Chapter 2, Problem 2.97P

Answer the following questions about the macronutrients sodium, potassium, and chlorine.
a. Is each element classified as a metal, nonmetal, or metalloid?
b. In which block does each element reside?
c. Which element has the smallest atomic radius?
d. Which element has the largest atomic radius?
e. Which element has the largest ionization energy?
f. Which element has the smallest ionization energy?
g. How many valence electrons does each element possess?

Interpretation Introduction

(a)

Interpretation:

The elements sodium, potassium, and chlorine should be classified as metal, nonmetal or metalloid.

Concept Introduction:

An atom is composed of three main sub-atomic particles; electrons, neutrons and protons. The atomic number of the elements represents the number of protons or electrons in a neutral atom. All known elements are arranged in a tabular form in increasing order of their atomic number that is called the periodic table.

The distribution of electrons in an atom can be shown with the help of electronic configuration. The electronic configuration of an element represents the number of electrons in different energy levels of an element.

Answer to Problem 2.97P

Sodium − Metal

Potassium − Metal

Chlorine − Nonmetal

Explanation of Solution

All the elements in the periodic table can be classified as metal, nonmetal and metalloid. In the periodic table, from group 1 to 12 are metals and nonmetals are placed from group 13 to 18. Metalloids are placed in between metals and nonmetals in the periodic table. Sodium and potassium are metals as they are placed in group -1 whereas chlorine is a nonmetal as it is placed in group 17 of the periodic table.

Interpretation Introduction

(b)

Interpretation:

The block in which elements sodium, potassium, and chlorine elements should be determined.

Concept Introduction:

An atom is composed of three main sub-atomic particles; electrons, neutrons and protons. The atomic number of the elements represents the number of protons or electrons in a neutral atom. All known elements are arranged in a tabular form in increasing order of their atomic number that is called the periodic table.

The distribution of electrons in an atom can be shown with the help of electronic configuration. The electronic configuration of an element represents the number of electrons in different energy levels of an element.

Answer to Problem 2.97P

Sodium − s-block element

Potassium − s-block element

Chlorine − p-block element

Explanation of Solution

All the elements in the periodic table can be classified as metal, nonmetal and metalloid. In the periodic table, from group 1 to 12 are metals and nonmetals are placed from group 13 to 18. Metalloids are placed in between metals and nonmetals in the periodic table.

The periodic table can also divide on the basis of blocks as s, p, d and f-block elements. This classification is given on the basis of valence shell configuration of elements. The valence orbital of the element will determine the block of element. Sodium and potassium are s-block element as their valence shell is ns¹ whereas Chlorine is a p-block element as the valence shell configuration of Chlorine is 3s², 3p⁵.

Sodium − ${\text{1s}}^{\text{2}}{\text{, 2s}}^{\text{2}}{\text{, 2p}}^{\text{6}}{\text{, 3s}}^{\text{1}}$

Potassium- ${\text{1s}}^{\text{2}}{\text{, 2s}}^{\text{2}}{\text{, 2p}}^{\text{6}}{\text{, 3s}}^{\text{2}}{\text{, 3p}}^{\text{6}}{\text{, 4s}}^{\text{1}}$

Chlorine - ${\text{1s}}^{\text{2}}{\text{, 2s}}^{\text{2}}{\text{, 2p}}^{\text{6}}{\text{, 3s}}^{\text{2}}{\text{, 3p}}^{\text{5}}$

Interpretation Introduction

(c)

Interpretation:

The element with smallest atomic radius out of sodium, potassium, and chlorine should be determined.

Concept Introduction:

An atom is composed of three main sub-atomic particles; electrons, neutrons and protons. The atomic number of the elements represents the number of protons or electrons in a neutral atom. All known elements are arranged in a tabular form in increasing order of their atomic number that is called the periodic table.

The distribution of electrons in an atom can be shown with the help of electronic configuration. The electronic configuration of an element represents the number of electrons in different energy levels of an element.

Answer to Problem 2.97P

Chlorine has the smallest atomic radius.

Explanation of Solution

In the periodic table, on moving down in the group the atomic radii increases as the number of valence shell increases in atom, whereas the atomic radii decreases across the period because the valence shell remains same and nuclear attraction increases. Sodium and potassium are placed in same group. Therefore, potassium should be bigger than sodium. Chlorine and sodium are placed in same period and chlorine is placed in the 17^th group (at left most side),. Therefore, the atomic radius of chlorine must be smallest.

Interpretation Introduction

(d)

Interpretation:

The element with largest atomic radius out of sodium, potassium, and chlorine should be determined.

Concept Introduction:

An atom is composed of three main sub-atomic particles; electrons, neutrons and protons. The atomic number of the elements represents the number of protons or electrons in a neutral atom. All known elements are arranged in a tabular form in increasing order of their atomic number that is called the periodic table.

The distribution of electrons in an atom can be shown with the help of electronic configuration. The electronic configuration of an element represents the number of electrons in different energy levels of an element.

Answer to Problem 2.97P

Potassium has largest atomic radius.

Explanation of Solution

In the periodic table, on moving down in the group the atomic radii increases as the number of valence shell increases in atom, whereas the atomic radii decreases across the period because the valence shell remains same and nuclear attraction increases. Sodium and potassium are placed in same group. Therefore, potassium should be bigger than sodium. Chlorine and sodium are placed in same period and chlorine is placed in the 17^th group (at left most side). Therefore, the atomic radius of chlorine must be the smallest. Overall potassium will have the largest atomic radius.

Interpretation Introduction

(e)

Interpretation:

The element with largest ionization energy out of sodium, potassium, and chlorine should be determined.

Concept Introduction:

An atom is composed of three main sub-atomic particles; electrons, neutrons and protons. The atomic number of the elements represents the number of protons or electrons in a neutral atom. All known elements are arranged in a tabular form in increasing order of their atomic number that is called the periodic table.

The distribution of electrons in an atom can be shown with the help of electronic configuration. The electronic configuration of an element represents the number of electrons in different energy levels of an element.

Answer to Problem 2.97P

Chlorine has largest ionization energy.

Explanation of Solution

In the periodic table down in the group the atomic radii increases as the number of valence shell increases in atom, whereas the atomic radii decreases across the period because the valence shell remains same and nuclear attraction increases.

Ionization energy is the energy that is required to remove an electron from the valence shell of the neutral gaseous atom. As the atomic radii increases down in the group, the nuclear attraction on the valence electrons decreases that reduces the ionization energy of element. Hence the ionization energy decreases down in the group and increases across the period.

Sodium and potassium are placed in same group. Therefore, potassium should be bigger than sodium and must have lower ionization energy. Chlorine and sodium are placed in same period and chlorine is placed in the 17^th group (at left most side),. Therefore, the atomic radius of chlorine must be smallest with largest ionization energy.

Interpretation Introduction

(f)

Interpretation:

The element with smallest ionization energy out of sodium, potassium, and chlorine should be determined.

Concept Introduction:

An atom is composed of three main sub-atomic particles; electrons, neutrons and protons. The atomic number of the elements represents the number of protons or electrons in a neutral atom. All known elements are arranged in a tabular form in increasing order of their atomic number that is called the periodic table.

The distribution of electrons in an atom can be shown with the help of electronic configuration. The electronic configuration of an element represents the number of electrons in different energy levels of an element.

Answer to Problem 2.97P

Potassium has smallest ionization energy.

Explanation of Solution

In the periodic table down in the group the atomic radii increases as the number of valence shell increases in atom, whereas the atomic radii decreases across the period because the valence shell remains same and nuclear attraction increases.

Ionization energy is the energy that is required to remove an electron from the valence shell of the neutral gaseous atom. As the atomic radii increases down in the group, the nuclear attraction on the valence electrons decreases that reduces the ionization energy of element. Hence the ionization energy decreases down in the group and increases across the period.

Sodium and potassium are placed in same group. Therefore, potassium should be bigger than sodium and must have lowest ionization energy. Chlorine and sodium are placed in same period and chlorine is placed in the 17^th group (at left most side),. Therefore, the atomic radius of chlorine must be smallest with largest ionization energy. Overall out of Na, K and Cl; K will have lowest ionization energy.

Interpretation Introduction

(g)

Interpretation:

The number of valence electrons in sodium, potassium, and chlorine should be determined.

Concept Introduction:

An atom is composed of three main sub-atomic particles; electrons, neutrons and protons. The atomic number of the elements represents the number of protons or electrons in a neutral atom. All known elements are arranged in a tabular form in increasing order of their atomic number that is called the periodic table.

The distribution of electrons in an atom can be shown with the help of electronic configuration. The electronic configuration of an element represents the number of electrons in different energy levels of an element.

Answer to Problem 2.97P

Sodium − ${\text{1s}}^{\text{2}}{\text{, 2s}}^{\text{2}}{\text{, 2p}}^{\text{6}}{\text{, 3s}}^{\text{1}}$ = 1 valence electron

Potassium- ${\text{1s}}^{\text{2}}{\text{, 2s}}^{\text{2}}{\text{, 2p}}^{\text{6}}{\text{, 3s}}^{\text{2}}{\text{, 3p}}^{\text{6}}{\text{, 4s}}^{\text{1}}$ = 1 valence electron

Chlorine - ${\text{1s}}^{\text{2}}{\text{, 2s}}^{\text{2}}{\text{, 2p}}^{\text{6}}{\text{, 3s}}^{\text{2}}{\text{, 3p}}^{\text{5}}$ = 7 valence electrons

Explanation of Solution

All the elements in the periodic table can be classified as metal, nonmetal and metalloid. In the periodic table, from group 1 to 12 are metals and nonmetals are placed from group 13 to 18. Metalloids are placed in between metals and nonmetals in the periodic table.

The periodic table can also divide on the basis of blocks as s, p, d and f-block elements. This classification is given on the basis of valence shell configuration of elements. The valence orbital of the element will determine the block of element. The electrons in the outermost orbital are called valence electrons. Hence the number of valence electrons is:

Sodium − ${\text{1s}}^{\text{2}}{\text{, 2s}}^{\text{2}}{\text{, 2p}}^{\text{6}}{\text{, 3s}}^{\text{1}}$ = 1 valence electron

Potassium- ${\text{1s}}^{\text{2}}{\text{, 2s}}^{\text{2}}{\text{, 2p}}^{\text{6}}{\text{, 3s}}^{\text{2}}{\text{, 3p}}^{\text{6}}{\text{, 4s}}^{\text{1}}$ = 1 valence electron

Chlorine - ${\text{1s}}^{\text{2}}{\text{, 2s}}^{\text{2}}{\text{, 2p}}^{\text{6}}{\text{, 3s}}^{\text{2}}{\text{, 3p}}^{\text{5}}$ = 7 valence electrons