SHAPES OF MOLECULAR COMPOUNDS

The shapes of molecular compounds are determined by the arrangement of their atoms and the number of lone pairs on the central atom. The most common shapes are linear, planar, tetrahedral, trigonal bipyramidal, and octahedral. Here are the shapes for some commonly studied compounds:

• BeCl2 – Linear
• BF3 – Planar (Trigonal Planar)
• CH4 – Tetrahedral
• NH3 – Planar (Trigonal Pyramidal)
• CO2 – Linear

 

1) In BeCl2, the central atom (Be) has no lone pairs, and the two bonded atoms (Cl) are arranged linearly. Therefore, the shape is linear.

 

2) In BF3, the central atom (B) has no lone pairs, and the three bonded atoms (F) are arranged in a plane around the central atom. Therefore, the shape is planar or trigonal planar.

 

3) In CH4, the central atom (C) has four bonded atoms (H) arranged tetrahedrally around it with bond angles of 109.5 degrees. Therefore, the shape is tetrahedral.

 

4) In NH3, the central atom (N) has three bonded atoms (H) and one lone pair arranged trigonally around it, with bond angles of approximately 107 degrees. Therefore, the shape is planar or trigonal pyramidal.

 

5) In CO2, the central atom (C) has two bonded atoms (O) arranged linearly on opposite sides. Therefore, the shape is linear.

 

Here is a list of some common shapes of other molecular compounds, along with examples:

Linear: Molecules with two atoms or three atoms arranged in a straight line. Examples include CO2, HCN, and BeCl2.

Trigonal planar: Molecules with three atoms arranged in a flat triangle. Examples include BF3, CO32-, and SO32-.

Tetrahedral: Molecules with four atoms arranged in a three-dimensional shape resembling a four-sided pyramid. Examples include CH4, NH4+, and CF4.

Trigonal bipyramidal: Molecules with five atoms arranged in a three-dimensional shape resembling two pyramids joined at their bases. Examples include PCl5 and PF5.

Octahedral: Molecules with six atoms arranged in a three-dimensional shape resembling two square-based pyramids joined at their bases. Examples include SF6 and XeF6.

Bent or V-shaped: Molecules with three atoms in which the central atom has a lone pair of electrons causing the molecule to be angular. Examples include H2O and SO2.

T-shaped: Molecules with three atoms in which the central atom has two lone pairs of electrons causing the molecule to have a T-shape. Examples include ClF3.

Square planar: Molecules with four atoms in which the central atom has two lone pairs of electrons causing the molecule to have a square shape. Examples include PtCl4.

Note that this is not an exhaustive list, and there are many other possible molecular shapes, particularly for larger and more complex molecules.