Editing Lead(II) oxide (section)

==Structure==
As determined by [[X-ray crystallography]], both polymorphs, [[tetragonal]] and [[orthorhombic]] feature a pyramidal four-coordinate lead center. In the tetragonal form the four lead–oxygen bonds have the same length, but in the orthorhombic two are shorter and two longer. The pyramidal nature indicates the presence of a [[stereochemistry|stereochemically]] active [[lone pair]] of electrons.<ref>{{Wells5th}}{{page needed|date=June 2017}}</ref> When PbO occurs in tetragonal lattice structure it is called [[litharge]]; and when the PbO has orthorhombic lattice structure it is called [[massicot]]. The PbO can be changed from massicot to litharge or vice versa by controlled heating and cooling.<ref>A simple example is given in {{cite book |author=Anil Kumar De |title=A Textbook Of Inorganic Chemistry |chapter-url=https://books.google.com/books?id=PpTi_JAx7PgC&pg=PA383 |year=2007 |publisher=New Age International |isbn=978-81-224-1384-7 |pages=383 |chapter=§9.2.6 Lead (Pb): Lead Monoxide PbO }} A more complex example is in {{cite book |first=N.Y. |last=Turova |title=The Chemistry of Metal Alkoxides |chapter-url=https://books.google.com/books?id=rPzaMRjK8pQC&pg=PA115 |date=2002 |publisher=Springer |isbn=978-0-7923-7521-0 |pages=115 |chapter=§9.4 Germanium, tin, lead alkoxides}}</ref> The tetragonal form is usually red or orange color, while the orthorhombic is usually yellow or orange, but the color is not a very reliable indicator of the structure.<ref>{{cite book |first=David John |last=Rowe |title=Lead Manufacturing in Britain: A History |url=https://books.google.com/books?id=ZL4OAAAAQAAJ&pg=PA16 |date=1983 |publisher=Croom Helm |isbn=978-0-7099-2250-6 |pages=16}}</ref> The tetragonal and orthorhombic [[Polymorphism (materials science)|forms]] of PbO occur naturally as rare minerals.

{{gallery|mode=packed-hover
|title=Crystal structure in litharge form<ref name="G&E" /><ref>{{ cite journal | doi = 10.1016/S0167-2738(01)00699-3 | journal = [[Solid State Ionics|Solid State Ion.]] | year = 2001 | volume = 140 | pages = 115–123 | first1 = Caroline | last1 = Pirovano | first2 = M. Saiful | last2 = Islam | authorlink2 = Saiful Islam (professor) | first3 = Rose-Noëlle | last3 = Vannier | first4 = Guy | last4 = Nowogrocki | first5 = Gaëtan | last5 = Mairesse | title = Modelling the crystal structures of Aurivillius phases | issue = 1–2 }}</ref><ref>{{ cite web | url = https://www.ccdc.cam.ac.uk/structures/Search?Ccdcid=1653774&DatabaseToSearch=Published | title = ICSD Entry: 94333 | author = <!--Not stated--> | website = [[Cambridge Structural Database]]: Access Structures | publisher = [[Cambridge Crystallographic Data Centre]] | access-date = 2021-06-01 }}</ref>
|File:PbO-litharge-xtal-Pb-coordination-3D-bs-17.png|Pb coordinates [[square pyramidal molecular geometry|square-pyramidally]]
|File:PbO-litharge-xtal-O-coordination-3D-bs-17.png|O coordinates distorted-[[Tetrahedral molecular geometry|tetrahedrally]]
|File:PbO-litharge-xtal-unit-cell-3D-bs-17.png|Unit cell
|File:PbO-litharge-xtal-3x3x3-3D-bs-17.png|{{math|3×3×3}} unit cells
|File:PbO-litharge-xtal-3x3x3-a-3D-bs-17.png|Along the [[Lattice parameters|{{mvar|a}} axis]]
|File:PbO-litharge-xtal-3x3x3-c-3D-bs-17.png|Along the [[Lattice parameters|{{mvar|c}} axis]]
}}