Question

The Valence Electrons of an Atom of Which Element would feel a Greater Effective Nuclear Charge than the Valence?

The Valence Electrons of an Atom of which element would feel a greater effective Nuclear Charge than the valence electrons of a Boron (B) atom?

Aluminum (Al)
Beryllium (Be)
Hydrogen (H)
Carbon (C)

Answer 1

Carbon's valence electrons feel a greater effective nuclear charge than those of a Boron atom because Carbon has one more proton without significantly increasing the shielding effect, leading to a stronger pull on the valence electrons.

Step-by-step explanation:

The question asks which element's valence electrons feel a greater effective nuclear charge than those of a Boron (B) atom. To answer this, one must understand how shielding and effective nuclear charge work. As we go from left to right across a period in the periodic table, while the number of core electrons remains the same, the nuclear charge increases. This means the valence electrons feel a stronger pull from the nucleus since they are not effectively shielded by the same number of core electrons. Comparing Boron with Aluminum (Al), Beryllium (Be), Hydrogen (H), and Carbon (C), we find that Carbon, having one more proton than Boron, does not increase the shielding effect significantly, which leads to its valence electrons feeling a greater effective nuclear charge than Boron's. Therefore, Carbon (C) is the correct response.

Answer 2

The effective nuclear charge is an innate property of a specific element. It is the pull of force that an electron feels from the nucleus. It is related to the valence electron by the equation: Z* = Z-S, where Z* is the effective nuclear charge, Z is the atomic number and S is the shielding constant.

For the following elements in the choices, these are their values of Z*:

Aluminum - +12.591
Beryllium - +1.912
Hydrogen - +1
Carbon - +4

The effective nuclear charge of Boron is +3. Thus, the answers are Aluminum and Carbon.