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Ch.7 - Periodic Properties of the Elements
All textbooksBrown 15th EditionCh.7 - Periodic Properties of the ElementsProblem 55
Chapter 7, Problem 55

(a) Does metallic character increase, decrease, or remain unchanged as one goes from left to right across a row of the periodic table? (b) Does metallic character increase, decrease, or remain unchanged as one goes down a column of the periodic table?

Verified step by step guidance
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Step 1: Understand the concept of metallic character. Metallic character refers to the tendency of an element to lose electrons and form positive ions (cations). Elements with high metallic character are typically good conductors of electricity and heat, have a shiny appearance, and are malleable and ductile.
Step 2: Analyze the trend across a period (row) in the periodic table. As you move from left to right across a period, elements generally become less metallic. This is because the number of protons in the nucleus increases, which leads to a stronger attraction between the nucleus and the electrons, making it harder for the atoms to lose electrons.
Step 3: Analyze the trend down a group (column) in the periodic table. As you move down a group, the metallic character generally increases. This is because the atomic size increases, and the outer electrons are further from the nucleus, which reduces the effective nuclear charge experienced by these electrons, making it easier for the atoms to lose electrons.
Step 4: Relate these trends to specific examples. For instance, in the second period, lithium (Li) is more metallic than beryllium (Be), and in the alkali metal group, lithium (Li) is less metallic than cesium (Cs).
Step 5: Summarize the trends. Across a period, metallic character decreases from left to right. Down a group, metallic character increases. These trends are due to changes in atomic size and effective nuclear charge.

Key Concepts

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

Metallic Character

Metallic character refers to the set of properties typically associated with metals, including conductivity, malleability, ductility, and luster. Elements with high metallic character tend to lose electrons easily, forming positive ions. This property is influenced by an element's position in the periodic table, which affects its atomic structure and behavior.
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Periodic Trends

Periodic trends are predictable patterns observed in the periodic table, such as atomic radius, ionization energy, and electronegativity. As one moves from left to right across a period, elements generally become less metallic due to increasing nuclear charge, which attracts electrons more strongly. Conversely, moving down a group, atomic size increases, often leading to a greater metallic character.
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Effective Nuclear Charge

Effective nuclear charge (Z_eff) is the net positive charge experienced by an electron in a multi-electron atom. It accounts for the shielding effect of inner electrons, which reduces the full nuclear charge felt by outer electrons. As Z_eff increases across a period, the attraction between the nucleus and valence electrons strengthens, leading to a decrease in metallic character.
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Related Practice
Textbook Question

Consider the following equation:


Ca+(𝑔)+e−⟶Ca(𝑔)

Which of the following statements are true?


i. The energy change for this process is the electron affinity of the Ca+ ion.

ii. The energy change for this process is the negative of the first ionization energy of the Ca atom.

iii. The energy change for this process is the negative of the electron affinity of the Ca atom.

a. Only statement i is true.

b. Only statement ii is true.

c. Only statement iii is true.

d. Only statements i and ii are true.

e. All three statements are true.

Textbook Question

True or false: Because elements that form cations are metals, and elements that form anions are nonmetals, elements that do not form ions are metalloids.