Question

Match each of the elements on the right with its description on the left: (a) A dark-red liquid (b) A colorless gas that burns in oxygen gas (c) A metal that reacts violently with water (d) A shiny metal that is used in jewelry (e) An inert gas Calcium (Ca) Gold \((\mathrm{Au})\) Hydrogen \(\left(\mathrm{H}_{2}\right)\) Argon (Ar) Bromine \(\left(\mathrm{Br}_{2}\right)\)

Short answer

(a) Bromine, (b) Hydrogen, (c) Calcium, (d) Gold, (e) Argon.

Step-by-step solution

Identify the dark-red liquid

Bromine \(Br_2\) is the only nonmetallic element that is a liquid at room temperature and has a distinctive dark-red color. Therefore, match (a) with Bromine.

Identify the colorless gas that burns

Hydrogen \(H_2\) is a colorless, odorless gas that is highly flammable and burns in oxygen to form water. Therefore, match (b) with Hydrogen.

Identify the metal reacting violently with water

Calcium (Ca) is an alkaline earth metal that reacts with water, though not as violently as alkali metals. In this context, Calcium is the appropriate option. Match (c) with Calcium.

Identify the shiny metal used in jewelry

Gold \(Au\) is well-known for its shiny yellow luster and is commonly used in jewelry due to its resistance to tarnish and corrosion. Match (d) with Gold.

Identify the inert gas

Argon (Ar) is a noble gas, which means it is inert and does not readily react with other elements. Match (e) with Argon.

Key concepts

Physical Properties of Elements

Understanding the physical properties of elements is essential in element identification. It helps us determine how elements differ in appearance, state of matter, and other traits. For instance, Bromine is distinctive for being a dark-red liquid at room temperature, which is unusual since most elements are solids or gases under these conditions.
On the other hand, Gold is known for its shiny, yellow appearance and excellent malleability, characteristics that make it highly desirable in jewelry making.

State of Matter: Elements may be solid, liquid, or gas at room temperature. This can be a key property for identification.

Color and Luster: The visual appearance of an element, such as color or shininess, can help distinguish between metals, nonmetals, and metalloids.

Density and Malleability: Metals like Gold have high density and are malleable, allowing them to be shaped into jewelry.

Knowing these properties helps in classifying and using elements effectively.

Element Reactivity

Element reactivity involves how readily an element undergoes a chemical reaction. Different elements react at varying rates and with different compounds. Calcium is an example of an element that reacts with water, producing calcium hydroxide and hydrogen gas.
Bromine, another reactive nonmetal, can engage vigorously in reactions, forming compounds with a wide range of elements.

Reactivity with Water: Elements like Calcium that react with water exhibit typical chemical changes like gas evolution and formation of hydroxides.

Flammability: Hydrogen is flammable and reacts explosively with oxygen to produce water, illustrating its high reactivity.

Noble Metals: Elements such as Gold have low reactivity and resist oxidation in air, maintaining their luster over time.

Exploring these reactivities allows for safer handling and creative utilization of elements in different sectors.

Chemistry Education

Chemistry education involves learning about elements, compounds, and their interactions. Engaging with exercises like element matching improves understanding of fundamental concepts, solidifying the students' grasp on topics. It's essential to explore both theoretical aspects and practical applications.
Practical sessions, such as observing reactions or conducting experiments, are crucial.

Interactive Learning: Games and quizzes that involve element identification can make learning engaging and memorable.

Theoretical Knowledge: Understanding chemical symbols and periodic trends forms the basis of chemical education.

Practical Applications: Laboratory experiments provide hands-on experience with elements and compounds.

Combining various learning forms supports a comprehensive grasp of chemistry, preparing students for advanced studies.

Noble Gases

Noble gases are unique because of their lack of chemical reactivity due to having complete valence electron shells. Argon is a well-known noble gas, used in various applications due to its inertness.
Since noble gases do not easily form compounds, they are used where non-reactivity is essential.

Inertness: Noble gases, such as Argon, do not react under standard conditions, making them useful in environments like light bulbs to prevent filament burnout.

Applications: The non-reactivity and colorless nature of noble gases make them ideal for use in neon signs and to provide a stable atmosphere in welding processes.

Periodic Trend: As you move down the group of noble gases in the periodic table, the atomic size increases, but the reactivity remains low.

Understanding noble gases is crucial because their unique properties offer specific advantages in scientific and industrial applications.