Question

Identify the group number corresponding to each of the following families of elements: (a) alkali metals (b) alkaline earth metals (c) halogens (d) noble gases

Short answer

(a) Group 1, (b) Group 2, (c) Group 17, (d) Group 18.

Step-by-step solution

Identify Alkali Metals

Alkali metals are elements found in Group 1 of the periodic table. These elements include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

Identify Alkaline Earth Metals

Alkaline earth metals are elements found in Group 2 of the periodic table. These elements include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

Identify Halogens

Halogens are elements found in Group 17 of the periodic table. The halogens include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

Identify Noble Gases

Noble gases are elements found in Group 18 of the periodic table. These elements include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).

Key concepts

Alkali Metals

Alkali metals are a fascinating group of elements found in Group 1 of the periodic table. This family includes lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). They are known for being highly reactive, especially with water. This high reactivity is due to their single valence electron, which they readily lose to achieve a stable electron configuration.
Some interesting characteristics of alkali metals include:

• They are soft and can often be cut with a knife.
• When exposed to air, they tarnish quickly due to oxidation.
• They have low melting points compared to most other metals.
• Alkali metals are excellent conductors of electricity.

Because of their reactivity, alkali metals are never found in their pure form in nature. They are always bonded with other elements.

Alkaline Earth Metals

Alkaline earth metals are located in Group 2 of the periodic table and include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). These metals are characterized by having two electrons in their outer electron shell, making them slightly less reactive than alkali metals. However, they still form compounds easily, especially with halogens to form salts.
Key properties of alkaline earth metals are:

• They are shiny and silvery-white in appearance.
• They have higher melting and boiling points than alkali metals.
• These elements form ionically bonded compounds with nonmetals.
• They are good conductors of electricity.

In nature, alkaline earth metals are typically found in mineral compounds rather than in their elemental form due to their reactivity with other elements.

Halogens

Halogens are elements found in Group 17 of the periodic table. This group includes fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). Halogens are well-known for their ability to form salts when combined with metals, a trait reflected in their name, which means 'salt-former.'
The following are some notable properties of halogens:

• They have seven valence electrons, which makes them very reactive as they seek to gain an additional electron to reach a stable octet.
• Halogens are generally found in different states of matter: gases, liquids, and solids.
• They are known for their strong, unpleasant odors and are highly toxic in their elemental form.
• Halogens have high electronegativity and high electron affinity.

Due to their reactivity, halogens are not found freely in nature and usually exist as halide ions or as part of molecular compounds.

Noble Gases

Noble gases are found in Group 18 of the periodic table. They include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Known for their lack of reactivity, they are often referred to as inert gases because their outer electron shell is full, making them stable and unlikely to form bonds with other elements.
Key characteristics of noble gases include:

• They are colorless, odorless, and tasteless.
• They exhibit very low boiling and melting points as they are gases at room temperature.
• Noble gases are used in applications where inert atmospheres are needed, such as in light bulbs or welding.
• They are nonflammable and nonreactive under most conditions.

Due to their stability, noble gases are often found in their elemental form rather than as part of compounds, which sets them apart from many other elements on the periodic table.