Question

From the following list of elements \(-\mathrm{Ar}, \mathrm{H}, \mathrm{Ga}, \mathrm{Al}, \mathrm{Ca}\), \(\mathrm{Br}, \mathrm{Ge}, \mathrm{K}, \mathrm{O}-\) pick the one that best fits each description. Use each element only once: (a) an alkali metal, (b) an alkaline earth metal, (c) a noble gas, (d) a halogen, (e) a metalloid, (f) a nonmetal listed in group \(1 \mathrm{~A},(\mathrm{~g})\) a metal that forms a \(3+\) ion, \((\mathrm{h})\) a nonmetal that forms a \(2-\) ion, (i) an element that resembles aluminum.

Short answer

a) Potassium (K) b) Calcium (Ca) c) Argon (Ar) d) Bromine (Br) e) Germanium (Ge) f) Hydrogen (H) g) Aluminum (Al) h) Oxygen (O) i) Gallium (Ga)

Step-by-step solution

Alkali Metal

Alkali metals are found in Group 1 of the periodic table. The only element in the given list that belongs to Group 1 is: a) Potassium (K)

Alkaline Earth Metal

Alkaline Earth metals are found in Group 2 of the periodic table. The only element in the list that belongs to group 2 is: b) Calcium (Ca)

Noble Gas

Noble gases are found in Group 18 of the periodic table. The only element in the list that belongs to group 18 is: c) Argon (Ar)

Halogen

Halogens are found in Group 17 of the periodic table. The only element in the list that belongs to group 17 is: d) Bromine (Br)

Metalloid

Metalloids are elements that have properties between metals and non-metals. From the list of given elements, the only metalloid is: e) Germanium (Ge)

Nonmetal Listed in Group 1A

From the given elements, only Hydrogen (H) is a non-metal listed in Group 1A of the periodic table: f) Hydrogen (H)

Metal that forms 3+ Ion

From the list of elements, the metal that forms a 3+ ion is: g) Aluminum (Al)

Nonmetal that forms 2- Ion

From the list of elements, the nonmetal that forms a 2- ion is: h) Oxygen (O)

Element that resembles Aluminum

An element that resembles Aluminum in terms of properties is found in the same group of the periodic table, Group 13. From the given elements, the one that belongs to Group 13 is: i) Gallium (Ga)

Key concepts

Alkali Metals

Alkali metals, which take their place in the first group of the periodic table, are characterized by their highly reactive nature. This group includes lithium, sodium, potassium, rubidium, cesium, and francium. These metals are so reactive that they're not found in their elemental form in nature, but rather as compounds.

Students might find it easier to remember alkali metals as the 'shiny ones' that vigorously react with water to produce hydrogen gas and a hydroxide ion, which results in an alkaline solution. Because they have a single electron in their outermost shell, alkali metals eagerly lose that electron to achieve a stable, noble gas electron configuration. This makes them excellent conductors of electricity and highly malleable. Potassium (K) is an excellent example of an alkali metal that fulfills this criteria and was the correct answer in the exercise.

Alkaline Earth Metals

Located in the second group of the periodic table, alkaline earth metals include beryllium, magnesium, calcium, strontium, barium, and radium. These elements are named 'earth metals' because of their presence in earth's crust and 'alkaline' due to the basic nature of the oxides they form.

The metals in this family are shiny and possess two electrons in their outermost shell. They are less reactive than the alkali metals but will still react with water, albeit at a slower rate, to yield hydroxides and hydrogen gas. Since they have two electrons in their outer shell, they typically form +2 ions. For students working with exercises like the one given, remembering that calcium (Ca) is the classic example of an alkaline earth metal and the correct answer to part (b) can be of great help.

Noble Gases

Noble gases are a special group of elements seated majestically in Group 18 of the periodic table. They include helium, neon, argon, krypton, xenon, and radon. What's fascinating about these gases is that they are the least reactive of all elements.The reason behind their stoic nature lies in their full outer electron shell, which confers a stable configuration that doesn't need additional electrons nor willingly gives them away. They are colorless, odorless, and show a remarkable nonreactivity, which is why they're termed 'noble.' In lighting, noble gases are used for their glow - neon lights are perhaps the most famous application. Argon (Ar) is a stellar representation of noble gases and just the right answer for part (c) of the student's exercise.

Metalloids

Straddling the border between metals and nonmetals, metalloids exhibit a fascinating mix of properties that make them quite unique on the periodic table. These elements include boron, silicon, germanium, arsenic, antimony, tellurium, and polonium. They appear in the staircase-shaped region of the periodic table and possess properties of both neighboring groups.

Metalloids are semiconductors, meaning they can conduct electricity better than nonmetals but not as well as metals. This makes them incredibly valuable in electronics and computer chip manufacturing. To distinguish them in exercises, note that they have intermediate electrical conductivities and ionization energies. Germanium (Ge), chosen in the exercise, is the perfect example to discuss, being used in transistors and diodes, showcasing metalloid characteristics to the core.