Question

In periods 4 and beyond, what are the roles of core and valence electrons?

a) Core electrons are involved in chemical bonding.
b) Core electrons are responsible for reactivity.
c) Valence electrons determine chemical properties.
d) Valence electrons are non-reactive.

Answer 1

Core electrons do not usually participate in chemical bonding and contribute to the atom's shielding effect, whereas valence electrons are involved in chemical bonding and determine the atom's reactivity and chemical properties, especially in atoms in period 4 and beyond.

Step-by-step explanation:

The core and valence electrons play different roles in atoms, especially from period 4 and beyond in the periodic table. Valence electrons are the electrons located in the outermost shell of an atom and are crucial in determining the atom's chemical properties and reactivity. These electrons can participate in the formation of chemical bonds. When the valence shell is not full, the atom seeks to fill it, making it more reactive. On the contrary, core electrons are those found in the shells closer to the nucleus and do not generally participate in chemical bonding. Instead, they provide a shielding effect that influences the effective nuclear charge felt by the valence electrons, but they do not directly affect reactivity as valence electrons do. Atoms with a full outer valence shell are more stable and less likely to engage in chemical reactions.