oxide

[yǎng huà wù]

chemical compound

Collection

zero Useful+1

zero

This entry is made by Compilation and application of scientific encyclopedia entries of "Science Popularization China" to examine.

Oxide belongs to chemical compound (Of course, it must be Pure substance ）。 Its composition contains only two elements, one of which must be oxygen, and the other, if it is metal, is called metallic oxide ； If the other is not metallic element , it is called Nonmetallic oxide 。^[1]

generalized The oxide on refers to Oxygen element Composed of another chemical element Binary compound , such as carbon dioxide （CO₂）、 calcium oxide （CaO）、 carbon monoxide (CO), etc. However, the compounds formed by the combination of oxygen and fluorine with greater electronegativity are generally called fluorides rather than oxides.

Chinese name: oxide
Foreign name: oxide^[5]

Composition: Oxygen element With another chemical element
Classification: Acidic, alkaline, amphoteric, neutral oxides, etc

catalog

Acid oxide

Announce

edit

Before we talk about concepts, let's look at the following two examples:

2NaOH+CO two =Na two CO three +H two O

Ca(OH) two +SO three =CaSO four +H two O

The above reaction shows that: carbon dioxide The nature of sulfur trioxide is similar to that of acid. Therefore, people call carbon dioxide and sulfur trioxide, which can react with alkali to form only salt and water oxides Acid oxide 。

Nonmetallic oxide Most are acid oxides, such as carbon dioxide sulfur dioxide Etc.

However, acid oxides are not necessarily non-metallic oxides.

React with water

Most acid oxides can directly combine with water to form acids.

CO two +H two O=H two CO three

SO three +H two O=H two SO four

SiO two Can not react directly with water to generate H two SiO three 。

Unstable acid can also be generated by thermal decomposition Acid oxide 。

H two CO three =(Heating) CO 2↑ +H two O

H two SO four =SO three ↑+H two O

ad locum carbon dioxide Sulfur trioxide can be regarded as the product of dehydration of carbonic acid and sulfuric acid, called Acid anhydride 。

It can be said that all acid oxides are anhydride.

Reaction with alkali

Acid oxides can react with alkali to form salt and water.

2NaOH+CO two =Na two CO three +H two O

Ca(OH) two +SO three =CaSO four +H two O

And alkaline oxides

Under certain conditions, Alkaline oxide React with acid oxides to form salts.

CaO+CO two =CaCO three

CaO+SiO two =(High temperature) CaSiO three^[2]

Alkaline oxide

Announce

edit

For the same introduction, let's look at the following two examples:

2HCl+CuO=CuCl two +H2O

3H two SO four +Fe two O three =Fe two (SO four ) three +3H two O

The above reaction shows that the properties of copper oxide, iron oxide and alkali are similar. Therefore, people call copper oxide and iron oxide, which can react with acid to form only salt and water oxides Alkaline oxide 。（SiO two It can react with HF, but SiO two yes Acid oxide （SiO two Can react with HF is SiO two Is independent of whether it is alkaline oxide or acidic oxide) metallic oxide And other low valent oxides of metals, such as Na two O. CaO, BaO, CrO, MnO, etc.)

Most metal oxides are Alkaline oxide , but there are some other types, with the exception of Mn two O seven （ Acid oxide ），Al two O three （ Amphoteric oxide ）, ZnO (amphoteric oxide), MnO two (amphoteric oxide), etc.

Although acid oxides are not necessarily Nonmetallic oxide (e.g. Mn two O seven ）However, we can say that the alkaline oxide must be a metal oxide.

React with water

The corresponding hydrate of alkaline oxide is alkali, and the corresponding alkali is Soluble alkali The alkaline oxide of C can be directly combined with water to form a base.

K two O+H two O=2KOH

Na two O+H two O=2NaOH

BaO+H two O=Ba(OH) two

CaO+H two O=Ca(OH) two

Theoretically, Alkaline oxide It can be regarded as the product of corresponding alkali dehydration.

Insoluble alkali can be decomposed by heat to produce corresponding alkaline oxide and water.

Cu(OH) two =(Heating) CuO+H two O

React with acid

Alkaline oxides can react with acids to form salts and water.

2HCl+CuO=CuCl two +H2O

3H two SO four +Fe two O three =Fe two (SO four ) three +3H two O

Reaction with salt

Alkaline oxides generally do not Orthosalt 、 Basic salt Reaction, but can be connected with Acid salt Reaction.

Na two O+2NaHSO four =2Na two SO four +H two O^[2]

Amphoteric oxide

Announce

edit

Because it is a critical element Metallicity , there are certain Nonmetallic , while being able to Strong acid and strong base The reaction is called amphoteric, and the corresponding hydrates are also Amphoteric hydroxide 。

As Al two O three , ZnO, etc.

With Al two O three For example:

Al two O three + 6HCl= 2AlCl three + 3H two O

Al two O three + 2NaOH = 2NaAlO two + H two O^[2]

MnO two Same Amphoteric oxide 。 Moderate oxidation in acid medium, 2MnO two +2H two SO four =2MnSO four +O two +2H two O。 It has medium strength reducibility in strong alkali and can be oxidized by oxygen in air to produce MnO four 。

Mn two O seven >MnO three >MnO two >MnO

Acidic Acidic Amphoteric Alkaline

Neutral oxide

Announce

edit

Oxides that cannot react with acid to form salt and water and cannot react with alkali to form salt and water are called Neutral oxide perhaps Unsalted oxide 。

As H two O、NO、N two O. CO belongs to Neutral oxide / Unsalted oxide 。

Nitrogen dioxide It is an unsalted oxide because the valence in the oxyacid of nitrogen is not+4. (The oxide corresponding to nitrate is Nitrogen pentoxide It is not nitrogen dioxide, or the anhydride of nitric acid is nitrogen pentoxide instead of nitrogen dioxide.)

It should be noted here that some non salt forming oxides can "form salt" under certain conditions.

although carbon monoxide Can follow sodium hydroxide React to form sodium salt of formic acid. However, no water is generated when salt is generated, so carbon monoxide still belongs to non salt oxide.^[2]

peroxide

Announce

edit

Sodium peroxide peroxide , because the molecule contains Peroxy group or Peroxy ion And get its name. In addition, it has extremely weak acidic hydrogen peroxide Peroxides can also be formed by reacting with alkali. Therefore, peroxide can also be regarded as a salt of hydrogen peroxide. Metal that can generate peroxide, mainly alkali metal and alkaline-earth metal 。

Sodium peroxide Sodium peroxide is one of the products of sodium combustion in oxygen or air. Pure sodium peroxide is white, but generally seen sodium peroxide is light yellow, because a small amount of sodium peroxide is generated during the reaction Sodium Superoxide 。 Sodium peroxide is easy to Deliquescence , Yes corrosive , should be sealed for storage; With strong Oxidizability , can be used to bleach Textile articles, straw, feathers, etc.^[3]

Structure classification

Announce

edit

Ionic type

Type of chemical formula	Examples of oxides
M two O	alkali metal Oxide of
MO	BeO、MgO、CaO、SrO、BaO、CdO、VO、MnO、CoO、NiO
M two O three	Al two O three 、Sc two O three 、Ln two O three ( Lanthanide metal Oxide)
MO three	ReO3、WO three
M three O four	Fe three O four 、Pb three O four 、Mn three O four

covalent

structure type		Examples of oxides
Nonmetallic element	Simple molecular oxide	H. Oxides of F, Cl, Br, I, S, Se, N, P, As, C
	Macromolecular oxide	B. Oxide of Si
metallic element	18 Oxide of electronic housing ion	Ag two O、Cu two O
	18+2 oxide of electronic housing ion	SnO、PbO
	8 Electronic housing, oxide of highly charged ions	Mn two O seven^[4]

chemical property

Announce

edit

Acid-base property

According to the acid-base characteristics, oxides can be divided into four categories: acidic, alkaline, amphoteric and neutral.

（1） Acid oxide 。 Oxides that dissolve in water as acid solutions or occur with the same alkali are acid oxides. For example:

P four O ten +6H two O→4H three PO four

Sb two O five +2NaOH+5H two O→2Na[Sb(OH) six ]

Most non-metallic covalent oxides and some highly oxidized metal oxides with weak electropositivity are acidic.

（2） Alkaline oxide 。 The oxides dissolved in water as alkaline solution or occurring with acid are alkaline oxides. For example:

CaO+H two O→Ca(OH) two

Fe two O three +6HCl→2FeCl three +3H two O

The oxides of most electropositive elements are alkaline.

（3） Amphoteric oxide 。 The oxides that are alkaline and acidic with strong acid are amphoteric oxides. For example:

ZnO+2HCl→ZnCl two +H2O

ZnO+2NaOH+H two O→Na two [Zn(OH) four ]

The oxides of some metal elements close to the non-metallic region in the long-period table are easy to show hermaphroditism.

（4） Neutral oxide 。 Oxides that do not react with acids or bases are called neutral oxides. E.g. CO and N two O。

See: Acidity and alkalinity of oxides 。

thermal stability

Most oxides have high thermal stability , especially oxides and Li of IIA and IVB group elements two O、Na two O、B two O three 、Al two O3、SiO two Less oxide with thermal instability, such as halogen Oxide, N two O five 、A g2 O. HgO, etc. Short period element Oxide stability Decreasing from left to right , alkali only metal element oxides are more stable alkaline-earth metal For poor, when we consider M + The repulsion between ions makes M two When the lattice energy of O is low, it is not difficult to understand this "abnormal" phenomenon; In the same family, especially Subfamily elements , thermal stability is enhanced from top to bottom , this is because, although cation And the sum of anion radius Lattice energy , but with Atomic radius The effect of increasing the ionization energy is more significant, especially when the cation Radius ratio This is especially true when the radius of the oxygen ion is small.

Classification summary

Announce

edit

① It can be divided into metal oxides and Nonmetallic oxide

② It can be divided into ionic oxide and covalent oxide according to bonding type or constituent particle type

Ionic oxide: oxides formed by some active metal elements, such as Na2O, CaO, etc

Covalent oxides: oxides of some metallic elements and all non-metallic elements, such as MnO2, HgO, SO2, ClO2, etc

③ According to the oxidation state of oxygen, it can be divided into ordinary oxides (the oxidation state of oxygen is - 2), peroxides (the oxidation state of oxygen is - 1) Superoxide (The oxidation state of oxygen is - 1/2) and ozone (the oxidation state of oxygen is - 1/3)

④ According to the acidity and alkalinity, whether it forms salt with water, and the salt content generated Acid oxide , alkaline oxides and amphoteric oxides Neutral oxide 、 Complex oxide 。

Novice on the road

Growth task Getting Started with Editing Edit Rule Edit by myself

I have questions

Content query Online Service Official post bar Feedback

Complaints and suggestions

Report bad information Failed to appeal through entries Complaint of infringement information Blocking query and unblocking

Jinggong Network Anbei No. 1100000200001