Bromine (Br) has 35 electrons. The electronic configuration of Bromine can be written as 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁵.
The valence electrons of an atom are the electrons in its outermost energy level, also known as the valence shell. For Bromine, the valence shell contains 7 electrons (4s²4p⁵), so Bromine has 7 valence electrons.
The valence electrons are the electrons involved in chemical bonding, so the number of valence electrons can help determine the chemical behavior of an element. In the case of Bromine, having 7 valence electrons makes it highly reactive, and it tends to form a single covalent bond by sharing one electron with another atom to achieve a stable octet configuration.