a) only bonding electron pairs are able to determine the geometry of a molecule.
b) the pairs of electrons around a central atom of a molecule behave like electronic clouds and repel each other.
c) Molecular geometry is the result of the attraction of the central atom of a molecule by nonbonding electrons.
d) the greater the number of central atoms in a molecule, the structure can assume different geometries.
The valence shell electron pair repulsion theory is a model used to predict the geometry of a molecule.
The central atom of a molecule has pairs of electrons that may or may not be participating in bonds. These valence electrons behave like electronic clouds and repel each other and orient themselves forming the greatest possible distance.
If element X with atomic number 1 forms a chemical bond with element Y with atomic number 9. What is the molecular geometry of the compound formed?
All diatomic molecules, that is, formed by only two atoms, have a linear geometry.
The element with atomic number 1 is hydrogen (H) and the element with atomic number 9 is fluorine (F), which are linked by a covalent bond and form hydrofluoric acid (HF).
Oxygen is the most abundant element on planet Earth. It is in the composition of two molecules essential for the survival of living beings: oxygen gas (O2) and water (H2O).
a) WRONG. Despite having only the chemical element oxygen, oxygen gas is a diatomic molecule, as it is formed by 2 atoms of the element. The water molecule is composed of two hydrogen atoms and one oxygen atom and is therefore triatomic.
b) WRONG. Oxygen gas is a linear molecule as it is made up of 2 atoms. The water molecule is angular, because the central atom, oxygen, in addition to making two covalent bonds, has two available pairs of electrons.
c) CORRECT. The oxygen atom is the central atom of the water molecule. Oxygen gas has two atoms linked by a covalent bond.
d) WRONG. The bond angle of the oxygen gas molecule is 180° because it is linear. The water molecule has an angle of 104.5º.
Correctly relate the molecule in column I with its respective geometry in column II.
HCN: linear geometry
Molecules with three atoms, whose central atom is bonded to two other atoms and does not contain a pair of available paired electrons, have linear geometry.
NOCl: angular geometry
Molecules with three atoms, whose central atom is bonded to two other atoms and contains a pair of available paired electrons, exhibit angular geometry.
ONLY3: planar trigonal geometry
Molecules with four atoms, whose central atom is bonded to three other atoms and does not contain a pair of available paired electrons, have planar trigonal geometry.
NH3: pyramidal geometry
Molecules with four atoms, whose central atom is bonded to three other atoms and contains a pair of available paired electrons, have pyramidal geometry.
CH4: tetrahedral geometry
Molecules with five atoms, whose central atom is bonded to four other atoms and does not contain a pair of available paired electrons, have a tetrahedral geometry.
PCl5: bipyramidal geometry
Molecules with six atoms, whose central atom is connected to five other atoms, have a bipyramidal geometry, independent of the central atom.
SF6: octahedral geometry
Molecules with seven atoms, whose central atom is connected to six other atoms, have octahedral geometry, independent of the central atom.
The greater the number of atoms in a molecule, the greater the number of possible molecular geometries. In the case of triatomic molecules, they can have linear or angular geometry.
The following are examples of molecules with available pairs of electrons on the central atom that give the angular geometry of the molecule, EXCEPT:
The carbon dioxide molecule (CO2) presents a linear geometry, since carbon, which is the central atom, does not have a pair of paired electrons available. The angle between the connections is 180º.
O=C=O
Methane gas (CH4) is one of the gases that contribute to global warming. It is the simplest hydrocarbon, being produced, for example, in the decomposition of organic matter and in the digestion process of some herbivores.
The geometry of the CH molecule4 it is tetrahedral. Methane gas is a compound formed by 5 atoms and carbon, which is the central atom, contains 4 ligands. The angle that allows for the greatest distance between its axes is 109º28’.
Allotropy is the ability of a chemical element to form different simple substances. Oxygen, for example, has two allotropes: oxygen gas (O2), indispensable for aerobic beings, and ozone (O3), which protects the planet against ultraviolet rays from the Sun.
Molecules formed by two atoms (diatomic) have linear geometry. Triatomic molecules can be linear or angular.
In the case of ozone (O3), the geometry is angular because the central atom contains an available nonbonding electron pair.
(Uespi) Associate the left column with the right column, relating the chemical species with its respective molecular geometry, and mark the correct sequence, from top to bottom:
ONLY3 it presents planar trigonal geometry, because the central atom of sulfur (S) contains 3 ligands.
PCl5 presents trigonal bipyramid geometry, as the central atom of phosphorus (P) contains 5 ligands.
H2O it presents angular geometry, as the central oxygen atom (O) contains 2 ligands and available paired electron pairs.
NH4+ it has a tetrahedral geometry, as the central nitrogen atom (N) contains 4 ligands.
CO2 presents linear geometry, because the central carbon atom (C) contains 2 ligands and there are no available pairs of electrons.
(UFRGS) Sulfur dioxide, in contact with air, forms sulfur trioxide which, in turn, in contact with water, forms sulfuric acid.
In the left column, below, 5 substances involved in this process are listed. In the right column, characteristics of the molecules of that substance.
H2ONLY4: tetrahedral geometry and polar molecule
ONLY2: angular geometry and polar molecule, as well as the molecule of H2O
O2: linear geometry and nonpolar molecule
ONLY3: trigonal geometry and nonpolar molecule
Molecules formed by a type of chemical element, such as oxygen (O2) are nonpolar because they do not show difference in electronegativity between their components.
When there is a difference in electronegativity between atoms, the geometry determines whether the molecule is polar or nonpolar.
For example, sulfur trioxide (SO3) is nonpolar due to trigonal geometry that makes the resulting dipole moment of the molecule equal to zero. On the other hand, sulfur dioxide (SO2) with its angular geometry makes the molecule polar because the dipole moment vector is non-zero.
(Ufes) The OF molecule2 is polar, and the BeF molecule2 it is non-polar. This is due to (to):
a) WRONG. When there is a difference in electronegativity in the molecules, what determines the polarity is the geometry.
b) CORRECT. As oxygen difluoride (OF2) has unpaired pairs of electrons, an angular structure is formed and the resulting dipole moment is different from zero, characterizing it as a polar molecule.
In beryllium difluoride (BeF2), the central atom does not have unpaired electrons and, therefore, its geometry is linear, making the dipole moment equal to zero and the molecule nonpolar.
c) WRONG. The size of the atoms influences the spatial structure of the molecule.
d) WRONG. Reactivity is related to the ability to form bonds.
e) WRONG. In fact, it is the polarity of the molecule that influences many properties, including the boiling point (passage to the gaseous state).
BATISTA, Carolina. Exercises on molecular geometry (with commented template).All Matter, [n.d.]. Available in: https://www.todamateria.com.br/geometria-molecular-exercicios/. Access at:
