Helium

Helium is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table. Its boiling and melting points are the lowest among the elements and it exists only as a gas except in extreme conditions.

Properties of Helium:

• Atomic number: 2
• Atomic mass: 4.0026 g/mol
• Boiling point: -268.9°C
• Melting point: -272.2°C
• Density: 0.1786 g/L
• It is the second lightest element and is the second most abundant element in the observable universe, being present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined.

Uses of Helium:

Helium has several important applications, including:

• Used in cryogenics, as a cooling medium for superconducting magnets in MRI machines and other medical devices.
• Used as a protective gas for many industrial processes, such as arc welding and growing silicon wafers.
• Used as a lifting gas in balloons and airships due to its low density and non-flammability.
• Used in diving to dilute the high-pressure oxygen, providing a safer breathing medium at depth.

Study Guide:

To study helium effectively, it's important to understand its properties, uses, and its place in the periodic table. Here are some key points to focus on for your study:

1. Learn the atomic number and atomic mass of helium.
2. Understand the physical properties of helium, such as its boiling and melting points, and density.
3. Explore the abundance of helium in the universe and its unique characteristics as a noble gas.
4. Examine the various practical applications of helium in different industries and scientific fields.
5. Consider the environmental and economic significance of helium, especially in the context of its scarcity on Earth.

By grasping these concepts, you will develop a comprehensive understanding of helium and its importance in various scientific and industrial contexts.