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Acid-Base Character of Oxides & Hydroxides

From left to right on the periodic table, acid-base character of oxides and hydroxides go from basic to acidic.

  • Increasing charge on an anion increases the production of basic solutions.
  • As electronegativity increase, production of ionic cations increases because elements are more able to adopt a cation.
  • As ionization energy increases, the acidic nature increases.

Metallic Oxides:

- Ionic Bonding: no distribution of electron wave function

- Ionic oxides are usually basic (element act as a base when reacting with H2O)

Na2O(s) + H2O(l) --> 2NaOH(aq) --> 2Na+(aq) + 2OH-(aq)


B. Oxide B. Hydroxide

Semimetal Oxides:

- Semimetal are amphoteric (elements acts as an acid and/or base when reacting depending on pH of solution)

Al2O3 --> Al(OH)3 --(3H+)--> [Al(H2O)6]^(3+) (aq)


--(OH-)--> [Al(OH)4]-(aq)

Non-Metal Oxides

- Covalent Bonding: almost complete distribution of electron wave function

- Covalent oxides are usually acidic (elements act as an acid when reacts with H2O)

SO3 + H2O(l) -> H2SO4(aq) -> H+ + HSO4-


A. Oxide A Hydroxide

Ionic Hydrides

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Types of Hydrides

- Ionic Bonding: no distribution of electron wave function

- Bronsted Basic because they will react with proton

- Lewis Basic because they can be ligands

CaH2 + 2H2O -> 2H2 + Ca(OH)2


H- H+ H2


-In this case, CaH2 is basic because it reacts with water (an acid in this case) to form many hydrides by reducing a proton.

Covalent Hydrides

- Covalent Bonding: almost complete distribution of electron wave function

HF + H2O -> F- + H3O+ ....can also be written as HF(aq) <--> H+(aq) + F-(aq)

H+ H+ H+

- HF is a weak acid that is bronsted acid because it will loose a proton. Therefore, HF is the weak acid, where the water acts as a silent water, and F- is the weak conjugate base.

 

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