Ch.5 - Periodicity & Electronic Structure of Atoms

McMurry8th EditionChemistryISBN: 9781292336145Not the one you use?Change textbook

McMurry 8th Edition

Ch.5 - Periodicity & Electronic Structure of Atoms

Problem 121

Chapter 5, Problem 121

Order the following atoms according to increasing atomic radius: Rb, Cl, As, K.

Verified step by step guidance

Identify the periodic trend for atomic radius: Atomic radius generally increases as you move down a group and decreases as you move across a period from left to right.

Locate each element on the periodic table: Rb (Rubidium) and K (Potassium) are in Group 1, Cl (Chlorine) is in Group 17, and As (Arsenic) is in Group 15.

Compare elements within the same group: Rb and K are in the same group, with Rb below K, so Rb has a larger atomic radius than K.

Compare elements across periods: Cl is in Period 3, As is in Period 4, K is in Period 4, and Rb is in Period 5. Elements in higher periods generally have larger atomic radii.

Order the elements by increasing atomic radius: Start with the smallest atomic radius and proceed to the largest based on their positions in the periodic table.

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Key Concepts

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

Atomic Radius

Atomic radius is a measure of the size of an atom, typically defined as the distance from the nucleus to the outermost electron shell. It varies across the periodic table, generally increasing down a group due to the addition of electron shells and decreasing across a period due to increased nuclear charge, which pulls electrons closer to the nucleus.

Periodic Trends

Periodic trends refer to the predictable patterns observed in the properties of elements as you move across or down the periodic table. For atomic radius, the trend shows that elements in the same group have larger radii as you go down, while elements in the same period have smaller radii as you move from left to right due to effective nuclear charge.

Group and Period Positioning

The position of an element in the periodic table, defined by its group (vertical column) and period (horizontal row), significantly influences its atomic radius. For instance, rubidium (Rb) and potassium (K) are in Group 1 and have larger atomic radii compared to chlorine (Cl) and arsenic (As), which are in Groups 17 and 15, respectively, leading to a clear ordering based on their positions.

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Related Practice

Textbook Question

Why do atomic radii decrease from left to right across a period of the periodic table?

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Textbook Question

Fill in the blanks with the appropriate region of electromagneticradiation: UV, visible, infrared.(a) The Sun most strongly emits in the _____ and regions of electromagnetic radiation(b) The atmosphere filters out biologically damaging ______radiation from incoming solar radiationand prevents it from reaching Earth.(c) The Earth most strongly emits ______ radiation.(d) Greenhouse gases absorb _______ radiation.

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Textbook Question

Why do the Earth and Sun have different emission spectra?

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Textbook Question

Orbital energies in single-electron atoms or ions, such as He+, can be described with an equation similar to the Balmer–Rydberg equation:

where Z is the atomic number. What wavelength of light in nanometers is emitted when the electron in He+ falls from n = 3 to n = 2?

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Textbook Question

Imagine a universe in which the four quantum numbers can have the same possible values as in our universe except that the angular-momentum quantum number l can have integral values of 0, 1, 2...n + 1 (instead of 0, 1, 2..., n - 1). (a) How many elements would be in the first two rows of the periodic table in this universe?

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