Ammonia has a trigonal pyramidal shape. This shape is a result of the three covalent bonds between the nitrogen atom and the three hydrogen atoms. The nitrogen atom has three valence electrons, and each hydrogen atom has one valence electron. When these atoms bond, the nitrogen atom shares its three valence electrons with the three hydrogen atoms, and each hydrogen atom shares its one valence electron with the nitrogen atom. This results in a tetrahedral electron cloud around the nitrogen atom. However, the four pairs of electrons are not all equivalent. There are three bonding pairs of electrons and one lone pair of electrons. The three bonding pairs of electrons are arranged in a trigonal plane, and the lone pair of electrons is located at the top of the pyramid. This gives ammonia its trigonal pyramidal shape.