Question

Give two examples of each of the following: (a) alkali metals, (b) alkaline earth metals, (c) halogens. (d) noble gases, (e) chalcogens, (f) transition metals.

Short answer

Examples: (a) Li, Na; (b) Be, Mg; (c) F, Cl; (d) He, Ne; (e) O, S; (f) Fe, Cu.

Step-by-step solution

Understand the Groups

Familiarize yourself with the periodic table groups that correspond to the categories mentioned in the exercise. This involves knowing which elements belong to alkali metals, alkaline earth metals, halogens, noble gases, chalcogens, and transition metals. For instance, alkali metals are found in Group 1, and alkaline earth metals in Group 2.

Identify Alkali Metals

Alkali metals are located in Group 1 of the periodic table. The first two elements in this group, which are examples, are Lithium (Li) and Sodium (Na).

Identify Alkaline Earth Metals

Alkaline earth metals are located in Group 2 of the periodic table. Examples include Beryllium (Be) and Magnesium (Mg).

Identify Halogens

Halogens are in Group 17 of the periodic table. The first two elements in this group are Fluorine (F) and Chlorine (Cl).

Identify Noble Gases

Noble gases are found in Group 18 of the periodic table. Examples include Helium (He) and Neon (Ne).

Identify Chalcogens

Chalcogens are located in Group 16 of the periodic table. The elements Oxygen (O) and Sulfur (S) are examples of chalcogens.

Identify Transition Metals

Transition metals span groups 3 to 12 on the periodic table. Iron (Fe) and Copper (Cu) are classic examples of transition metals.

Key concepts

Alkali Metals

Alkali metals represent a group of elements located in Group 1 of the periodic table. This group includes highly reactive metals like Lithium (Li) and Sodium (Na). These metals have a single electron in their outermost shell, which makes them eager to lose that electron in order to achieve a stable, noble gas electron configuration.

The reactivity of alkali metals increases down the group. This means that sodium is more reactive than lithium, while potassium and further down the group, elements like cesium, are even more reactive. Some key characteristics of alkali metals include:

• Softness and can often be cut with a knife
• Low density, with lithium, sodium, and potassium able to float on water
• Low melting points compared to most other metals
• Their bright metallic luster and excellent conductivity for heat and electricity

Due to their high reactivity, especially with water, alkali metals are typically stored under oil to prevent unwanted reactions.

Alkaline Earth Metals

Alkaline earth metals are found in Group 2 of the periodic table and include elements like Beryllium (Be) and Magnesium (Mg). While these metals are also reactive, they are somewhat less reactive compared to alkali metals.

Each alkaline earth metal possesses two electrons in its outermost shell, making them eager to lose both in order to achieve stability. Some of the common properties of alkaline earth metals include:

• Being harder than alkali metals with higher melting points
• Having densities that vary but are generally more than alkali metals
• Reacting with water, though not as violently as alkali metals
• Combining to form a variety of useful compounds, such as magnesium oxide and calcium carbonate

These elements form important compounds and play vital roles in processes and industries, such as manufacturing and construction.

Halogens

The halogens are a group of non-metals located in Group 17 of the periodic table. They include Fluorine (F) and Chlorine (Cl), known for their reactive nature. Halogens possess seven electrons in their outer shells, needing just one more to achieve a complete and stable configuration, similar to noble gases.

These elements are highly reactive, especially with alkali and alkaline earth metals, forming salts and other compounds. Important properties and applications of halogens include:

• Existence in different states at room temperature, e.g., fluorine and chlorine are gases
• Formation of ionic and covalent bonds in various compounds
• Utilization in disinfection, such as chlorine in water treatment
• Involvement in making compounds with anti-septic and refrigerant properties

Due to their high reactivity, handling halogens requires careful measures and safety protocols.

Noble Gases

Noble gases, occupying Group 18, are known for their inertness and include Helium (He) and Neon (Ne). These gases have full valence electron shells, making them extremely stable and unreactive under normal conditions.

Noble gases play significant roles in various applications due to their unique properties:

• Colorless, odorless, and non-flammable characteristics
• Safe as they do not participate in ordinary chemical reactions
• Use in lighting and signage, as neon lights
• Application as inert atmospheres needed in industrial processes to prevent reactions

These gases are crucial for industries and technologies that demand non-reactive environments or illumination.

Chalcogens

Chalcogens are found in Group 16 of the periodic table and include elements like Oxygen (O) and Sulfur (S). These elements have six electrons in their outer shell, which means they tend to gain or share two electrons to achieve a full set of valence electrons.

Chalcogens are essential to life and have a range of uses:

• Oxygen is crucial for respiration in living organisms
• Sulfur is key in industrial processes, such as producing sulfuric acid
• Chalcogens can form a variety of oxides and sulfides, used in different chemical reactions
• Presence in large abundance in the earth’s crust and atmosphere

The versatility and abundance of chalcogens make them integral to biological and industrial functions.

Transition Metals

Transition metals span groups 3 through 12 on the periodic table and include elements like Iron (Fe) and Copper (Cu). These metals are characterized by their ability to form a wide variety of chemical compounds due to their variable oxidation states.

Unlike other groups, transition metals are known for:

• High melting and boiling points
• Distinctive, often vibrant colors when part of compounds
• Excellent conductors of heat and electricity
• Mechanical properties, making them both strong and malleable

They are essential in construction, electricity, and plumbing, and their compounds are used across industries for dyeing, catalysis, and beyond. These metals' versatility is crucial to many technological advancements.