What is bond angle?

Answer 1

In any given molecule, the atoms will have a specific position with relation to the other atoms in the molecule, and if we draw imaginary lines from the nucleus of one atom to the nucleus of another atom, the lines are going to form angles, which are called bonding angles because they are the result of chemical bonds. For example, the water molecule forms approximately a 120o angle if you trace a line from one hydrogen, to the central oxygen, and then to the other hydrogen.

Answer 2

A covalently bonded molecule has a specific equilibrium configuration in three dimensional space with respect to the distance and direction in space between any two of its atoms. When one atom in the molecule is covalently bonded to at least two distinct other atoms, the angle between hypothetical lines connecting the center the of the atom bonded to the centers of at least two other distinct atoms is called the "bond angle" between those three atoms. (The "distinct" atoms in this definition may each be atoms of the same isotope of the same element, but they are distinct because there are at least two such atoms.) For example, in methane, which has the molecular formula CH4, the four hydrogen atoms are known to be positioned at the corners of a tetrahedron with the carbon atom at the center of the tetrahedron, and every H-C-H bond angle is about 109 degrees.