Effective Nuclear Charge
Effective Nuclear Charge - Related Videos
03:08
Atomic Radii and Effective Nuclear Charge
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2020
The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number and distribution of electrons in their valence shells. Going across a period from left to right, a proton is added to the nucleus and an electron to the valence shell with each successive element. Going down the elements in a group, the number of electrons in the valence shell remains constant, but the principal quantum number increases by...
04:36
Production of Synthetic Nuclear Melt Glass
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Cited by 1 •
2016
A protocol for the production of synthetic nuclear melt glass, similar to trinitite, is presented.
03:20
Nuclear Transmutation
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2020
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed protons being...
02:42
Formal Charges
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2020
In some cases, there are seemingly more than one valid Lewis structures for molecules and polyatomic ions. The concept of formal charges can be used to help predict the most appropriate Lewis structure when more than one reasonable structure exists. Calculating Formal Charge The formal charge of an atom in a molecule is the hypothetical charge the atom would have if the electrons in the bonds are evenly distributed between the atoms. Alternatively, formal charge results when from the number...
03:27
Ions and Ionic Charges
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2020
In ordinary chemical reactions, the nucleus — which contains the protons and neutrons of each atom and thus identifies the element — remains unchanged. Electrons, however, can be added to atoms by transfer from other atoms, lost by transfer to other atoms, or shared with other atoms. The transfer and sharing of electrons among atoms govern the chemistry of the elements. During the formation of some compounds, atoms gain or lose electrons to form electrically charged particles called ions. When...
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The nucleus gains protons as atomic number increases across a period, strengthening its positive attraction. At the same time, added electrons enter the same principal shell, so shielding changes relatively little compared with the rise in nuclear charge. The resulting increase in effective nuclear charge helps explain why electrons experience stronger nuclear attraction across a period.
Moving down a group introduces additional occupied electron shells between the nucleus and outer electrons. These inner shells increase shielding, reducing how strongly the outer electrons experience the nucleus even though proton number also rises. This balance is important for understanding why periodic behavior down a group differs from the left-to-right pattern.
Inner-shell electrons provide the major shielding effect because they lie between the nucleus and the electron being considered. Electrons in the same shell can also reduce the nuclear attraction, but their shielding contribution is smaller. Distinguishing these roles allows chemists to compare how strongly different electrons are attracted within an atom.
First compare the number of protons, then identify whether the electrons being considered occupy the same shell or different shells. A larger proton number with little change in shielding suggests a greater effective nuclear charge, whereas additional inner shells indicate stronger shielding. This qualitative procedure supports comparisons without treating nuclear charge and shielding as identical factors.
When effective nuclear charge becomes larger across a period, the nucleus attracts electrons more strongly while shielding changes relatively little. The electron cloud is therefore associated with a stronger inward pull, helping explain periodic changes in atomic radius. Down a group, added shells increase shielding and contribute to the contrasting trend in atomic size.
Effective nuclear charge provides a common framework for relating nuclear attraction to several periodic properties. Changes in that attraction help account for trends in the energy required to remove an electron, the tendency associated with gaining one, and differences in chemical reactivity. It therefore connects electron arrangement with observable chemical behavior in periodic comparisons.