You memorize the different configurations/bond angles, and what geometry the produce. Or, simply look it up in a table.
I believe it would be a T-shaped molecule because it has 3 bonding pairs and 2 lone pairs.
it shows tetrahedral geometry for the electron pairs geometry and trigonal pyramid the molecular geometry.
The Valence shell electron pair repulsion, or VSEPR is a simple technique for predicting the shape or geometry of atomic centers. The VSEPR formula is used in small molecules and molecular ions.
the VSEPR theory
VSEPR stands for Valence Shell Electron Pair Repulsion, and it describes how valence (bonding) electrons are arranged around an atom, and how they are used in creating a bond. This then can be used to help predict the GEOMETRIC SHAPE of the molecule being formed.
VSEPR predict the geometry of a chemical molecule.
How atoms are arranged in a molecule.
A. The geometry it will have
The bond anhles are 109.5 degrees so it is tetrahedral.
trigonal bipyramidal, there are 5 e- by VSEPR method
The molecular geometry of this molecule is bent. Click on the related link for a Wikipedia article that contains a VSEPR table.
According the VSEPR theory of molecular geometry, the geometry of SCl2 would be the same as H2O which is a bent angle
A pyramidal molecule
VSEPR theory
The molecular geometry of a molecule can be determined using the VSEPR theory. VSEPR (Valence Shell Electron Pair Repulsion) Theory: The basic premise of this simple theory is that electron pairs (bonding and nonbonding) repel one another; so the electron pairs will adopt a geometry about an atom that minimizes these repulsions. Use the method below to determine the molecular geometry about an atom. Write the Lewis dot structure for the molecule. Count the number of things (atoms, groups of atoms, and lone pairs of electrons) that are directly attached to the central atom (the atom of interest) to determine the overall (electronic) geometry of the molecule. Now ignore the lone pairs of electrons to get the molecular geometry of the molecule. The molecular geometry describes the arrangement of the atoms only and not the lone pairs of electrons. If there are no lone pairs in the molecule, then the overall geometry and the molecular geometry are the same. If the overall geometry is tetrahedral, then there are three possibilities for the molecular geometry; if it is trigonal planar, there are two possibilities; and if it is linear, the molecular geometry must also be linear. The diagram below illustrates the relationship between overall (electronic) and molecular geometries. To view the geometry in greater detail, simply click on that geometry in the graphic below. Although there are many, many different geometries that molecules adopt, we are only concerned with the five shown below.
BCl3 is non-polar. The B-Cl bonds are polar but the molecule is not. You should review shapes of molecules. Valence Shell Electron Pair Repulsion, VSEPR. Applying VSEPR on BCl3, we can find out that the shape of the molecule is trigonal planar. Due to its geometry, the bonds cancel out.
How atoms are arranged in a molecule.