The screening constant (σ) is the quantity subtracted from the actual nuclear charge Z to give the effective nuclear charge, and it represents the degree to which other electrons shield a given electron from the nucleus. A larger screening constant means stronger shielding and a weaker net attraction. Its value can be estimated using Slater's rules.

屏蔽常数(σ)是从实际核电荷 Z 中减去以得到有效核电荷的量,表示其他电子对某电子相对于原子核的屏蔽程度。屏蔽常数越大,屏蔽越强,净吸引越弱。其数值可用斯莱特规则估算。