Passage
Dmitri Mendeleev is credited with grouping the elements by atomic mass and observing that similar properties emerge periodically. Henry Moseley then determined that a fundamental property, which Ernest Rutherford later called the atomic number, is more important than atomic mass for ordering the elements.As the periodic table took shape, scientists noted certain properties and trends. For example, Rayleigh and Ramsay observed that some elements are unreactive and gave them the name noble gases. But it was not until Niels Bohr described his model of the atom that scientists understood why noble gases are stable.Another important trend was discovered by Linus Pauling. He was the first to identify electronegativity as a way to describe bonds that are neither completely ionic nor completely covalent. Pauling assigned fluorine the highest electronegativity value of 4.0 because of its strong tendency to attract electrons when bonded to other atoms. All other atoms were assigned values relative to fluorine. This became known as the Pauling electronegativity scale.Scientists identified other trends based on x-ray crystallography and reactivity studies. Figure 1 shows the first ionization energy of the elements, and Figure 2 shows electron affinity.
Figure 1 First ionization energy of elements
Figure 2 Electron affinity of several elements (larger negative values indicate greater electron affinity)
-Why are noble gases the least reactive group on the periodic table?

Question

Passage
Dmitri Mendeleev is credited with grouping the elements by atomic mass and observing that similar properties emerge periodically. Henry Moseley then determined that a fundamental property, which Ernest Rutherford later called the atomic number, is more important than atomic mass for ordering the elements.As the periodic table took shape, scientists noted certain properties and trends. For example, Rayleigh and Ramsay observed that some elements are unreactive and gave them the name noble gases. But it was not until Niels Bohr described his model of the atom that scientists understood why noble gases are stable.Another important trend was discovered by Linus Pauling. He was the first to identify electronegativity as a way to describe bonds that are neither completely ionic nor completely covalent. Pauling assigned fluorine the highest electronegativity value of 4.0 because of its strong tendency to attract electrons when bonded to other atoms. All other atoms were assigned values relative to fluorine. This became known as the Pauling electronegativity scale.Scientists identified other trends based on x-ray crystallography and reactivity studies. Figure 1 shows the first ionization energy of the elements, and Figure 2 shows electron affinity.

Figure 1 First ionization energy of elements

Figure 2 Electron affinity of several elements (larger negative values indicate greater electron affinity)
-Why are noble gases the least reactive group on the periodic table?

Quizplus · Accepted Answer

11ecba2d_11c0_b83c_a3bf_8db6b062a558_MD0008_00 Noble gases have full s and p orbitals in their valence shells except for helium, which has only a full s orbital in its valence shell. For each energy level n, the s orbital can house two electrons and the p orbitals six electrons, for a total of eight electrons. Because the valence orbitals are filled, it is not possible to accept another electron at that energy level, and it is energetically unfavorable to accept more electrons at higher levels. Given that reactivity is driven by the tendency of atoms to gain, lose, or share electrons to achieve a more stable electronic configuration, noble gases tend to be unreactive (except in extreme cases) as they already possess an energetically favorable configuration. (Choice A) Although it is true that noble gases are diamagnetic (no unpaired electrons), having paired electrons does not mean that an atom is unreactive. For example, magnesium has no unpaired electrons but it reacts readily with several Group 6A and Group 7A elements. (Choice C) The number of protons and neutrons does not determine an atom's reactivity. Atoms are reactive based on their electron configuration. (Choice D) Diatomic elements naturally occur in a covalently bonded pair, which allows each atom in the pair to achieve a full valence shell. For example, hydrogen is typically found as H₂ and oxygen is typically found as O₂. However, noble gases are not diatomic because they already have a full valence shell of electrons. Educational objective: Reactivity is driven by the tendency of atoms to gain, lose, or share electrons to achieve a more stable electronic configuration (ie, a full valence shell). Noble gases are generally unreactive because they already have a full valence shell of electrons.

Passage Dmitri Mendeleev Is Credited with Grouping the Elements by Atomic