effective nuclear charge

简明释义

有效核电荷

英英释义

例句

1.Understanding the effective nuclear charge helps explain trends in ionization energy.

理解有效核电荷有助于解释电离能的趋势。

2.The effective nuclear charge felt by an electron is less than the actual nuclear charge due to shielding effects.

由于屏蔽效应，电子感受到的有效核电荷低于实际核电荷。

3.As you move across a period in the periodic table, the effective nuclear charge increases.

当你在周期表中向右移动时，有效核电荷增加。

4.The concept of effective nuclear charge is crucial for understanding atomic structure.

对理解原子结构来说，有效核电荷的概念至关重要。

5.The effective nuclear charge can be calculated using Slater's rules.

可以使用斯莱特规则计算有效核电荷。

作文

The concept of effective nuclear charge is crucial in understanding the behavior of electrons in atoms. It refers to the net positive charge experienced by an electron in a multi-electron atom. This value is not simply equal to the actual nuclear charge, which is the total number of protons in the nucleus, but rather takes into account the shielding effect caused by other electrons. The effective nuclear charge helps explain various atomic properties, such as ionization energy, atomic radius, and electronegativity.In a hydrogen atom, there is only one electron and one proton, so the effective nuclear charge is equal to the actual nuclear charge of +1. However, in larger atoms, electrons in inner shells can shield outer electrons from the full attractive force of the nucleus. For example, in a sodium atom (Na), which has 11 protons and 11 electrons, the inner electrons (1s, 2s, and 2p) partially shield the outer 3s electron from the nucleus. As a result, the effective nuclear charge felt by the outer electron is less than +11. The concept of effective nuclear charge can be quantified using Slater's rules, which provide a systematic way to calculate the shielding effect based on the distribution of electrons in different orbitals. According to these rules, electrons in the same group contribute less to the shielding of each other compared to electrons in inner shells. This means that the greater the number of inner electrons, the higher the shielding effect, leading to a lower effective nuclear charge for the outermost electrons.Understanding the effective nuclear charge is essential for predicting trends in the periodic table. For instance, as you move across a period from left to right, the number of protons increases while the number of inner shell electrons remains constant. This leads to an increase in the effective nuclear charge, resulting in stronger attraction between the nucleus and the valence electrons. Consequently, atomic radii decrease across a period, and ionization energies increase.Conversely, when moving down a group in the periodic table, the number of electron shells increases, leading to increased shielding. Although the nuclear charge increases due to more protons, the effective nuclear charge experienced by the outermost electrons does not increase significantly because of the added inner shell electrons. This results in larger atomic radii and lower ionization energies as you move down a group.In summary, the concept of effective nuclear charge is fundamental to understanding atomic structure and behavior. It explains how electrons are influenced by the positive charge of the nucleus and how their interactions lead to various chemical properties. By grasping this concept, students can better appreciate the underlying principles that govern the periodic trends observed in the elements, enhancing their overall understanding of chemistry and atomic theory.

有效核电荷的概念对于理解原子中电子的行为至关重要。它指的是多电子原子中电子所经历的净正电荷。这个值不仅仅等于实际的核电荷，即核中质子的总数，而是考虑到其他电子所造成的屏蔽效应。有效核电荷有助于解释各种原子特性，如电离能、原子半径和电负性。在氢原子中，只有一个电子和一个质子，因此有效核电荷等于+1的实际核电荷。然而，在较大的原子中，内层电子会对外层电子施加部分屏蔽，使其无法感受到核的全部吸引力。例如，在钠原子（Na）中，它有11个质子和11个电子，内层电子（1s、2s和2p）部分屏蔽了外层的3s电子。因此，外层电子所感受到的有效核电荷低于+11。有效核电荷的概念可以使用斯莱特规则进行量化，这提供了一种系统的方法来计算基于不同轨道中电子分布的屏蔽效应。根据这些规则，同一组中的电子对彼此的屏蔽贡献较少，而内层电子则贡献更多。这意味着内层电子的数量越多，屏蔽效应越强，从而导致外层电子的有效核电荷降低。理解有效核电荷对于预测周期表中的趋势至关重要。例如，当你从左到右移动一个周期时，质子的数量增加，而内层电子的数量保持不变。这导致有效核电荷的增加，导致核与价电子之间的吸引力增强。因此，原子半径在一个周期内减小，而电离能增加。相反，当在周期表中向下移动一个族时，电子壳层的数量增加，导致屏蔽效应增强。尽管由于质子增加，核电荷也在增加，但外层电子所经历的有效核电荷并没有显著增加，因为增加了内层电子。这导致当你向下移动一个族时，原子半径增大，电离能降低。总之，有效核电荷的概念是理解原子结构和行为的基础。它解释了电子如何受到核正电荷的影响，以及它们之间的相互作用如何导致各种化学特性。通过掌握这一概念，学生能够更好地欣赏到支配元素观察到的周期趋势的基本原理，从而增强他们对化学和原子理论的整体理解。