Problem 54 - Chemistry and Chemical Reactivity

Question

Reviewing the periodic table: (a) Name an element in Group 2 B. (b) Name an element in the fifth period. (c) Which element is in the sixth period in Group \(4 \mathrm{A} ?\) (d) Which element is in the third period in Group \(6 \mathrm{A} ?\) (e) Which alkali metal is in the third period? (f) Which noble gas element is in the fifth period? (g) Name the element in Group \(6 A\) and the fourth period. Is it a metal, nonmetal, or metalloid? (h) Name a metalloid in Group \(5 \mathrm{A}\).

Step-by-Step Solution

Answer

(a) Cadmium (Cd), (b) Rubidium (Rb) or any element through xenon (Xe), (c) Lead (Pb), (d) Sulfur (S), (e) Sodium (Na), (f) Xenon (Xe), (g) Selenium (Se; nonmetal), (h) Arsenic (As) or Antimony (Sb).

Step 1: Identify an element in Group 2 B

Group 2B consists of the transition metals which include the elements zinc (Zn), cadmium (Cd), and mercury (Hg).

Step 2: Identify an element in the fifth period

The fifth period of the periodic table starts with rubidium (Rb) and ends with xenon (Xe). Any element between Rb and Xe, inclusive, is in the fifth period.

Step 3: Identify the element in the sixth period and Group 4 A

In the sixth period and Group 4A is the element lead (Pb).

Step 4: Identify the element in the third period and Group 6 A

The element in the third period and Group 6A is sulfur (S).

Step 5: Identify the alkali metal in the third period

The alkali metals belong to Group 1, and the alkali metal in the third period is sodium (Na).

Step 6: Identify the noble gas element in the fifth period

In the fifth period, the noble gas is xenon (Xe). Noble gases belong to Group 18.

Step 7: Name the element in Group 6 A and fourth period and determine its type

Selenium (Se) is in Group 6A and the fourth period. It is classified as a nonmetal, though it has some properties of metalloids.

Step 8: Identify a metalloid in Group 5 A

In Group 5A, the metalloids present are arsenic (As) and antimony (Sb).

Key Concepts

Element Groups

The periodic table is organized into distinct columns known as element groups or families. Each group contains elements that share similar chemical properties. This similarity occurs because the elements in a group have the same number of valence electrons. Here are some examples of element groups:

• Alkali metals (Group 1): These are highly reactive metals, such as sodium (Na) and lithium (Li).
• Alkaline earth metals (Group 2): Less reactive than alkali metals, including elements like magnesium (Mg).
• Transition metals (Groups 3-12): These metals exhibit a wide range of oxidation states and include elements such as iron (Fe) and copper (Cu).
• Halogens (Group 17): Reactive nonmetals that form salts with metals, like chlorine (Cl) and fluorine (F).
• Noble gases: (Group 18): Inert, non-reactive gases including helium (He) and neon (Ne).

Element groups play a crucial role in understanding chemical reactivity and bonding. For instance, elements in Group 2B, like zinc (Zn), cadmium (Cd), and mercury (Hg), are part of the transition metals that tend to form complex ions.

Periods of Elements

Periods are the horizontal rows on the periodic table, each signifying the filling of a new electron shell. For example, the fifth period starts with rubidium (Rb) and ends with xenon (Xe), indicating that these elements have their fifth electron shell being filled. As you move across a period:

• The atomic number increases.
• Electrons fill into the same main energy level or shell.
• The properties of the elements change from metallic to non-metallic.

Understanding periods is important because it gives insight into the size, energy levels, and reactivity of elements. For instance, lead (Pb) is part of the sixth period, highlighting that it has more complex electron interactions due to additional filled shells compared to lighter elements.

Metals and Nonmetals

The periodic table divides elements into metals, nonmetals, and metalloids based on their physical and chemical properties. Metals tend to be conductive, malleable, and ductile. They also commonly have high melting and boiling points.

• Metals like sodium (Na) are often shiny and good conductors of heat and electricity.
• Nonmetals like sulfur (S) vary widely in their properties. They are generally poor conductors and can exist in various states of matter (solid, liquid, gas).

Interestingly, selenium (Se), found in Group 6A and the fourth period, is considered a nonmetal despite having some metalloid properties. It does not exhibit all the typical properties of metals or nonmetals, making its classification unique.

Metalloids

Metalloids have properties intermediate between metals and nonmetals and can be found on a "stair-step" line in the periodic table dividing the two types of elements. Some common features of metalloids include:

• They have a metallic appearance but are brittle and only fair conductors of electricity.
• They can behave as either metals or nonmetals depending on the conditions.

Examples of metalloids include silicon (Si), germanium (Ge), arsenic (As), and antimony (Sb), which are pivotal in electronics due to their semiconducting properties. Arsenic (As) and antimony (Sb), found in Group 5A, are crucial for understanding both chemical reactivity and electronic applications.