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{{Short description|Oxide that shows basic properties}}
{{Original research|date=May 2021}}{{synthesis|date=May 2021}}
{{Acids and bases}}'''Basic oxides''' are [[oxide]]s that show [[Base (chemistry)|basic]] properties, in opposition to [[acidic oxide]]s. A basic oxide can either react with [[water]] to form a base, or with an [[acid]] to form a [[salt (chemistry)|salt]] and water in a [[Neutralization (chemistry)|neutralization reaction]]. 
Examples include:
*[[Sodium oxide]], which reacts with water to produce [[sodium hydroxide]]
*[[Magnesium oxide]], which reacts with [[hydrochloric acid]] to form [[magnesium chloride]]
*[[Copper(II) oxide]], which reacts with [[nitric acid]] to form [[copper nitrate]]

==Definition==
An oxide is a chemical compound in which one or more oxygen atoms combined with another element, such as [[H2O|H<sub>2</sub>O]] or [[CO2|CO<sub>2</sub>]]. Based on their acid-base characteristics, oxides can be classified into four categories: acidic oxides, basic oxides, and [[amphoteric]] oxides and neutral oxides.{{says who?|date=May 2021}}

A basic oxide, also called a [[base anhydride]] (meaning "base without water"), is usually formed in the reaction of oxygen with metals, especially [[alkali metals|alkali]] (group 1) and [[alkaline earth metals|alkaline earth]] (group 2) metals. Both of these groups form [[Ionic compound|ionic]] oxides that dissolve in water to form basic solutions of the corresponding [[metal hydroxide]]:  

Alkali metals (Group 1)
:X<sub>2</sub>O + H<sub>2</sub>O → 2XOH   (X = group 1 element)

Alkaline earth metals (group 2)
:XO + H<sub>2</sub>O → X(OH)<sub>2</sub>   (X = group 2 element)

For example, the basic oxide [[Lithium oxide|Li<sub>2</sub>O]] becomes the hydroxide [[Lithium hydroxide|LiOH]], and [[Barium oxide|BaO]] becomes [[Barium hydroxide|Ba(OH)<sub>2</sub>]] after reacting with water. In contrast, non-metals usually form [[acidic oxide]]s. In general, the basicity of oxides increases when towards the lower-left corner of the [[periodic table]], which corresponds to increased metallic properties.<ref>{{Cite book|last=Dr.Verma, Khanna, Dr.Kapila|title=Comprehensive Chemistry XI|publisher=Laxmi Publications|year=2017|pages=164}}</ref>

==Examples==
*All oxides of group 1 & 2 elements are basic (except BeO), they react with [[water]] to form a [[Base (chemistry)|base]]:<ref>{{Cite book |last=Atkins |first=P. |title=Inorganic Chemistry |last2=Overton |first2=T. |last3=Rourke |first3=J. |last4=Weller |first4=M. |last5=Armstrong |first5=F. |publisher=Oxford University Press |year=2006 |pages=264, 278}}</ref>
** [[Lithium oxide]] reacts with water to produce [[lithium hydroxide]]: Li<sub>2</sub>O + H<sub>2</sub>O → 2 LiOH
** [[Sodium oxide]] reacts with water to produce [[sodium hydroxide]]: Na<sub>2</sub>O + H<sub>2</sub>O  → 2 NaOH
** [[Potassium oxide]] reacts with water to produce [[potassium hydroxide]]: K<sub>2</sub>O  + H<sub>2</sub>O  → 2 KOH 
** [[Rubidium oxide]] reacts with water to produce [[rubidium hydroxide]]: Rb<sub>2</sub>O  + H<sub>2</sub>O  → 2 RbOH 
** [[Caesium oxide]] reacts with water to produce [[caesium hydroxide]]: Cs<sub>2</sub>O  + H<sub>2</sub>O  → 2 CsOH 
** [[Magnesium oxide]] reacts with water to produce [[magnesium hydroxide]]: MgO  + H<sub>2</sub>O  → Mg(OH)<sub>2</sub> 
** [[Calcium oxide]] reacts with water to produce [[calcium hydroxide]]: CaO  + H<sub>2</sub>O  → Ca(OH)<sub>2</sub> 
** [[Strontium oxide]] reacts with water to produce [[strontium hydroxide]]: SrO  + H<sub>2</sub>O  → Sr(OH)<sub>2</sub> 
** [[Barium oxide]] reacts with water to produce [[barium hydroxide]]: BaO  + H<sub>2</sub>O  → Ba(OH)<sub>2</sub> 
** [[Radium oxide]] reacts with water to produce [[radium hydroxide]]: RaO  + H<sub>2</sub>O  → Ra(OH)<sub>2</sub> 
*Some oxides of other main group elements are basic, reacting with [[water]] to form a [[Base (chemistry)|base]]:
** [[Thallium(I) oxide]], a group 13 oxide, reacts with water to produce [[thallium(I) hydroxide]]: Tl<sub>2</sub>O  + H<sub>2</sub>O  → 2 TlOH
** [[Bismuth(III) oxide]], a group 15 oxide, reacts with water to produce [[Bismuth hydroxide|bismuth(III) hydroxide]]: Bi<sub>2</sub>O<sub>3</sub>  + 3H<sub>2</sub>O  → 2 Bi(OH)<sub>3</sub> 
* In [[Neutralization (chemistry)|neutralization reactions]], basic oxides reacts with an [[acid]] to form [[salt]] and [[water]]:
** [[Magnesium oxide]] reacts with [[hydrogen chloride]] (acid) to produce [[magnesium chloride]] (salt) and water: MgO + 2 HCl → MgCl<sub>2</sub> + H<sub>2</sub>O
** [[Sodium oxide]] reacts with [[hydrogen chloride]] (acid) to produce [[sodium chloride]] (salt) and water: Na<sub>2</sub>O + 2 HCl → 2 NaCl + H<sub>2</sub>O

<gallery>
File:Magnesium oxide.jpg|Magnesium oxide
File:Calcium oxide powder.JPG|Calcium oxide
</gallery>

==See also==
{{Commons category|Basic oxides}}
*[[Acidic oxide]]
*[[Amphoterism#Amphoteric oxides|Amphoteric oxide]]

== References ==
<references/>

{{DEFAULTSORT:Basic Oxide}}
[[Category:Oxides]]