Question

Refer to the periodic table and indicate the physical state for each of the following elements at \(25^{\circ} \mathrm{C}\) and normal pressure: (a) \(N\) (b) \(\mathrm{Na}\) (c) \(\mathrm{Ne}\) (d) \(\mathrm{Ni}\)

Short answer

(a) Gas (b) Solid (c) Gas (d) Solid

Step-by-step solution

Identifying Physical State of Nitrogen (N)

Nitrogen, represented by the symbol \(N\), is located in Group 15 on the periodic table. At \(25^{\circ} \mathrm{C}\) and standard pressure, nitrogen exists as a diatomic molecule, \(\text{N}_2\). It is a gas under these conditions.

Identifying Physical State of Sodium (Na)

Sodium, with the symbol \(\text{Na}\), is an alkali metal found in Group 1. Metals in this group are typically solid at room temperature. Thus, sodium exists as a solid at \(25^{\circ} \mathrm{C}\).

Identifying Physical State of Neon (Ne)

Neon, represented by \(\text{Ne}\), is a noble gas located in Group 18 of the periodic table. Noble gases are known to be gaseous at room temperature. Therefore, neon is a gas at \(25^{\circ} \mathrm{C}\).

Identifying Physical State of Nickel (Ni)

Nickel, denoted by \(\text{Ni}\), is a transition metal found in Group 10 of the periodic table. Transition metals are solid under normal conditions, so nickel is solid at \(25^{\circ} \mathrm{C}\).

Key concepts

Physical States of Elements

The periodic table is a powerful tool that helps us understand the properties of elements, including their physical states at specific conditions. The physical state refers to whether an element is a solid, liquid, or gas at a given temperature and pressure. At room temperature and standard atmospheric pressure, most elements appear as either solids, gases, or in a few cases, liquids.

• Solids have a definite shape and volume, with particles packed closely together. Most metals, such as sodium (\( ext{Na}\)), are solid at room temperature.
• Gases have neither a definite shape nor volume, with particles that are widely spaced and move freely. Elements like nitrogen (\( ext{N}_2\)) and neon (\( ext{Ne}\)) are gases at room temperature.
• Liquids have a definite volume but no definite shape, adapting to the shape of their container. Mercury is a well-known metallic liquid.

It's crucial to note the exceptions, such as bromine, a non-metal that is liquid at room temperature.

Diatomic Molecules

Diatomic molecules consist of two atoms, either of the same element or different elements. Naturally occurring diatomic elements include hydrogen (\( ext{H}_2\)), nitrogen (\( ext{N}_2\)), oxygen (\( ext{O}_2\)), and the halogen gases. These elements form diatomic molecules because it's energetically favorable, enhancing their stability.

• Nitrogen (\( ext{N}_2\)) is a classic example of a diatomic molecule, making up around 78% of Earth's atmosphere. Its strong triple bond gives it remarkable stability and inertness under standard conditions.
• Oxygen is vital for respiration, and together with nitrogen, it defines the air composition in the atmosphere.

Understanding diatomic molecules helps explain many reactions in chemistry, particularly those involving gas forming processes.

Noble Gases

Noble gases are a group of elements located in Group 18 of the periodic table. They include helium (\( ext{He}\)), neon (\( ext{Ne}\)), argon (\( ext{Ar}\)), krypton (\( ext{Kr}\)), xenon (\( ext{Xe}\)), and radon (\( ext{Rn}\)). These gases are characterized by their exceptional stability and low reactivity due to their complete valence electron shells, making them chemically inert under most conditions.

Noble gases exist as monatomic gases, meaning each gas is composed of single atoms rather than molecules.

• Neon (\( ext{Ne}\)), often used in lighting, emits a distinct red-orange glow when electrified.
• Argon is commonly used in welding to provide an inert atmosphere.

Their stable nature is pivotal in many applications, from lighting to lasers and as protection for reactive processes.

Transition Metals

Transition metals occupy the central block of the periodic table, consisting of groups 3 to 12. Known for their high melting points, density, and ability to conduct electricity, these metals include familiar elements such as iron (\( ext{Fe}\)), copper (\( ext{Cu}\)), and nickel (\( ext{Ni}\)). At room temperature, transition metals are typically solid and exhibit variable oxidation states. This variability allows them to form compounds with divergent colors and magnetic properties.

• Nickel (\( ext{Ni}\)), used in alloys and plating, is known for its resistance to corrosion and high durability.
• Iron is critical in construction and manufacturing, while copper is essential for electrical wiring due to its high conductivity.

The versatility and special properties of transition metals make them invaluable in modern technology and industry.