Question

Name the element described in each of the following: (a) Smallest atomic radius in Group \(6 \mathrm{~A}(16)\) (b) Largest atomic radius in Period 6 (c) Smallest metal in Period 3 (d) Highest IE \(_{1}\) in Group \(4 \mathrm{~A}(14)\) (e) Lowest IE \(_{1}\) in Period 5 (f) Most metallic in Group \(5 \mathrm{~A}(15)\) (g) Group \(3 \mathrm{~A}(13)\) element that forms the most basic oxide (h) Period 4 element with highest energy level filled (i) Condensed ground-state electron configuration of [Ne] \(3 s^{2} 3 p^{2}\) (j) Condensed ground-state electron configuration of \([\mathrm{Kr}] 5 s^{2} 4 d^{6}\) (k) Forms \(2+\) ion with electron configuration [Ar] \(3 d^{3}\) (1) Period 5 element that forms \(3+\) ion with pseudo-noble gas configuration (m) Period 4 transition element that forms \(3+\) diamagnetic ion (n) Period 4 transition element that forms \(2+\) ion with a half-filled \(d\) sublevel (o) Heaviest lanthanide (p) Period 3 element whose \(2-\) ion is isoelectronic with Ar (q) Alkaline earth metal whose cation is isoelectronic with \(\mathrm{Kr}\) (r) Group \(5 \mathrm{~A}(15)\) metalloid with the most acidic oxide

Short answer

a) Oxygen (O) b) Cesium (Cs) c) Aluminium (Al) d) Carbon (C) e) Rubidium (Rb) f) Bismuth (Bi) g) Thallium (Tl) h) Krypton (Kr) i) Silicon (Si) j) Ruthenium (Ru) k) Vanadium (V) l) Indium (In) m) Scandium (Sc) n) Manganese (Mn) o) Lutetium (Lu) p) Sulfur (S) q) Calcium (Ca) r) Arsenic (As)

Step-by-step solution

Smallest atomic radius in Group 6A(16)

To find the element with the smallest atomic radius in Group 16, look at the position of Group 16 elements in the periodic table. The atomic radius decreases as you move up a group. The elements in Group 16 are O, S, Se, Te, and Po. The smallest atomic radius will be at the top. Thus, the answer is Oxygen (O).

Largest atomic radius in Period 6

In a given period, atomic radius increases as you move from right to left. The elements in Period 6 are Cs, Ba, La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Po, At, Rn. The first element in the period has the largest atomic radius, which is Cesium (Cs).

Smallest metal in Period 3

In Period 3, the elements are Na, Mg, Al, Si, P, S, Cl, Ar. Out of these, the metals are Na, Mg, and Al. The smallest metal in terms of atomic radius is Aluminium (Al).

Highest IE₁ in Group 4A(14)

Ionization energy generally increases as you go up a group. The elements in Group 14 are C, Si, Ge, Sn, and Pb. The highest IE₁ corresponds to the element at the top of the group, which is Carbon (C).

Lowest IE₁ in Period 5

In Period 5, look for the element with the lowest ionization energy, which typically corresponds to the leftmost element. The Period 5 elements are Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Xe. Rubidium (Rb) has the lowest IE₁.

Most metallic in Group 5A(15)

The metallic character increases as you move down a group. Group 15 elements are N, P, As, Sb, Bi. Thus, Bismuth (Bi) is the most metallic.

Most basic oxide in Group 3A(13)

Basicity of oxides increases down the group. The elements in Group 13 are B, Al, Ga, In, and Tl. The most basic oxide is formed by Thallium (Tl).

Highest energy level filled in Period 4

The elements in Period 4 have their valence electrons filling up to the 4th energy level. The filling sequence ends with the 4p element. Thus Krypton (Kr) has the highest energy level filled.

Electron configuration [Ne] 3s²3p²

The electron configuration [Ne] 3s² 3p² corresponds to the element Silicon (Si).

Electron configuration [Kr] 5s²4d⁶

The electron configuration [Kr] 5s² 4d⁶ corresponds to the element Ruthenium (Ru).

Forms 2+ ion with [Ar] 3d³ configuration

The ion with the configuration [Ar] 3d³ comes from Vanadium (V) with a 2+ charge.

Forms 3+ ion with pseudo-noble gas configuration in Period 5

For Period 5, we look for the element that forms a 3+ ion with a pseudo-noble gas configuration. Indium (In) forms a 3+ ion with an electron configuration [Kr] 4d¹⁰, which is pseudo-noble gas.

Forms 3+ diamagnetic ion in Period 4 transition elements

A 3+ ion that is diamagnetic has all paired electrons. Scandium (Sc) forms Sc³⁺ which is diamagnetic.

Forms 2+ ion with a half-filled d sublevel in Period 4

For a 2+ ion with a half-filled d sublevel, we look for an element with a d⁵ configuration. Manganese (Mn) forms Mn²⁺ with a 3d⁵ configuration.

Heaviest lanthanide

The heaviest lanthanide in terms of atomic mass is Lutetium (Lu).

Period 3 element whose 2- ion is isoelectronic with Ar

The element in Period 3 whose 2- ion is isoelectronic with Argon (Ar) is Sulfur (S).

Alkaline earth metal cation isoelectronic with Kr

We look for an alkaline earth metal in Group 2 whose cation is isoelectronic with Krypton (Kr). Calcium (Ca) forms the Ca²⁺ ion which is isoelectronic with Kr.

Group 5A(15) metalloid with the most acidic oxide

The metalloid in Group 5A (15) is Arsenic (As), and it has the most acidic oxide.

Key concepts

Atomic Radius

The atomic radius of an element is the distance from the nucleus to the outermost electron shell. Understanding trends in atomic radius is crucial for various applications, such as predicting reactivity and bonding behavior.

Atomic radius generally decreases across a period from left to right. This happens because as protons are added to the nucleus, the positive charge increases, pulling electrons closer to the nucleus.

Conversely, atomic radius increases as you move down a group. This is due to the addition of electron shells, which increases the distance between the nucleus and the outer shell electrons, outweighing the increase in nuclear charge.

For instance, in Group 16 (O, S, Se, Te, Po), Oxygen (O) has the smallest atomic radius because it is at the top of the group. In Period 6, Cesium (Cs) has the largest atomic radius because it's at the bottom left of the periodic table.

Ionization Energy

Ionization energy (IE) is the energy required to remove an electron from a gaseous atom or ion. The first ionization energy refers specifically to removing the first electron.

Ionization energy increases across a period from left to right due to an increase in nuclear charge without a proportional increase in shielding. As a result, electrons are held more tightly and require more energy to remove.

On the other hand, ionization energy decreases as you move down a group. This is because the distance between the nucleus and the outermost electron increases, making it easier to remove the electron.

For example, within Group 14, Carbon (C) has the highest first ionization energy as it is at the top of the group. In Period 5, Rubidium (Rb) has the lowest first ionization energy because it is at the far left.

Metallic Character

Metallic character refers to how easily an element can lose an electron, a key trait for metals. It is generally indicated by characteristics such as high electrical conductivity, luster, and malleability.

Metallic character decreases across a period from left to right. This is due to the increased nuclear charge, which holds electrons more tightly, making it more difficult for atoms to lose electrons.

Conversely, metallic character increases as you move down a group. The additional electron shells make it easier for the outermost electrons to be lost.

For instance, in Group 15, Bismuth (Bi), located at the bottom of the group, is the most metallic. Similarly, in Period 3, Aluminum (Al) is identified as a small metal based on its atomic radius and metallic nature.

Electron Configuration

Electron configuration is the arrangement of electrons in the orbitals of an atom or ion. It follows the principles of quantum mechanics and helps in predicting the chemical behavior of elements.

Each electron configuration describes the number of electrons in each shell and subshell (s, p, d, f). Electrons fill orbitals starting with the lowest energy levels—beginning from 1s, then 2s, 2p, and so on.

The electron configurations build from the innermost shells outward and can be written in a condensed form, using the noble gas from the previous period as a reference point. For example, Silicon (Si) has the configuration [Ne] 3s²3p², and Ruthenium (Ru) has the configuration [Kr] 5s²4d⁶.

Knowing an element's electron configuration is essential for understanding its reactivity and placement in the periodic table.