Neils bohr published his model of the atomic structure in 1913. he introduced the theory of electrons traveling in orbits around the atom's nucleus, with electrons orbiting only in certain orbits called shells. each shell can contain a fixed number of electrons. according to this model of the atom, the chemical properties of an element are mainly determined by a) the number of electrons in the outer shells. b) the number of electrons in the inner shells. c) the total number of electrons in all shells. d) the difference between number of electrons and protons. elim

A)  the number of electrons in the outer shells.

Explanation:

The Bohr's model of the atoms shows that electrons orbits the nucleus in energy levels that are discrete and quantised. Orbital electrons are pulled by the nucleus. The nuclear pull is strongest on the shells closer to the nucleus and weakest as we reach the outermost sphere.

From this model, we see that chemical properties are governed by how much electrons an atom is ready to lose from its outermost shell in which the energy is the lowest. It is the electrons in the outermost shell or valence shell that determines how atoms would behave chemically.