Answer:
Si ⇔ Neon
Fr ⇔ Radon
Hg ⇔Xenon
V ⇔Argon
Step-by-step explanation:
Silicon (Si) is, part of the carbon-group, and has atomic number 14. This means it has 14 protons and 14 elecrons ( same amount), as well as 14 protons ( 28-14).
⇒There are 14 electrons spread over 3 shells.
If we look closer to the electron configuration of a silicon atom:
₁₄Si 1s² 2s² 2p⁶ 3s² 3p² ⇔ this is [Ne] 3s² 3p²
⇒ Neon (Ne) is noble gas ( group 18) with atomic number 10.
⇒The following orbital is 3s, which is complete with 2 electrons.
⇒The next orbital is 3p, and Silicon is the second element in that section, so two electrons are used.
Francium (Fr) is part of the alkali / lithium group and has atomic number 87. This means it has 87 protons and 87 electrons ( same amount), and 136 neutrons (223 - 87).
⇒There are 87 electrons spread over 7 shells.
If we look closer to the electron configuration of a francium atom:
₈₇Fr 1s²2s²2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 7s¹ ⇔ this is [Rn] 7s¹
⇒ radon (Rn) is noble gas( group 18) with atomic number 86
⇒we will see that the 4 s orbital fills with electrons before any of those in the 3 d subshell as the 4 s orbital is lower in energy than the 3 d s, and it is favorable for electrons to fill low-energy orbitals first (closer to the nucleus)
⇒Francium will fill orbitals all the way up to the 7 s subshell, where it will have a half-filled orbital: 7 s 1
Mercury (Hg) is part of the zinc group, and has atomic number 80. This means it has 80 protons and 80 electrons ( same amount), and 121 neutrons ( 201 - 80).
⇒There are 80 electrons spread over 6 shells
If we look closer to the electron configuration of a Mercury atom:
₈₀Hg 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² ⇔ this is[Xe] 4f¹⁴ 5d¹⁰ 6s²
⇒xenon (Xe) is noble gas ( group 18) with atomic number 54.
⇒After the 6s orbital is filled, 4f fills next (can hold 14 electrons) because it lower in energy than 5d.
⇒Then, the 10 remaining electrons will go in the 5d orbital. The f orbitals will always be one principle quantum number(n) behind the d orbitals.
Vanadium (V) is part of the vanadium group, and has atomic number 23. This means it has 23 protons and 23 electrons (same amount), and 28 neutrons (51 - 23).
⇒There are 23 electrons spread over 4 shells
If we look closer to the electron configuration of a vanadium atom:
₂₃V 1s² 2s² 2p⁶ 3s² 3p⁶ 3d³ 4s² ⇔ this is [Ar] 3d³ 4s²
⇒argon (Ar) is a noble gas (group 18) with atomic number 54.
⇒ When the atom of V releases 5 electrons from 3d and 4s orbital, V ion (V5+) will attain the octet structure, 1s2 2s2 2p6 3s2 3p6 which is same as Argon