Gyroelongated square pyramid

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Gyroelongated square pyramid
Gyroelongated square pyramid.png
Type Johnson
J9J10J11
Faces 12 triangles
1 square
Edges 20
Vertices 9
Vertex configuration
Symmetry group
Properties convex, composite
Net
Johnson solid 10 net.png

In geometry, the gyroelongated square pyramid is the Johnson solid that can be constructed by attaching an equilateral square pyramid to a square antiprism. It occurs in chemistry; for example, the capped square antiprismatic molecular geometry.

Contents

Construction

The gyroelongated square pyramid is composite, since it can be constructed by attaching one equilateral square pyramid to the square antiprism, a process known as gyroelongation. [1] [2] This construction involves the covering of one of two square faces and replacing them with the four equilateral triangles, so that the resulting polyhedron has twelve equilateral triangles and one square. [3] Any convex polyhedron in which all of the faces are regular is a Johnson solid, and the gyroelongated square pyramid is one of them, enumerated as , the tenth Johnson solid. [4]

Properties

The surface area of a gyroelongated square pyramid with edge length is: [3] the area of twelve equilateral triangles and a square. Its volume: [3] can be obtained by slicing the square pyramid and the square antiprism, after which adding their volumes. [3]

3D model of a gyroelongated square pyramid J10 gyroelongated square pyramid.stl
3D model of a gyroelongated square pyramid

It has the same three-dimensional symmetry group as the square pyramid, the cyclic group of order eight. Its dihedral angle can be derived by calculating the angle of a square pyramid and square antiprism in the following: [5]

Applications

In stereochemistry, the capped square antiprismatic molecular geometry can be described as the atom cluster of the gyroelongated square pyramid. An example is [LaCl(H
2
O)
7
]4+
2
, a lanthanum(III) complex with a La–La bond. [6]

References

  1. Timofeenko, A. V. (2010). "Junction of Non-composite Polyhedra" (PDF). St. Petersburg Mathematical Journal. 21 (3): 483–512. doi:10.1090/S1061-0022-10-01105-2.
  2. Rajwade, A. R. (2001). Convex Polyhedra with Regularity Conditions and Hilbert's Third Problem. Texts and Readings in Mathematics. Hindustan Book Agency. doi:10.1007/978-93-86279-06-4. ISBN   978-93-86279-06-4.
  3. 1 2 3 4 Berman, Martin (1971). "Regular-faced convex polyhedra". Journal of the Franklin Institute. 291 (5): 329–352. doi:10.1016/0016-0032(71)90071-8. MR   0290245.
  4. Uehara, Ryuhei (2020). Introduction to Computational Origami: The World of New Computational Geometry. Springer. p. 62. doi:10.1007/978-981-15-4470-5. ISBN   978-981-15-4470-5. S2CID   220150682.
  5. Johnson, Norman W. (1966). "Convex polyhedra with regular faces". Canadian Journal of Mathematics . 18: 169–200. doi: 10.4153/cjm-1966-021-8 . MR   0185507. S2CID   122006114. Zbl   0132.14603.
  6. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 917. ISBN   978-0-08-037941-8.

See also