helium
/'hi:ljəm/
Definition
- Noun:
- A chemical element: Helium is a very light, colorless, odorless, and tasteless gas that is chemically inert, meaning it does not easily react with other elements. It is the second lightest and second most abundant element in the observable universe.
- A specific substance: In its natural state on Earth, helium is a monatomic gas (its atoms are not bonded into molecules) and is one of the noble gases. It is extracted from natural gas deposits.
Usage
- Helium is primarily used for its unique physical properties, such as low density and low boiling point.
- It is commonly used to fill balloons and airships because it is lighter than air and non-flammable.
- In science and industry, it is used as a coolant (e.g., in MRI scanners and for superconducting magnets), as a protective gas in welding, and in leak detection.
Examples
- Noun:
- The party balloons were filled with helium, so they floated to the ceiling.
- Liquid helium is essential for cooling the magnets in many scientific experiments.
- Helium is often mixed with oxygen for deep-sea diving to prevent nitrogen narcosis.
Advanced Usage
- "Helium voice": The high-pitched, squeaky sound a person's voice makes after inhaling helium gas from a balloon, caused by the speed of sound being faster in helium than in air.
- The children laughed at the comedian's helium voice.
Variants and Related Words
- Helium-3 (³He) (n): A rare, stable isotope of helium with two protons and one neutron. It has potential applications in nuclear fusion research and cryogenics.
- Helium-4 (⁴He) (n): The most common isotope of helium, with two protons and two neutrons.
- Liquid helium (n): Helium cooled to extremely low temperatures (below -269°C or 4.2 K), where it becomes a liquid with remarkable properties like superfluidity.
Synonyms
- Element 2: Referring to its atomic number on the periodic table.
- Inert gas / Noble gas: A category of gases to which helium belongs due to its lack of chemical reactivity.
Related Phrases
- Helium star (n): In astronomy, a type of star that has a surface dominated by helium, often as a late stage in stellar evolution.
- Helium flash (n): A brief, explosive ignition of helium fusion in the core of a low-mass star.
Noun
-
a very light colorless element that is one of the six inert gasses; the most difficult gas to liquefy; occurs in economically extractable amounts in certain natural gases (as those found in Texas and Kansas)
Khám phá thêm
Các từ liên quan
Từ đồng nghĩa
Từ chứa "helium"
Từ có nhắc đến "helium"
