Question

Based on the relationship between electron configurations and the periodic table, give the number of (a) outer-shell electrons in an atom of \(\mathrm{Sb} ;\) (b) electrons in the fourth principal electronic shell of \(\mathrm{Pt} ;\) (c) elements whose atoms have six outer-shell electrons; (d) unpaired electrons in an atom of Te; (e) transition elements in the sixth period.

Short answer

(a) Sb has 5 outer-shell electrons. (b) Pt has 14 electrons in its fourth principal electronic shell. (c) There are 5 elements with six outer-shell electrons: O, S, Se, Te and Po. (d) Te has 2 unpaired electrons. (e) There are 10 transition elements in the sixth period.

Step-by-step solution

Identifying outer-shell electrons in Sb

Antimony (Sb) is located in Group 15 of the periodic table, also called Nitrogen Group. Elements in this group have five outer-shell electrons in their ground state. Therefore, an atom of Sb has 5 outer-shell electrons.

Identifying electrons in the fourth principal electronic shell of Pt

Platinum (Pt) is located in Period 6 (6th row) and in the 10th column of the transition metals (d-block). The 4th principal shell corresponds to the 4th energy level, which includes the 4s, 4p, 4d, and 4f subshells. However, for Pt only the 4f subshell is relevant. The correct electronic configuration for Platinum is [Xe] 4f^14 5d^9 6s^1. Therefore, there are 14 electrons in the 4f subshell, which is the fourth principal electronic shell for Pt.

Identifying elements with six outer-shell electrons

Elements having six outer-shell electrons are found in Group 16 of the periodic table, also called the Oxygen Group or Chalcogens. These include Oxygen (O), Sulfur (S), Selenium (Se), Tellurium (Te), and Polonium (Po).

Identifying unpaired electrons in an atom of Te

Tellurium (Te) is in Period 5, Group 16 of the periodic table. The electronic configuration of Te is [Kr] 5s^2 4d^10 5p^4. The 5p subshell has four electrons where two are paired and two are unpaired. Therefore, Te has 2 unpaired electrons.

Identifying transition elements in the sixth period

Transition elements in the 6th period are transition metals found in the d-block of the 6th row of the periodic table. These include elements from Lanthanum (La) to Hafnium (Hf), and Rutherfordium (Rf) to Copernicium (Cn). If we exclude the Lanthanides series, there are 10 transition elements in the 6th period.

Key concepts

Electron Configuration

Electron configuration is the arrangement of electrons in an atom's electron shells. You'll find this concept closely tied to the periodic table's structure. Electrons occupy different energy levels or shells, which are further divided into subshells like s, p, d, and f. The distribution of electrons across these subshells follows a specific order based on increasing energy levels.

This arrangement is often depicted using notation, which begins with the nearest noble gas's electron configuration and follows with the additional electrons. For instance, the electron configuration of Platinum (Pt) is \[ \text{[Xe]}\ 4f^{14}\ 5d^9\ 6s^1 \]. Here, \text{[Xe]} represents the electron configuration of the noble gas Xenon, forming a "noble gas core," followed by additional electrons in higher energy subshells.

The electron configuration helps predict chemical properties and the atom's reactivity. It's especially crucial for understanding how atoms bond to form molecules.

Outer-Shell Electrons

Outer-shell electrons refer to the electrons located in the atom's outermost electron shell or energy level. These are also known as valence electrons. They play a vital role in determining how an element reacts with others, as most chemical reactions involve the transfer or sharing of these electrons.

For example, Antimony (Sb), which belongs to Group 15 of the periodic table, has five outer-shell electrons in its ground state. Outer-shell electrons are important because they are the ones involved in forming bonds during chemical reactions. Elements tend to gain, lose, or share electrons to achieve a stable electron configuration similar to the noble gases, usually having a full set of outer-shell electrons.

Groups in the periodic table are arranged so that elements with the same number of outer-shell electrons appear in the same column. This arrangement helps us quickly assess the reactivity and bonding potential of an element. Elements in Group 16, part of the Oxygen Group, have six outer-shell electrons, leading to this same property being shared amongst oxygen, sulfur, selenium, tellurium, and polonium.

Transition Elements

Transition elements are found in the d-block of the periodic table, specifically in the center section comprising Groups 3 to 12. These elements are known for their ability to form colorful compounds, variable oxidation states, and high melting points. Transition metals include common elements like iron, copper, and gold.

In particular, the sixth period of the periodic table includes transition metals from Lanthanum (La) to Hafnium (Hf) and resumes with Rutherfordium (Rf) to Copernicium (Cn), excluding the lanthanides. Transition metals are characterized by having partially filled d subshells, enabling them to exhibit diverse chemical behavior. For instance, the electronic configuration for platinum (Pt) ends with the filling of 5d and 6s subshells, typical of a d-block element.

These properties make transition elements valuable in many applications, such as catalysis, industrial processes, and the creation of alloys used in construction and manufacturing.