Answer: The shielding effect, also known as the screening effect describes how electrons in an atom can shield or block the positive charge of the nucleus from other electrons. This effect is particularly noticeable in atoms with many electrons.
Here’s how it works:
- Electrons are arranged in different layers or shells around an atom’s nucleus.
- The innermost electrons are closer to the nucleus and experience a strong attraction to the positive charge of the protons in the nucleus.
- However, as more electron shells are added, the outer electrons are further away from the nucleus. These outer electrons are partially shielded from the positive charge of the nucleus by the inner electrons.
- This shielding reduces the effective nuclear charge that the outer electrons experience.
- As a result, these outer electrons are less tightly held by the nucleus and can be more easily influenced by external forces.
This concept is crucial in understanding atomic properties like ionization energy and atomic size.