Problem 32 - Chemistry Matter and Change

Question

Match each item on the left with its corresponding group on the right. Identify each of the following as a metal, a nonmetal, or a metalloid. \(\begin{array}{ll}{\text { a. alkali metals }} & {\text { 1. group } 18} \\\ {\text { b. halogens }} & {\text { 2. group } 1} \\ {\text { c. alkaline earth metals }} & {\text { 3. group } 2} \\ {\text { d. noble gases }} & {\text { 4. group } 17}\end{array}\)

Step-by-Step Solution

Answer

a - 2, b - 4, c - 3, d - 1

Step 1: Identify Group for Alkali Metals

Alkali metals are found in group 1 of the periodic table. Common examples include lithium (Li), sodium (Na), and potassium (K).

Step 2: Identify Group for Alkaline Earth Metals

Alkaline earth metals are found in group 2 of the periodic table. This group includes elements like beryllium (Be), magnesium (Mg), and calcium (Ca).

Step 3: Identify Group for Halogens

Halogens are in group 17 of the periodic table. This group consists of fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

Step 4: Identify Group for Noble Gases

Noble gases are located in group 18 of the periodic table. This group includes helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).

Step 5: Match Each Term with Its Group

Based on the identification: - Alkali metals (a) match with group 2. - Halogens (b) match with group 4. - Alkaline earth metals (c) match with group 3. - Noble gases (d) match with group 1.

Key Concepts

Alkali Metals

Alkali metals are fascinating elements found in Group 1 of the periodic table. They include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). This family of metals is characterized by their shiny appearance and high reactivity, especially with water.
One remarkable property of alkali metals is their softness. You can literally cut them with a knife! Because they have only one electron in their outer shell, they are eager to lose it to achieve a stable noble gas configuration. This is what makes them so reactive. When exposed to water, alkali metals form alkaline hydroxides and release hydrogen gas. For example, sodium reacts with water to form sodium hydroxide (\[2Na + 2H_2O \rightarrow 2NaOH + H_2\]).

• Highly reactive, stored under oil to prevent reactions.
• Soft and can be cut with a knife.
• Common examples include lithium, sodium, and potassium.

Alkaline Earth Metals

In Group 2 of the periodic table, you'll find the alkaline earth metals. These metals—beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra)—are slightly less reactive than their Group 1 neighbors. They tend to be denser and harder as well.
Alkaline earth metals have two electrons in their outer shell, which they readily lose to achieve a stable electron configuration. This characteristic makes them reactive, though not as intensely as alkali metals. For instance, magnesium reacts with steam to form magnesium oxide and hydrogen gas, shown in the equation:\[ Mg + 2H_2O \rightarrow Mg(OH)_2 + H_2 \] .
They form ionic compounds, and some of these, like calcium carbonate, are essential for life on Earth.

• Contain two electrons in their outermost shell.
• Include elements like magnesium and calcium.
• Have higher melting points compared to alkali metals.

Halogens

Halogens are the nonmetals that make up Group 17 of the periodic table, consisting of fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). They are incredibly reactive, especially with alkali and alkaline earth metals, to form salts. The term "halogen" actually means "salt-former.”
These elements need only one electron to achieve the stable configuration of a noble gas, giving them a strong tendency to gain electrons during chemical reactions. For instance, chlorine combines with sodium to form table salt:\[ 2Na + Cl_2 \rightarrow 2NaCl \] .
Halogens exist in various physical states—fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid at room temperature.

• Very reactive nonmetals.
• Exist in all three physical states at room temperature.
• Form salts when combined with metals.

Noble Gases

Noble gases are located in Group 18, the far right of the periodic table. This group includes helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). They are known for being colorless, odorless, and generally nonreactive.
Their stability comes from having complete electron shells, which make them largely unreactive. Due to this inertness, they are often used in areas requiring non-reactive conditions. For example, argon is commonly used in light bulbs to prevent the tungsten filament from reacting with oxygen.
Noble gases do play crucial roles; helium, being lighter than air, is used in balloons, and xenon finds use in various advanced lighting systems.

• Nonreactive due to full valence shells.
• Include familiar elements like helium and neon.
• Used in lighting and other industrial applications.

Metals Nonmetals Metalloids

The periodic table is broadly segmented into metals, nonmetals, and metalloids. Metals are typically good conductors of electricity and heat, and they often have a shiny appearance. Found on the left side and center of the periodic table, metals include elements such as iron (Fe), copper (Cu), and zinc (Zn).
Nonmetals, located on the right side of the table, are generally poor conductors and can be gases, liquids, or brittle solids. Common examples include oxygen (O), nitrogen (N), and sulfur (S). Metalloids possess properties intermediate between metals and nonmetals, and are positioned along the zig-zag line on the table.
They can be semi-conductors, which makes them invaluable in the electronics industry. Silicon (Si) and germanium (Ge) are two well-known metalloids used in making computer chips.

• Metals are conductive and malleable.
• Nonmetals are insulators with varying states at room temperature.
• Metalloids have properties between metals and nonmetals, crucial for electronics.