Element identity
Atomic number, symbol, relative atomic mass display and periodic position are established reference data.
Atomic / electronic model
Ground-state electron configuration and atomic reference values are compiled/evaluated data; orbital graphics are teaching probability models, not photographs.
Material / molecular structure
The displayed ordinary structure is based on established material or molecular science; simplified viewers are labelled as teaching schematics where exact crystallographic coordinates are not rendered.
Temperature / phase path
Transition values are reference/evaluated values for the stated teaching path; pressure, purity and allotropy can matter.
Geography
Real pins use reviewed place/dataset context. Conceptual layers are used when country pins would imply false occurrence, unsafe inventory or an incomplete global distribution.
The lens describes evidence status, not confidence theatre. “Unknown” is kept unknown, and teaching schematics are not presented as direct measurements.
Helium (He)
Helium is element 2, a closed-shell noble gas with the lowest normal boiling point of any element. Its signature science is cryogenic: liquid helium becomes superfluid below the lambda transition, while solid helium requires pressure rather than simple cooling at 1 atm.
Helium atomic number, mass, electron configuration and key properties
Helium’s chemical symbol, or abbreviation, is He. It is a colorless gas at ordinary room temperature and pressure; its state changes at cryogenic temperatures.
Helium: quick answers
How many protons, neutrons and electrons does helium have?
Helium’s atomic number is 2, so every helium atom has 2 protons, and a neutral atom also has 2 electrons. Its most common natural isotope, helium-4, has 2 neutrons (other isotopes have different neutron counts).
What is the symbol for helium?
The chemical symbol for helium is He.
Is helium a solid, liquid or gas at room temperature?
Helium is a gas at room temperature (about 25 °C).
What family (group) is helium in?
Helium is a noble gas, in group 18, period 1 of the periodic table.
How many valence electrons does helium have?
Helium has 2 valence electrons, which fill its only shell, so it is grouped with the noble gases.
What is the electron configuration of helium?
The ground-state electron configuration of helium is 1s².
From atomic number to chemistry
Read these as a chain of causes, not as isolated facts. Each step links to the concept hub if you want the underlying idea explained.
Two protons define helium.
The first shell is completely filled.
Helium is a noble gas with a two-electron closed shell.
Two stable isotopes have very different low-temperature quantum behavior.
Helium does not freeze at 1 atm by cooling alone.
Helium in its period and family
Helium sits in Group 18 because its only electron shell is filled. Unlike the other noble gases, its filled valence shell is 1s² rather than an ns²np⁶ octet.
Helium Visual Lab
Decode helium’s tile, rotate a ⁴He teaching nucleus, inspect the spherical occupied 1s probability cloud, explore the ordinary-pressure cryogenic path through He I and superfluid He II, and connect helium to spectroscopy, natural-gas resources, MRI cooling and space science.
Every mark points to one exact feature
The numbered markers explain the same information system used throughout Element Lookup. Unknown or predicted fields remain visibly labelled rather than being replaced with guesses.
Helium in one minute
Atomic number 2 means every helium nucleus contains 2 protons.
Neutral helium has the closed-shell configuration 1s².
Helium boils at about 4.222 K at standard pressure.
Below about 2.17 K, liquid helium-4 enters the superfluid He II state.
Helium does not freeze at 1 atm merely by cooling; solid helium requires elevated pressure.
Shell rings organize electron counts. They are not electron trajectories or orbital shapes.
2 electrons
The 1s orbital is spherical and has no directional x/y/z variants. The probability cloud is an isolated-atom model; superfluidity is a collective quantum property of many helium atoms, not an orbital shape.
At ordinary conditions helium is a monatomic gas. At 1 atm it does not freeze on cooling; solid helium requires elevated pressure, so the ordinary-pressure viewer does not invent a solid crystal.. The viewer is evidence-aware: measured structures are identified as such; unknown bulk structures stay unknown.
Teaching visualization; not a literal finite sample or thermal trajectory.What this model does—and does not—show
The 1s orbital is spherical and has no directional x/y/z variants. The probability cloud is an isolated-atom model; superfluidity is a collective quantum property of many helium atoms, not an orbital shape.
Where do I meet helium?
Clickable learning cards connect the element to materials, environment, technology, biology or research - depending on what the evidence actually supports.
Cryogenics
Liquid helium cools superconducting magnets and experiments to temperatures only a few kelvin above absolute zero.
Gas -> normal liquid -> superfluid, without a 1-atm solid
Helium’s phase story is unlike an ordinary solid-liquid-gas sequence.
Monatomic helium
Above about 4.22 K at ordinary pressure, helium is a monatomic gas.
Helium, neon and argon
All are noble gases, but helium closes the first shell with only two electrons and has unique quantum-liquid behavior.
| Closed shell | 1s² |
|---|---|
| Boil | 4.222 K |
| 1 atm solid | none |
| Closed shell | 2s² 2p⁶ |
|---|---|
| Boil | 27.104 K |
| Closed shell | 3s² 3p⁶ |
|---|---|
| Context | heavier noble gas |
Helium properties: atomic, physical, thermal and chemical
Categories follow the science of this element rather than a fixed decorative template. Each row carries condition/provenance context and an evidence label; unknown values stay unknown.
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Atomic number | 2 | Source-reviewed; see Sources below | Evaluated |
| Relative atomic mass | 4.002602 | Source-reviewed; see Sources below | Evaluated |
| Ground-state electron configuration | 1s² | Source-reviewed; see Sources below | Evaluated |
| Group / period / block | Group 18 · Period 1 · s-block | Periodic-table placement | Evaluated |
| Electronegativity | Not assigned on the usual Pauling scale | Source-reviewed; see Sources below | Evaluated |
| Reference isotope | ⁴He | Source-reviewed; see Sources below | Evaluated |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| State context | Colorless monatomic gas at 20 °C | Source-reviewed; see Sources below | Evaluated |
| Density | 0.000164 g/cm³ · gas reference | Source-reviewed; see Sources below | Evaluated |
| Material / molecular structure | Monatomic helium gas · ordinary-state model | At ordinary conditions helium is a monatomic gas. At 1 atm it does not freeze on cooling; solid helium requires elevated pressure, so the ordinary-pressure viewer does not invent a solid crystal. | Measured |
| Classification | Noble gas | Periodic-table / chemistry classification | Evaluated |
| Structure-model scope | At ordinary conditions helium is a monatomic gas. At 1 atm it does not freeze on cooling; solid helium requires elevated pressure, so the ordinary-pressure viewer does not invent a solid crystal. | Teaching visualization; exact crystallographic coordinates are not implied unless stated. | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Melting / transition reference | No freezing at 1 atm · solid requires pressure | Source-reviewed; see Sources below | Evaluated |
| Boiling / gas reference | 4.222 K | Source-reviewed; see Sources below | Evaluated |
| Phase-path context | In the ordinary-pressure cryogenic teaching path, helium-4 is gaseous above about 4.222 K, liquid He I below the boiling point, and becomes superfluid He II below about 2.17 K. It does not form an ordinary solid at 1 atm; solid helium requires elevated pressure. | Shared phase registry drives the slider, regions and markers. | Evaluated |
| Condition warning | Temperature and pressure define phase behavior; purity/allotropy may matter. | Teaching condition statement | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Common oxidation states | 0 in ordinary chemistry | Source-reviewed; see Sources below | Evaluated |
| Ion / common ion context | No common stable ion | Source-reviewed; see Sources below | Evaluated |
| Periodic chemistry context | Helium sits in Group 18 because its only electron shell is filled. Unlike the other noble gases, its filled valence shell is 1s² rather than an ns²np⁶ octet. | Element-specific interpretation | Reviewed |
| Chemistry caution | Elemental form, ions and compounds are distinct chemical objects. | Interpretive teaching rule | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| ⁴He | Stable · overwhelmingly dominant natural helium | Teaching nucleus contains 2 protons and 2 neutrons; the ⁴He nucleus is also an alpha particle. | Evaluated |
| ³He | Stable · trace natural isotope | Important in low-temperature physics, neutron detection and specialized research. | Evaluated |
| Helium isotope mixture | Two stable isotopes | The abundance of ³He is tiny compared with ⁴He, but its quantum properties are profoundly different. | Evaluated |
| Teaching nucleus | ⁴He · 2 protons + 2 neutrons | Reference isotope used in the nucleus model | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Page evidence note | Atomic and boiling-point values are measured/evaluated. The He I/He II transition is a measured condensed-matter phenomenon. The page explicitly preserves the fact that helium does not have a normal 1-atm freezing point. | Evidence summary for this guide | Reviewed |
| Structure evidence | At ordinary conditions helium is a monatomic gas. At 1 atm it does not freeze on cooling; solid helium requires elevated pressure, so the ordinary-pressure viewer does not invent a solid crystal. | Measured structure, labelled schematic, prediction or explicit unknown as applicable. | Reviewed |
| Map evidence rule | Real pins are reviewed examples; conceptual layers are used when pins would mislead. | Geography Explorer 2.0 | Reviewed |
| Source set | 3 primary/reference links listed below | Open the Sources section for the actual references. | Reviewed |
Is Helium a solid, liquid or gas? State at temperature
In the ordinary-pressure cryogenic teaching path, helium-4 is gaseous above about 4.222 K, liquid He I below the boiling point, and becomes superfluid He II below about 2.17 K. It does not form an ordinary solid at 1 atm; solid helium requires elevated pressure.
Where on Earth is Helium found or produced?
Who discovered Helium, and when?
During a solar eclipse, spectroscopy revealed an unknown yellow line associated with the Sun; Norman Lockyer proposed a new solar element and named it helium.
William Ramsay isolated terrestrial helium from a uranium-bearing mineral, confirming helium on Earth.
Heike Kamerlingh Onnes liquefied helium, opening the door to ultralow-temperature physics.
The superfluid behavior of helium II became a landmark example of macroscopic quantum physics.
From helium-bearing gas to cryogenic use: a high-level path
Commercial helium is commonly recovered from natural-gas streams that contain unusually high helium concentrations.
Gas processing separates major components before cryogenic purification concentrates helium; detailed plant-operation guidance is outside this page.
Purified helium is distributed for cryogenics, leak detection, controlled atmospheres and specialized industrial/scientific uses.
In high-value systems, recovery and reliquefaction can reduce losses of this finite terrestrial resource.
What is helium used for?
Cryogenic cooling
Helium enables temperatures low enough for superconducting magnets and condensed-matter experiments.
Leak detection
Helium tracer methods can reveal very small leaks in vacuum and pressure systems.
Shielding / inert atmospheres
Helium can provide inert gas environments for selected manufacturing processes.
Aerospace
Low density and inertness support pressurization and purge roles in specialized aerospace systems.
Helium isotopes and natural abundance
⁴He
Stable · overwhelmingly dominant natural heliumTeaching nucleus contains 2 protons and 2 neutrons; the ⁴He nucleus is also an alpha particle.
³He
Stable · trace natural isotopeImportant in low-temperature physics, neutron detection and specialized research.
Helium isotope mixture
Two stable isotopesThe abundance of ³He is tiny compared with ⁴He, but its quantum properties are profoundly different.
Five-question Helium check
What is helium’s atomic number?
What is helium’s ground-state electron configuration?
What happens to helium-4 below about 2.17 K?
Can helium freeze at 1 atm by cooling alone?
What is ordinary gaseous helium made of?
Helium questions students commonly ask
Each answer starts with the direct fact, then explains the chemistry, evidence or material context so the result is understandable rather than merely memorized.
What is helium’s atomic number?
Short answer: 2.
Atomic number is defined by proton count, so 2 protons are what make an atom helium. A neutral helium atom also has 2 electrons, while isotopes can have different neutron counts without changing the element.
Key point: Atomic number = proton count.
What is helium’s symbol?
Short answer: He.
The symbol He is the standardized chemical abbreviation for element 2. In a chemical formula, He identifies helium atoms; a compound containing He is not automatically the same material as elemental helium.
Key point: He always identifies element 2.
Why is helium a noble gas?
Short answer: Helium is placed in Group 18 because its 1s shell is completely filled (1s²) and it is extraordinarily unreactive under ordinary conditions.
Helium is a useful exception to the classroom “octet” shortcut: its only occupied shell is the first shell, which is complete with two electrons. That closed 1s² configuration is energetically stable and helium has a very high ionization energy. Helium is chemically grouped with the noble gases even though, by electron-configuration block, it is an s-block element.
Key point: Noble-gas behavior comes from a filled valence shell; helium has a filled duet, not an octet.
What is helium used for?
Short answer: Major uses include cryogenic cooling, leak detection, inert atmospheres and specialized aerospace/scientific applications.
Cryogenic cooling: Helium enables temperatures low enough for superconducting magnets and condensed-matter experiments. Leak detection: Helium tracer methods can reveal very small leaks in vacuum and pressure systems. Helium’s famous balloons are only one part of the story. The deeper physics lies near 4 K, where quantum behavior becomes macroscopic in liquid helium.
Key point: Always distinguish the pure element from the compound, alloy, isotope or device material that actually performs the application.
Can helium freeze at 1 atmosphere?
Short answer: No. Helium remains liquid down to very low temperature at 1 atm; forming solid helium requires added pressure.
In the ordinary-pressure cryogenic teaching path, helium-4 is gaseous above about 4.222 K, liquid He I below the boiling point, and becomes superfluid He II below about 2.17 K. It does not form an ordinary solid at 1 atm; solid helium requires elevated pressure.
Key point: Phase statements need temperature, pressure and evidence context.
What is superfluid helium?
Short answer: Below the lambda transition near 2.17 K, liquid helium-4 enters He II, a quantum fluid with extraordinary flow and heat-transport behavior.
Helium is element 2, a closed-shell noble gas with the lowest normal boiling point of any element. Its signature science is cryogenic: liquid helium becomes superfluid below the lambda transition, while solid helium requires pressure rather than simple cooling at 1 atm. Below about 2.17 K, liquid helium-4 enters the superfluid He II state.
Key point: The mechanism matters: connect the observed behavior to electron structure, bonding, phase or the specific material form rather than memorizing the result alone.
Is helium flammable?
Short answer: No. Helium is a nonflammable noble gas. Its main hazards are physical, such as displacement of oxygen in confined spaces and extreme cold when liquefied.
Helium sits in Group 18 because its only electron shell is filled. Unlike the other noble gases, its filled valence shell is 1s² rather than an ns²np⁶ octet. Helium is element 2, a closed-shell noble gas with the lowest normal boiling point of any element. Its signature science is cryogenic: liquid helium becomes superfluid below the lambda transition, while solid helium requires pressure rather than simple cooling at 1 atm.
Key point: The mechanism matters: connect the observed behavior to electron structure, bonding, phase or the specific material form rather than memorizing the result alone.
Scientific sources for Helium
- Royal Society of Chemistry - Helium
- NIST - Cryogenic helium references
- USGS - Mineral Commodity Summaries 2026
- RSC — Helium
Questions to ask next about Helium
A good element lesson should lead to the next useful question, not end after a list of facts.
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