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Trigonal pyramid (chemistry)

 

 
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Trigonal pyramid (chemistry)
 
 
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In chemistry
Chemistry

Chemistry is the science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions....
, a trigonal pyramid is a molecular geometry
Molecular geometry

Molecular geometry or molecular structure is the three-dimensional arrangement of the atoms that constitute a molecule. It determines several properties of a substance including its Reactivity , Chemical polarity, Phase , color, magnetism, and biological activity....
 with one atom at the apex
Apex

Apex may refer to:...
 and three atoms at the corners of a trigonal base. When all three atoms at the corners are identical, the molecule belongs to point group
Molecular symmetry

Molecular symmetry in chemistry describes the symmetry present in molecules and the classification of molecules according to their symmetry. Molecular symmetry is a fundamental concept in chemistry, as it can predict or explain many of a molecule's chemical property, such as its molecular dipole moment and its allowed spectroscopy ....
 C3v. One example of a molecule
Molecule

In chemistry, a molecule is defined as a sufficiently stable, electric charge neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds....
 with a trigonal pyramidal geometry is ammonia
Ammonia

Ammonia is a chemical compound with the chemical formula nitrogenhydrogen. It is normally encountered as a gas with a characteristic pungent odor....
 (NH3). Some molecules and ions with trigonal pyramidal geometry include the xenon trioxide
Xenon trioxide

Xenon trioxide is an unstable compound of xenon in its +6 oxidation state. It is a very powerful oxidizing agent, and liberates oxygen from water slowly, accelerated by exposure to sunlight....
 molecule, XeO3, the chlorate
Chlorate

The chlorate anion has the formula ClO3-. In this case, the chlorine atom is in the +5 oxidation state. "Chlorate" can also refer to chemical compounds containing this anion; Chlorate#Compounds are the salt s of chloric acid....
 ion, ClO3-, the sulfite
Sulfite

Sulfites are chemical compound that contain the sulfite ion sulfuroxygen32- ....
 ion, SO32-, and the phosphite
Phosphite

The phosphite ion is a polyatomic ion with a phosphorus central atom where phosphorus has an oxidation state of +3. Its geometry is approximately tetrahedral.The bonding can be described in terms of a number of resonance canonicals, effectively delocalising the negative charges across the three equivalent oxygen atoms.Many phosphite salts, s...
 ion, PO33-.






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In chemistry
Chemistry

Chemistry is the science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions....
, a trigonal pyramid is a molecular geometry
Molecular geometry

Molecular geometry or molecular structure is the three-dimensional arrangement of the atoms that constitute a molecule. It determines several properties of a substance including its Reactivity , Chemical polarity, Phase , color, magnetism, and biological activity....
 with one atom at the apex
Apex

Apex may refer to:...
 and three atoms at the corners of a trigonal base. When all three atoms at the corners are identical, the molecule belongs to point group
Molecular symmetry

Molecular symmetry in chemistry describes the symmetry present in molecules and the classification of molecules according to their symmetry. Molecular symmetry is a fundamental concept in chemistry, as it can predict or explain many of a molecule's chemical property, such as its molecular dipole moment and its allowed spectroscopy ....
 C3v. One example of a molecule
Molecule

In chemistry, a molecule is defined as a sufficiently stable, electric charge neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds....
 with a trigonal pyramidal geometry is ammonia
Ammonia

Ammonia is a chemical compound with the chemical formula nitrogenhydrogen. It is normally encountered as a gas with a characteristic pungent odor....
 (NH3). Some molecules and ions with trigonal pyramidal geometry include the xenon trioxide
Xenon trioxide

Xenon trioxide is an unstable compound of xenon in its +6 oxidation state. It is a very powerful oxidizing agent, and liberates oxygen from water slowly, accelerated by exposure to sunlight....
 molecule, XeO3, the chlorate
Chlorate

The chlorate anion has the formula ClO3-. In this case, the chlorine atom is in the +5 oxidation state. "Chlorate" can also refer to chemical compounds containing this anion; Chlorate#Compounds are the salt s of chloric acid....
 ion, ClO3-, the sulfite
Sulfite

Sulfites are chemical compound that contain the sulfite ion sulfuroxygen32- ....
 ion, SO32-, and the phosphite
Phosphite

The phosphite ion is a polyatomic ion with a phosphorus central atom where phosphorus has an oxidation state of +3. Its geometry is approximately tetrahedral.The bonding can be described in terms of a number of resonance canonicals, effectively delocalising the negative charges across the three equivalent oxygen atoms.Many phosphite salts, s...
 ion, PO33-. In organic chemistry, molecules which have a trigonal pyramidal geometry are sometimes described as sp3 hybridized
Orbital hybridisation

In chemistry, hybridisation or hybridization is the concept of mixing atomic orbitals to form new hybrid orbitals suitable for the qualitative description of atomic bonding properties....
. The AXE method for VSEPR theory states that the classification is AX3E.

Trigonal pyramidal geometry in ammonia

The nitrogen
Nitrogen

Nitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674?. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere....
 atom in ammonia
Ammonia

Ammonia is a chemical compound with the chemical formula nitrogenhydrogen. It is normally encountered as a gas with a characteristic pungent odor....
 has 5 valence electron
Valence electron

In science, valence electrons are the electrons contained in the outermost, or valence, electron shell of an atom. Valence electrons are important in determining how an chemical element reacts chemically with other elements: The fewer valence electrons an atom holds, the less reactivity it becomes and the more likely it is to chemical rea...
s and bonds with three hydrogen atoms to complete the octet
Octet rule

The octet rule is a simple chemistry rule of thumb that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells, giving them the same electronic configuration as a noble gas....
. This would result in the geometry of a regular tetrahedron
Tetrahedron

A tetrahedron is a polyhedron composed of four triangle faces, three of which meet at each vertex . A regular tetrahedron is one in which the four triangles are regular, or "equilateral", and is one of the Platonic solids....
 with each bond angle cos-1(-?)
Inverse trigonometric function

In mathematics, the inverse trigonometric functions or cyclometric functions are the inverse functions of the trigonometric functions. The principal inverses are listed in the following table....
 ˜ 109.5°. However, the three hydrogen atoms are repelled by the electron lone pair
Lone pair

A lone pair is a valence electron pair without bonding or sharing with other atoms. They are found in the outermost electron shell of an atom, so lone pairs are a subset of a molecule's valence electrons....
 in a way that the geometry is distorted to a trigonal pyramid
Pyramid

A pyramid is a building where the outer surfaces are triangular and converge at a point. The base of pyramids are usually quadrilateral or trilateral , meaning that a pyramid usually has four or five faces....
 (regular 3-sided pyramid) with bond angles of 107°. In contrast, boron trifluoride
Boron trifluoride

Boron trifluoride is the chemical compound with the chemical formula BF3. This pungent colourless toxic gas forms white fumes in moist air....
 is flat, adopting a trigonal planar
Trigonal planar

In chemistry, trigonal planar is a molecular geometry with one atom at the center and three atoms at the corners of a triangle all in one plane ....
 geometry because the boron
Boron

Boron is a chemical element with atomic number 5 and the chemical symbol B. Boron is a trivalent metalloid element which occurs abundantly in the evaporite ores borax and ulexite....
 does not have a lone pair of electrons.

In ammonia the trigonal pyramid undergoes rapid nitrogen inversion
Nitrogen inversion

In chemistry, a nitrogen compound like ammonia in a trigonal Pyramid geometry undergoes rapid nitrogen inversion whereby the molecule turns inside out....
.

See also

  • AXE method
  • Molecular geometry
    Molecular geometry

    Molecular geometry or molecular structure is the three-dimensional arrangement of the atoms that constitute a molecule. It determines several properties of a substance including its Reactivity , Chemical polarity, Phase , color, magnetism, and biological activity....


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