Question

Identify the group 6 A element that best fits each of the following descriptions: (a) Is the most electronegative (b) Is a semimetal (c) Is radioactive (d) Is the most abundant element in the Earth's crust

Short answer

(a) Oxygen; (b) Tellurium; (c) Polonium; (d) Oxygen.

Step-by-step solution

Identify Group 16 Elements

Group 6A elements (Group 16 in modern terms) of the periodic table are Oxygen (O), Sulfur (S), Selenium (Se), Tellurium (Te), and Polonium (Po). These elements have unique properties that correspond to the descriptions given.

Determine the Most Electronegative Element

In the periodic table, electronegativity usually increases from left to right across a period and decreases down a group. Oxygen (O) is in the top position of Group 6A, making it the most electronegative element in this group.

Identify the Semimetal

Semimetals, or metalloids, have properties intermediate between metals and non-metals. Tellurium (Te) is considered a semimetal in Group 6A.

Find the Radioactive Element

Polonium (Po) is known to be the only naturally occurring radioactive element in Group 6A. It has no stable isotopes, meaning it is intrinsically radioactive.

Determine the Most Abundant Element in Earth's Crust

Oxygen (O) is the most abundant element in the Earth’s crust, making up a significant percentage by weight of the crust.

Key concepts

Electronegativity

Electronegativity is a measure of how strongly an atom can attract and hold onto electrons. It is an important concept in chemistry as it influences how atoms bond with each other, forming compounds.

• In the periodic table, electronegativity increases as you move from left to right across a period, and it decreases as you move down a group.
• This trend occurs because, as you go across a period, the number of protons in the nucleus increases, pulling electrons more strongly.
• Going down a group adds more electron shells, which can shield outer electrons from the nucleus, weakening the attraction.

For Group 16 elements, Oxygen sits at the top, making it the most electronegative member of the group.
Its high electronegativity is why oxygen is such a reactive element, forming bonds with numerous elements.

Semimetals

Semimetals, or metalloids, exhibit properties that are intermediate between those of metals and nonmetals.

• They can conduct electricity better than nonmetals but worse than metals, which makes them useful in electronics.
• Most metalloids generally have a metallic appearance but are brittle and not malleable like metals.

Tellurium, part of Group 16, is a classic example of a semimetal. It features an ability to conduct electricity that lies between metals and nonmetals, making it useful in certain electronics. Its unique characteristics allow it to play significant roles in various industries, despite its place as a relatively rare element.

Radioactive Elements

Radioactive elements spontaneously emit particles or radiation as their unstable nuclei break down to achieve stability. This process is called radioactivity.

• Many elements have radioactive isotopes, but only a select few are naturally radioactive in their entire form.
• Polonium is the only naturally occurring radioactive element in Group 16.
• It has no stable isotopes, meaning all its isotopes undergo radioactive decay.

Polonium's radioactivity is used in applications that require heat but also carries great risks due to its intense radiation. It's important in industries but needs careful handling.

Abundance in Earth's Crust

The abundance of elements in Earth's crust refers to the relative percentages of each element compared to the total mass of the crust.

• Oxygen is the most abundant element in Earth's crust, constituting almost half of its weight.
• It is fundamental to the formation of minerals and types of rocks, as most compounds in the crust are oxides.

Oxygen's omnipresence contributes significantly to the composition and behavior of Earth's crust. Its high electronegativity and reactivity enable it to bond with almost all elements, forming essential compounds such as oxides and silicates. These compounds are crucial to geological formations and processes and have a profound impact on the planet's ecosystem.