Sky blue ball=nitrogen atomYellow ball=hydrogen ball
Wood stick=polar covalent bond
Ammonia is on the photograph and its molecule formula is NH3.The ammonia molecule has a shape that has three hydrogen atoms connecting one nitrogen atom in a single bond and as a result, there is one lone pair in nitrogen atom to fulfill octet rule. The ammonia molecule also has a tetrahedral arrangement of election pairs but not a tetrahedral arrangement of atoms. It's structure could be tetrahedron but since hydrogen atoms in the molecule occupy only three corners of the tetrahedron, the structure of ammonia molecule is trigonal pyramid.
