Question

According to general trends in the periodic table, predict which element in each of the following pairs has greater metallic character: (a) \(\mathrm{B}\) or \(\mathrm{Al}\) (b) Na or K (c) \(\mathrm{Mg}\) or Ba (d) \(\mathrm{H}\) or \(\mathrm{Fe}\)

Short answer

(a) Aluminum (Al), (b) Potassium (K), (c) Barium (Ba), (d) Iron (Fe)

Step-by-step solution

Understanding Metallic Character

Metallic character refers to how easily an atom can lose electrons, a characteristic of metals. In the periodic table, metallic character increases as you move down a group and decreases as you move across a period from left to right.

Analyzing Pair (a) - Boron ( B) vs. Aluminum ( Al)

Boron ( B) and Aluminum ( Al) belong to Group 13 of the periodic table. Since metallic character increases down a group, aluminum, being below boron, has a greater metallic character than boron.

Analyzing Pair (b) - Sodium (Na) vs. Potassium (K)

Sodium (Na) and Potassium (K) are both in Group 1. Moving down the group from Na to K, the metallic character increases. Thus, potassium has a greater metallic character than sodium.

Analyzing Pair (c) - Magnesium ( Mg) vs. Barium ( Ba)

Magnesium ( Mg) and Barium ( Ba) fall in Group 2. Barium is found below magnesium in the periodic table, indicating it has a greater metallic character than magnesium.

Analyzing Pair (d) - Hydrogen ( H) vs. Iron ( Fe)

Hydrogen ( H) is a non-metal, whereas Iron ( Fe) is a transition metal. In general, metals have a greater metallic character than non-metals. Therefore, iron has a greater metallic character than hydrogen.

Key concepts

Periodic Table Trends

The periodic table is a structured map of chemical elements, arranged by their atomic number, electron configuration, and recurring chemical properties. One of the fascinating aspects of the periodic table is the predictable trends it exhibits. These trends help us understand and predict how elements behave in relation to one another. For example, properties such as atomic radius, electronegativity, and metallic character often change in a predictable manner through the table.

• As you move from left to right across a period (row), elements become less metallic.
• Metallic character tends to increase as you move down a group (column).
• This is because electrons are more easily lost to form positive ions in elements that are more metallic.

Understanding these trends is key to predicting elements' chemical behaviors and interactions.

Metallic Properties

In chemistry, metallic properties refer to the ability of an element to exhibit characteristics typical of metals. This includes attributes like luster, ductility, malleability, and good electrical and thermal conductivity. At the atomic level, metallic properties are associated with the ability of atoms to lose electrons and form cations easily.
Here are some key points about metallic properties:

• Metals tend to lose electrons to achieve a stable electron configuration, often resembling the nearest noble gas.
• Metals are shiny due to their free electrons' ability to reflect light.
• They conduct electricity because their delocalized electrons can move freely through the lattice structure.
• Metals include elements found in the s-block, d-block, and f-block of the periodic table, except for hydrogen which is a non-metal.

Recognizing these properties can help in predicting how different elements might combine or react under certain conditions.

Group and Period Trends in Elements

The elements in the periodic table show various trends in their properties both within a group and across a period. These trends are crucial to understanding element behavior and help us predict reactions and compounds.

Group Trends:

• In a group, elements exhibit a gradual change in properties as you move from top to bottom.
• The atomic radius increases because new electron shells are added.
• Ionization energy decreases due to the increased distance of valence electrons from the nucleus.
• As metallic character increases in a group, elements tend to become more reactive metals.

Period Trends:

• Across a period from left to right, the atomic radius generally decreases due to the increase in nuclear charge pulling electrons tighter.
• Ionization energy increases as more energy is required to remove an electron.
• Non-metallic character and electronegativity increase as we move toward the right side of the period.
• Metallic character diminishes as elements tend to gain electrons to form anions.

Being aware of these trends allows chemists and students alike to understand how elements might behave in various chemical contexts and how they compare with one another.