to attract oppositely charged ions, thereby reducing or neutralizing the charges carried by the original colloid particles, causing them to lose the factor of maintaining stability. In addition, the particles are constantly doing Brownian motion, and when they collide with each other, they can gather and settle quickly.

③ Add colloids with opposite charges: If the colloids of the two colloids have opposite charges, they will neutralize charges when they meet, thereby aggregating into large particles and depositing.

4. Application of colloids

(1) Agricultural production: the fertilizer retention effect of soil; many substances in the soil, such as soil, humus, etc. often exist in colloid form.

(2) Medical and health: hemodialysis ; serum electrophoresis on paper; various amino acid and proteins are separated by electrophoresis.

(3) Daily life: tofu (colloidal accumulation); alum water purification.

(4) Natural Geography : The principle of forming a delta at the estuary of rivers is that the electrolytes in seawater cause the colloid formed by river silt to accumulate and sink.

(5) Industrial production: making non-ferrous glass (solid sol); metallurgical industry uses electrophoresis principle to dress ore; crude oil dehydration, etc.

5, Colloid purification (dialysis method)

Because the colloid particles are large in diameter and cannot pass through the semi-permeable membrane, the colloid can be purified and refined using the semi-permeable membrane. This method is called the dialysis method , and the

dialysis method is often used to separate and purify the colloid (note: the purified colloid is still a mixture).