Question

Which of the following is (a) an alkali metal? Ca, \(\mathrm{Cu}\), In, \(\mathrm{Li}, \mathrm{S}\) (b) a halogen? Ce, \(\mathrm{Hg}, \mathrm{Si}, \mathrm{O}, \mathrm{I}\) (c) a transition element? \(\mathrm{Pb}, \mathrm{W}, \mathrm{Ca}, \mathrm{Cs}, \mathrm{P}\) (d) a noble gas? \(\mathrm{Xe}, \mathrm{Se}, \mathrm{H}, \mathrm{Sr}, \mathrm{Zr}\) (e) a lanthanide element? \(\mathrm{Th}, \mathrm{Sm}, \mathrm{Ba}, \mathrm{F}, \mathrm{Sb}\) (f) an actinide element? Ho, \(\mathrm{Mn}, \mathrm{Pu},\) At, \(\mathrm{Na}\) (g) an alkaline earth metal? \(\mathrm{Mg}, \mathrm{Fe}, \mathrm{K}, \mathrm{Cl}, \mathrm{Ni}\)

Short answer

The answers are: (a) Li, (b) I, (c) W, (d) Xe, (e) Sm, (f) Pu, (g) Mg.

Step-by-step solution

Identify Alkali Metals

Alkali metals are located in Group 1 of the periodic table and possess a single valence electron, with the configuration s1. The elements in the list that match this criteria are Lithium (Li).

Locate Halogens

Halogens are elements found in Group 17 of the periodic table and are characterized by having seven valence electrons, with the configuration p5. From the list provided, Iodine (I) is a halogen.

Define Transition Elements

Transition elements are located in groups 3 through 12 on the periodic table and are d-block elements which can use the inner d-electron shell in bonding. Tungsten (W) is a transition element from the given options.

Identify Noble Gases

Noble gases are found in Group 18 and have a complete valence shell, typically with the configuration p6 (except for Helium which is s2). Xenon (Xe) is the noble gas in the provided list.

Determine Lanthanide Elements

Lanthanide elements belong to the f-block and include the 14 elements following Lanthanum. They are characterized by filling the 4f orbital. Samarium (Sm) is the lanthanide element from the options given.

Pick Out Actinide Elements

Actinide elements are also part of the f-block and consist of the 15 elements starting from Actinium. These elements are known for filling the 5f orbital. Plutonium (Pu) is the actinide element in the list.

Identify Alkaline Earth Metals

Alkaline earth metals are found in Group 2 and have two valence electrons, with the electron configuration of s2. Among the given elements, Magnesium (Mg) fits this category.

Key concepts

Alkali Metals

Alkali metals represent the very first group on the periodic table and include familiar elements like Sodium (a, and Potassium (a. These metals are highly reactive, particularly with water, due to their single valence electron, which they easily donate to form positive ions or cations. Lithium (a), from the provided exercise, is a classic example of an alkali metal with its electron configuration ending in s1, making it eager to participate in chemical reactions.

In everyday life, alkali metals have various uses, such as in batteries (Lithium), streetlights (Sodium), and even as essential nutrients in biochemistry (Potassium). However, their reactivity also means they must be handled with care, generally stored under oil to prevent reactions with air or moisture.

Halogens

Occupying Group 17 of the periodic table, halogens are known for their electronegativity and reactivity, especially with alkali and alkaline earth metals. This group of nonmetals includes Fluorine, Chlorine, Bromine, Iodine, and Astatine. In the given exercise, Iodine (a) is the halogen, recognized for its seven valence electrons and its tendency to form negative ions or anions.

Due to their reactivity, halogens have a wide range of applications, from disinfectants and bleach (Chlorine), to antiseptics (Iodine), and even in pharmaceuticals and chemical synthesis. It's fascinating to observe their distinct colors and states at room temperature, from gases (Chlorine) to liquids (Bromine) to solids (Iodine).

Transition Elements

Transition elements, found between groups 3 and 12 of the periodic table, are metals with the unique ability to use their inner d-shell electrons for bonding, resulting in a variety of oxidation states and colored compounds. Tungsten (a), the example given, is well-known for its high melting point and strength, which makes it ideal for lightbulb filaments and steel alloys.

These elements play critical roles in technology, biology, and industry. For instance, Iron is vital for blood's oxygen-carrying capacity, while elements like Platinum are integral for catalytic converters in cars. The variable oxidation states of transition metals also make them fascinating for chemists, especially in catalysis and electronic structures.

Noble Gases

In Group 18 of the periodic table, you'll find the noble gases, which include Helium, Neon, Argon, Krypton, Xenon, and Radon. These elements are notorious for their lack of chemical reactivity, owing to their filled valence shells and stable configurations. Xenon (a), the noble gas in our exercise, stands out for its ability to form compounds under extreme conditions, unlike other members of this group.

Noble gases are fascinating for their uses in lighting and temperature control. For example, Helium is used in cryogenics and as a shielding gas for welding, while Neon lights up vivid advertising signs. They remind us that even the most inert elements can have a lively impact on our daily lives.

Lanthanide Series

The Lanthanide series encompasses 15 metallic elements, from Cerium to Lutetium, nestled in the f-block of the periodic table. Known for their magnetic and phosphorescent properties, Lanthanides, like Samarium (a) identified in the exercise, are instrumental in many high-tech applications.

These elements are often found in smartphones, green technology, and even medical imaging. The subtleties of their 4f electron shell filling give each lanthanide unique characteristics, such as varying degrees of magnetism or different colors in compounds. Their rarity and challenge to extract underscore the importance of recycling electronics to recover these valuable materials.

Actinide Series

Just below the lanthanides are the Actinide series, also part of the f-block. This series includes radioactive elements, which makes them both intriguing for scientific research and important in nuclear energy. Plutonium (a), cited from the problem, is just one example of these heavy, dense metals. While most are synthetic, their properties are crucial for the fields of nuclear power and radiomedicine.

Discoveries within the actinide series have propelled advancements in energy generation, like Uranium used in nuclear reactors. However, the radioactivity of these elements also presents challenges for storage and safety, demanding responsible handling and innovative solutions for waste management.

Alkaline Earth Metals

Situated in Group 2 of the periodic table, the alkaline earth metals include Beryllium, Magnesium, Calcium, Strontium, Barium, and Radium. They all possess two electrons in their outer shell, giving them a stable configuration of s2. Magnesium (a), from our list, is widely utilized for its combination of lightness and strength, making it ideal for construction and transportation.

Alkaline earth metals are cornerstones in various industries, from creating strong yet lightweight materials (Magnesium) to serving as a key component in fireworks and flares (Strontium and Barium). While less reactive than alkali metals, they still react with water to form hydroxides and with halogens to form salts, showcasing the diversity of the periodic table's elements and their reactions.