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) helium (b) manganese (c) iodine (d) mercury

Short answer

(a) gas, (b) solid, (c) solid, (d) liquid.

Step-by-step solution

Identify Helium's Physical State

Helium ( 0_{ ext{2}}^{ ext{2}} ext{He}) is located in Group 18 of the periodic table, in the noble gases group. It is a colorless, odorless gas at room temperature and normal pressure.

Identify Manganese's Physical State

Manganese (9^{ ext{55}} ext{Mn}) is found in Group 7 of the periodic table and is classified as a transition metal. At room temperature ( 25^ 03 ext{C}), it is in a solid state.

Identify Iodine's Physical State

Iodine (
27^{ ext{53}} ext{I}) is located in Group 17, known as the halogens. At room temperature, iodine is found as a dark, lustrous solid, though it can sublimate into a purple gas.

Identify Mercury's Physical State

Mercury (0^{ ext{200.59}} ext{Hg}) is categorized as a transition metal and is known for being one of the few metals that is a liquid at room temperature and normal pressure.

Key concepts

Physical States of Elements

Understanding the physical states of elements is crucial for comprehending their properties and uses. At room temperature, which is approximately going to help us determine whether elements are in a solid, liquid, or gaseous state. For example, helium is a gas, manganese is a solid, and mercury is a liquid at room temperature. The physical state affects how these elements interact in chemical processes and their application in the real world.

Noble Gases

Noble gases belong to Group 18 of the periodic table. These gases, including helium, neon, argon, krypton, xenon, and radon, are characterized by their full valence electron shell. - **Chemically Inert**: Noble gases are unreactive under standard conditions. This makes them extremely stable.
- **Physical State**: At room temperature, they exist as colorless and odorless gases.
- **Applications**: Due to their stability, noble gases are often used in lighting, welding, and as inert environments for chemical reactions.
Helium, for instance, is used in balloons and as a cooling agent in MRI machines due to its low density and non-flammable nature. Understanding the unique characteristics of noble gases highlights their role in both natural processes and technological applications.

Transition Metals

Transition metals are located in the central block of the periodic table, typically between Group 3 and Group 12. They include elements like manganese and mercury. - **Distinct Properties**: They can exhibit a variety of oxidation states, and they often form colored compounds.
- **Physical States**: Most transition metals are solids at room temperature. An exception is mercury, which is liquid at this temperature.
- **Uses and Occurrence**: These metals are crucial in construction, manufacturing, and even biological systems. For example, manganese is integral in steel production, while mercury is used in thermometers and dental amalgams.
The versatility and wide application of transition metals are what make them vital to both industrial processes and everyday items.

Halogens

Halogens are part of Group 17 in the periodic table. This group includes fluorine, chlorine, bromine, iodine, and astatine. - **Reactive Nature**: Halogens are highly reactive, especially with alkali and alkaline earth metals, to form salts.
- **Physical States**: They can be found in all three states of matter at room temperature: chlorine is a gas, bromine is a liquid, and iodine is a solid.
- **Industrial and Biological Significance**: Iodine, for example, is crucial in human health where it is a vital component of thyroid hormone, and in disinfectants due to its antimicrobial properties.
By understanding halogens, we gain insight into their crucial roles in environmental chemistry, medicine, and industrial applications, showcasing the diversity of this unique group of elements.