What Is Helium Definition Atomic Number Electronic Configuration Properties and Uses
Helium is essential in chemistry and helps students understand various practical and theoretical applications related to this topic.
Learning about the properties, uses, and natural occurrence of helium prepares you for fundamental concepts in elements and gases, as well as exciting real-world examples like balloons, cryogenics, and even space research.
What is Helium in Chemistry?
A helium element refers to a noble gas with the chemical symbol He and atomic number 2. This concept appears in chapters related to atomic structure, noble gases, and periodic table trends, making it a foundational part of your chemistry syllabus.
Helium stands out due to its low density, inertness, and unique behavior at extremely low temperatures.
Molecular Formula and Composition
The molecular formula of helium is He. It consists of a single atom per molecule, as helium is a monoatomic noble gas and is categorized under Group 18 elements. Helium’s stable electron configuration (1s2) is at the heart of its chemical inactivity.
Preparation and Synthesis Methods
Helium is not synthesized in laboratory settings in large quantities due to its rarity and because it is not part of any typical chemical reaction. Instead, it is obtained through extraction from natural gas deposits, where it can be as much as 7% of the mixture.
Industrial gas separation processes—mainly fractional distillation and adsorption on cooled activated charcoal—allow the removal of other gases, leaving behind nearly pure helium. In the Earth's crust, helium is produced naturally from the alpha decay of heavy radioactive elements like uranium and thorium.
Physical Properties of Helium
Helium is a colorless, odorless, and tasteless gas at room temperature. It has the lowest boiling point among all elements at -268.9°C and remains liquid even at absolute zero under normal pressure.
Helium is lighter than air (about 1/7th its density), non-flammable, and only slightly soluble in water. It is also non-toxic, with extremely low viscosity and a unique property known as superfluidity at very low temperatures.
Chemical Properties and Reactions
Helium is an inert gas that does not form compounds easily because of its stable, fully-filled electron shell configuration. It does not react with acids, alkalis, or oxygen and is not flammable.
Under very special high-energy conditions, some exotic compounds with other noble gases or ions can be formed, but these are rare and of minimal practical significance.
Frequent Related Errors
- Confusing helium with hydrogen (hydrogen is lighter but flammable, helium is not).
- Assuming helium can react or burn like other gases (helium is chemically inert).
- Thinking helium is abundant in Earth’s air; in reality, it’s rare on Earth and mainly extracted from natural gas, not from the air directly.
Uses of Helium in Real Life
Helium is widely used in real life. Its most popular use is in filling party and weather balloons because it is lighter than air and safe (not flammable). In medicine, liquid helium is crucial for cooling MRI scanners and superconducting magnets due to its extremely low temperature.
Helium is used as a protective, inert atmosphere in arc welding, as a pressurizing agent in rocket fuel tanks, and as a safe breathing gas for deep-sea divers. Helium also finds importance in scientific research for producing super-cold conditions in physics experiments.
Relation with Other Chemistry Concepts
Helium is closely related to topics such as noble gases and atomic structure, helping students build a conceptual bridge between periodic trends and the reason behind chemical inertness. Understanding helium’s full electron shell demonstrates the basis for low reactivity seen in other Group 18 elements, too.
Step-by-Step Reaction Example
- Extraction of helium from natural gas:
Natural gas (containing helium) is cooled and pressurized to remove methane and other impurities by liquefaction. Helium remains as the last gas. - Further purification:
The remaining gases are removed by adsorption on activated charcoal at very low temperatures, isolating 99.99% pure helium.
Lab or Experimental Tips
Remember helium by its lightness and non-reactive nature. If you ever see a balloon that doesn’t burn when exposed to a flame, it’s likely filled with helium. Vedantu educators often mention helium’s use in MRI machines and cutting-edge lab experiments as a fun way to link everyday life with science.
Try This Yourself
- Write the electron configuration of helium and explain why it is inert.
- Name two differences between helium and hydrogen gases.
- List three real-life uses of helium that are important for health or science.
Final Wrap-Up
We explored helium—its structure, unique properties, real-world applications, and its inert behavior. For more in-depth explanations, live classes, and study notes on periodic trends and cool chemistry facts, check Vedantu’s chemistry modules. Understanding helium is not just key for exams, but also for discovering the wonders of science and technology.
Further Reading: Periodic Table
FAQs on Helium Element Structure Properties and Applications in Chemistry
1. What is helium in chemistry?
Helium is a chemical element with the symbol He and atomic number 2, classified as a noble gas.
- It is located in Group 18 of the periodic table.
- Helium is a monatomic, colorless, odorless, and inert gas at room temperature.
- Its electron configuration is 1s2, which gives it a completely filled valence shell.
2. What is the atomic number and atomic mass of helium?
The atomic number of helium is 2, and its standard atomic mass is approximately 4.00 u.
- Atomic number (2) means helium has 2 protons in its nucleus.
- A neutral helium atom also has 2 electrons.
- The most common isotope, He-4, contains 2 neutrons, giving a mass number of 4.
3. Why is helium chemically inert?
Helium is chemically inert because it has a completely filled valence shell with the electron configuration 1s2.
- A full outer shell makes helium highly stable.
- It has a very high ionization energy, so it does not easily lose electrons.
- It has almost zero tendency to gain or share electrons.
4. What is the electron configuration of helium?
The electron configuration of helium is 1s2.
- The number 1 refers to the first energy level.
- The letter s indicates the s orbital.
- The superscript 2 shows that two electrons occupy the 1s orbital.
5. Does helium form compounds?
Helium generally does not form stable compounds under normal conditions due to its full valence shell.
- Its complete 1s2 configuration makes it extremely unreactive.
- Under extreme laboratory conditions, unstable species such as HeH+ (helium hydride ion) can be detected.
- These species are highly reactive and not stable at standard temperature and pressure.
6. What are the physical properties of helium gas?
Helium is a colorless, odorless, tasteless, and non-flammable monatomic gas with a very low density and boiling point.
- Boiling point: about 4.22 K (−268.93 °C).
- Density at STP: approximately 0.1785 g/L.
- It is less dense than air, which makes it rise.
7. How is helium obtained industrially?
Helium is obtained industrially by fractional distillation of liquefied natural gas.
- Natural gas deposits may contain small percentages of helium.
- The gas mixture is cooled to very low temperatures.
- Components liquefy at different boiling points, allowing helium (with the lowest boiling point) to be separated.
8. What are the common uses of helium in chemistry and industry?
Helium is commonly used as a cryogenic coolant, inert shielding gas, and lifting gas.
- Liquid helium cools superconducting magnets in MRI machines.
- It provides an inert atmosphere for arc welding and sensitive chemical reactions.
- Its low density makes it suitable for balloons and airships.
9. What is the difference between helium and hydrogen gas?
Helium is a monatomic noble gas (He) that is inert and non-flammable, while hydrogen is a diatomic molecule (H2) that is highly flammable and reactive.
- Helium has atomic number 2; hydrogen has atomic number 1.
- Helium exists as single atoms; hydrogen exists as H2 molecules.
- Hydrogen reacts with oxygen: 2H2(g) + O2(g) → 2H2O(l).
10. What are the main isotopes of helium?
The two main isotopes of helium are He-3 and He-4.
- He-4 has 2 protons and 2 neutrons and is the most abundant isotope.
- He-3 has 2 protons and 1 neutron and is much rarer.
- Both isotopes have 2 electrons in a neutral atom.
