Answer:
Simple molecules, also known as covalent molecules, are made up of two or more non-metal atoms that share electrons to form a covalent bond. The shape of a simple molecule is determined by the arrangement of its atoms in space, which is influenced by the number of electron pairs surrounding the central atom and the repulsion between them.
In general, there are two types of electron pairs: bonding pairs and non-bonding pairs (also known as lone pairs). Bonding pairs are shared between two atoms and create a strong bond that holds the molecule together. Non-bonding pairs are not shared and exert a repulsive force on the other electron pairs in the molecule.
The repulsion between electron pairs determines the shape of the molecule. For example, if a molecule has two electron pairs (a bonding pair and a non-bonding pair), they will arrange themselves as far apart as possible, which results in a linear shape. If a molecule has three electron pairs (two bonding pairs and one non-bonding pair), they will arrange themselves in a trigonal planar shape. If a molecule has four electron pairs (three bonding pairs and one non-bonding pair), they will arrange themselves in a tetrahedral shape.
Overall, the shape of a simple molecule is determined by the number of electron pairs and the repulsion between them.