In an atom with a single electron, the electron experiences the full nuclear charge, which is the total charge of the atom's protons. But most atoms have more than one electron. In these atoms, the electrons only experience some of the atom's nuclear charge. The amount of nuclear charg an electron experiences depends on the number and arrangement of other electrons in the atom. The electrons in an atom are arranged in specific energy levels. Valence electrons are those in the outermost energy level, while core electrons are between the valence electrons and the nucleus. All electrons are simultaneously attracted to the nucleus and repelled by other electrons. When core electrons repel valence electrons, they shield the valence electrons from the f nucleus. As a result, the valence electrons AY experience a weakened positive charge. The (3+) : \\ . attraction net positive charge an electron experiences is ] repulsion called the effective nuclear charge (Z.;;). RZ Bohr model of lithium Complete the sentences. A lithium atom has 4 nuclear charge of 3+ and two electrons. These electrons shield lithium's one electron from the nucleus. So a valence electron in a lithium atom experiences an effective nuclear charge 3+