Ch.7 - Periodic Properties of the Elements

Problem 10

Chapter 7, Problem 10

The prefix eka- comes from the Sanskrit word for 'one.' Mendeleev used this prefix to indicate that the unknown element was one place away from the known element that followed the prefix. For example, eka-silicon, which we now call germanium, is one element below silicon. Mendeleev also predicted the existence of eka-manganese, which was not experimentally confirmed until 1937 because this element is radioactive and does not occur in nature. Based on the periodic table shown in Figure 7.1, what do we now call the element Mendeleev called eka-manganese?

Verified step by step guidance

Identify the position of manganese on the periodic table. Manganese is element number 25.

Understand the prefix 'eka-' used by Mendeleev, which indicates that the unknown element is one place below the known element in the periodic table.

Locate the element that is directly below manganese in the periodic table. This element will be in the same group but the next period.

Refer to the periodic table to find the atomic number of the element that is directly below manganese.

Identify the element by its atomic number and name, which is what Mendeleev referred to as eka-manganese.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Periodic Table

The periodic table is a systematic arrangement of elements based on their atomic number, electron configuration, and recurring chemical properties. Elements are organized in rows (periods) and columns (groups), which reflect their similarities. Understanding the layout of the periodic table is crucial for identifying relationships between elements, such as those predicted by Mendeleev.

Element Prediction

Element prediction refers to the process of inferring the existence of undiscovered elements based on trends observed in the periodic table. Mendeleev's use of the prefix 'eka-' exemplifies this, as he predicted elements like eka-silicon and eka-manganese by identifying gaps in the table. This concept highlights the predictive power of the periodic table in understanding elemental properties.

Radioactivity

Radioactivity is the process by which unstable atomic nuclei lose energy by emitting radiation. This phenomenon is significant in the context of elements like eka-manganese, which is now known as technetium. Understanding radioactivity is essential for recognizing why certain elements may not be found in nature and how they can be synthesized in laboratories.

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Related Practice

Textbook Question

In the following reaction

which sphere represents a metal and which represents a nonmetal?

Shown below is a qualitative diagram of the atomic orbital energies for an Na atom. The number of orbitals in each subshell is not shown.

(d) A sodium vapor lamp (Figure 7.23) operates by using electricity to excite the highest-energy electron to the next highest-energy level. Light is produced when the excited electron drops back to the lower level. Which two energy levels are involved in this process for the Na atom?

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Open Question

(a) Evaluate the expressions 2 * 1, 2 * 11 + 32, 2 * 11 + 3 + 52, and 2 * 11 + 3 + 5 + 72. How do the atomic numbers of the noble gases relate to the numbers? (b) What topic discussed in Chapter 6 is the source of the number '2' in the expressions in part (a)?

Open Question

Moseley’s experiments on X rays emitted from atoms led to the concept of atomic numbers. (a) If arranged in order of increasing atomic mass, which element would come after chlorine? (b) Describe two ways in which the properties of this element differ from the other elements in group 8A.

Textbook Question

Among the elements N, O, P, and S, which element or elements have the smallest effect nuclear charge if we use Equation 7.1 to calculate Zeff? Which element or elements have the largest effective nuclear charge?

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Textbook Question

Which of the following statements about effective nuclear charge for the outermost valence electron of an atom is incorrect? (i) The effective nuclear charge can be thought of as the true nuclear charge minus a screening constant due to the other electrons in the atom. (ii) Effective nuclear charge increases going left to right across a row of the periodic table. (iii) Valence electrons screen the nuclear charge more effectively than do core electrons. (iv) The effective nuclear charge shows a sudden decrease when we go from the end of one row to the beginning of the next row of the periodic table. (v) The change in effective nuclear charge going down a column of the periodic table is generally less than that going across a row of the periodic table

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