Why are there no metallic elements in acids?

Metaaluminic acid dichromatic acid is more, and it is generally no different.

There are also metaaluminic acid, etc., these metals are not very metallic, and these knowledge can be learned at a high level.

There are also high iron acid H2FeO4, permanganate KMNO4, manganese acid K2MNO4, dichromatic acid H2Cr2O6 ......Many, but generally unstable, with strong reduction.

In general, the metallicity of metals that can form acids is not very strong, nor is it very weak.

The current special acid theory requires that acid must be a cation, and can only be called acid if it is ionized by protons, and the general metal elements will be directly ionized in the chemical state, which does not meet the definition of acid, For polyacids, the valence electrons (outermost electrons) of metals are generally few, and they cannot form multiple covalent bonds, so they naturally cannot form polyacids, manganese is more special, and there is iron, such as iron acid, but it is unstable, and permanganic acid is also They are excessive elements, and some properties will have some qualitative changes, which is also expected, This is just the limitation of our use of acid theory There are many other different acid theories that don't have this law.

Let's analyze it from an oxide perspective.

In general, the oxides of metals with strong metallicity and the low-valent oxides of transition metals (such as oxides of metals such as Nakca, Mn0, Fe203, etc.) are ionic crystals, and the polarization of these metals is weak, and the negative potential of O2- (simply put, the ability to grab electrons) is very high, and there is a strong tendency to bind hydrogen ions from water to become hydroxides and are strongly alkaline

02- +h20 == 2oh-

However, when the transition metal is in the ** state, its oxide is acidic, because at this time, the polarization of the ** transition metal is strong. Covalent bonds with O2- ions These oxides react with water to form acids:

cr03 + h20 == cr042- +2h+

mno7 + h2o == 2mno4- +2h+

FeO3 (high iron oxide) H20 == Fe042- +H+

There are also metals at the junction of metals and non-metals, such as AL, which have Al(OH)3 and H3AL03 (aluminic acid, uncommon, often dehydrated into metaaluminic acid halo2) (that is, its oxide is both acid and alkali).

You should know that the solution is alkaline when hydrolyzed to OH-, and the solution becomes acidic when hydrolyzed to H+.

The difference between the metal element that can form acid and other general metals is that its valency in the compound must be higher; Or it is at the junction of metal and non-metal.

The acids that have metal elements in inorganic acids are mainly as follows:

1.Amphoteric metal oxides corresponding to hydrates (metal hydroxides), such as aluminic acid (= aluminum hydroxide; Metaaluminic acid does not actually exist, the metaaluminate present in aqueous solution is [Al(OH)4]- hence LS error), zinc acid, stantinic acid, etc. There are two ionization methods for this kind of substance, when it reacts with acid, ionized metal cations and OH- are dominant, and they are alkaline; It reacts with a strong base to ionize metallic acid and H+, which is mainly acidic.

2.Hydrates corresponding to ** oxides in transition metals, such as permanganese acid, dichromatic acid, high iron acid, etc. This type of acid is strongly oxidizing and unstable.

These acids are rarely found in the form of acids, but in the form of corresponding salts.

Look at what is sour.

1.Concentrated sulfuric acid, Songli concentrated nitric acid reacts with metals to reflect oxidation and acidity.

2. The reaction between dilute sulfuric acid and metal reflects acidity.

3. Dilute nitric acid (general) reacts with metals to reflect oxygen leakage and acidity. It is closely related to concentration.

4. The reaction between weak acid and metal reflects acidity.

The common ones are permanganate-hmno4, and the familiar salt potassium permanganate-kmno4.

Metaaluminic acid, halo , the familiar salt sodium metaaluminate naalo .

Dichromate H2Cr2O7 , the familiar salt potassium dichromate K2Cr2O7 .

Ferrate H2FeO4 , the familiar salt sodium ferrate Na2FeO4

Understand according to the definition of acid and base in secondary school.

Most acids are non-metallic oxides, which are obtained by reacting with hydrogen, and a few hydrochloric acids and other elements do not contain oxygen.

Most alkalis are obtained by the synthesis of metal oxides and hydroxide groups of water, so most of them have metal elements, but ammonia and other special ones have no metal elements.

All exceptions are made.