Helium (from Greek: ἥλιος, romanized: helios, lit. 'sun') is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements. Helium is the second lightest and second most abundant element in the observable universe (hydrogen is the lightest and most abundant). It is present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the Sun and in Jupiter. This is due to the very high nuclear binding energy (per nucleon) of helium-4, with respect to the next three elements after helium. This helium-4 binding energy also accounts for why it is a product of both nuclear fusion and radioactive decay. Most helium in the universe is helium-4, the vast majority of which was formed during the Big Bang. Large amounts of new helium are being created by nuclear fusion of hydrogen in stars.
Helium was first detected as an unknown, yellow spectral line signature in sunlight, during a solar eclipse in 1868 by Georges Rayet, Captain C. T. Haig, Norman R. Pogson, and Lieutenant John Herschel, and was subsequently confirmed by French astronomer, Jules Janssen. Janssen is often jointly credited with detecting the element, along with Norman Lockyer. Janssen recorded the helium spectral line during the solar eclipse of 1868, while Lockyer observed it from Britain. Lockyer was the first to propose that the line was due to a new element, which he named. The formal discovery of the element was made in 1895 by two Swedish chemists, Per Teodor Cleve and Nils Abraham Langlet, who found helium emanating from the uranium ore, cleveite, which is now not regarded as a separate mineral species but as a variety of uraninite. In 1903, large reserves of helium were found in natural gas fields in parts of the United States, which is by far the largest supplier of the gas today.
Liquid helium is used in cryogenics (its largest single use, absorbing about a quarter of production), particularly in the cooling of superconducting magnets, with the main commercial application being in MRI scanners. Helium's other industrial uses—as a pressurizing and purge gas, as a protective atmosphere for arc welding, and in processes such as growing crystals to make silicon wafers—account for half of the gas produced. A well-known but minor use is as a lifting gas in balloons and airships. As with any gas whose density differs from that of air, inhaling a small volume of helium temporarily changes the timbre and quality of the human voice. In scientific research, the behavior of the two fluid phases of helium-4 (helium I and helium II) is important to researchers studying quantum mechanics (in particular the property of superfluidity) and to those looking at the phenomena, such as superconductivity, produced in matter near absolute zero.
On Earth, it is relatively rare—5.2 ppm by volume in the atmosphere. Most terrestrial helium present today is created by the natural radioactive decay of heavy radioactive elements (thorium and uranium, although there are other examples), as the alpha particles emitted by such decays consist of helium-4 nuclei. This radiogenic helium is trapped with natural gas in concentrations as great as 7% by volume, from which it is extracted commercially by a low-temperature separation process called fractional distillation. Previously, terrestrial helium—a non-renewable resource because once released into the atmosphere, it promptly escapes into space—was thought to be in increasingly short supply. However, recent studies suggest that helium produced deep in the earth by radioactive decay can collect in natural gas reserves in larger than expected quantities, in some cases, having been released by volcanic activity.
For S=0 parahelium, 1s2p-1s2s transition is allowed, but why there is no transition between 1s3p-1s3s? I think the only difference for the electron configurations is principal quantum number. The selection rules applying for 1s2p-1s2s can also be applied to 1s3p-1s3s. In other words, there is...
Homework Statement
What diameter must a helium filled balloon have to float with neutral buoyancy? The mass of the empty balloon is 2 g.
Homework Equations
FB = (density)(gravity)(Volume)
Volume of balloon = 4/3(4.13)r^2
Density = mass/Volume
The Attempt at a Solution
I know that the...
I have a small 'cryostat' which I would like to fill with liquid helium to conduct an experiment. It consists of a circular plastic kitchen measuring cup 3 inches wide at the top, 2 and 1/4 inches wide at the bottom, which is flat, and 1 and 1/2 inches deep. The plastic wall/floor is about...
I believe I know the answer to this question; I need an expert to verify it for me.
I work for a company that makes latex balloons. The people that have been here for a long time insist that if one is putting a small (5" balloon) filled with helium inside a larger (30") balloon then one must...
When using the variational method for the Helium atom, we determine that the lowest possible energy occurs when 1<z<2 where z is the atomic number. My professor elaborated that the number is within this range because there is a probability that the electron may be so close to one of the protons...
Dear Friends!
We know ionized helium has two protons in its nucleus, whereas hydrogen has one. This changes the line spectrum completely.
Why? Thank You in advance!
Homework Statement
A helium balloon is used to lift a load of101N. The weight of the envelope of the balloon is46.5N and the volume of the helium when the balloon is fully inflated is31.5m3. The temperature of the air is 0°C and the atmospheric pressure is 1.00 atm. The balloon is inflated with...
Homework Statement
Units of the problem are chosen to be such as KB = 1 and ħ = 1 so that energies are expressed in Kelvin and lengths in Å. The professor says the resulting value of ħ2 / 2 m for a 4-He atom is 6.0599278: how is that possibile?
Homework Equations
Natural units websites give...
Homework Statement
(a) Find the spatial wavefunction
(b)Show anti-symmetric wavefunctions have larger mean spacing
(c) Discuss the importance of this
(d)Determine the total orbital angular momentum
(e)Hence find the ground state term for Z=15[/B]
Homework EquationsThe Attempt at a Solution...
I have a theoretical question, I just recently learned that the spin triplet S=1 of helium in the state 1s2s is lower in energy than the 1s2 state due to the exchange interaction. I then learned that this 1s2s state has a shorter lifetime than the 1s2 state, can anyone explain why this occurs...
Homework Statement
The two-particle wavefunctions are given:
Where |V> is the spin down state and |Λ> is the spin down state
½(Ψ3p(r1)Ψ1s(r2) + Ψ1s(r1)Ψ3p(r2))(|V>|Λ> - |V>|Λ>)
½(Ψ3p(r1)Ψ1s(r2) - Ψ1s(r1)Ψ3p(r2))(|V>|Λ> + |V>|Λ>)
1/√2 (Ψ3p(r1)Ψ1s(r2) - Ψ1s(r1)Ψ3p(r2))(|Λ>|Λ>)
1/√2...
If I heat a rubber balloon filled with helium slowly and if the balloon is fully expandable and (the balloon) can be assumed to require no energy in its expansion,what type of thermodynamic process is taking place? Is it isobaric?
Since the balloon expands the pressure exerted by the gas on...
Problem statement:
A Helium filled balloon has a volume of 1 cubic meter and a mass of 0.200 kilograms. It is released and rises through the air because of its buoyancy. The buoyant force is equal to the weight of air displaced by the balloon.. This force is given by: F_b = [1.29e^(-1.21h)]g...
Homework Statement
During fusion of hydrogen to helium, 4 billion kg of matter are converted
to energy each second. What fraction of the Sun’s total mass is lost each
year to this process?
Homework Equations
None.
The Attempt at a Solution
First:
Convert how many seconds are there in a year
1...
Homework Statement
a) In the double slit interference pattern for helium atoms, the kinetic energy of a beam of atoms is 0.020 eV. What is the de Broglie wavelength of a helium atom with this kinetic energy? b) Also, estimate the de Broglie wavelength of the atoms from the fringe spacing...
Okay you're going to have to forgive me but I'm new to all of this and I'm still getting a hang of this website(as well as having little or no education/experience in much of any physics beyond high school),but I was wondering if it would be possible to make a particle accelerator that used...
If Helium is a more stable element than Hydrogen, then why wasn't just Helium formed during the process of nucleosynthesis? The matter could just have formed Helium. What was the thing that prevented it?
Suppose you have a bucket filled with superfluid Helium-4 and you spin it with a large angular velocity Ω, the bucket obviously has angular momentum.
Spinning fast enough, the fluid develops irrotational vortex lines which carry quanta of angular momentum, while leaving the curl of the ∇xv 0...
Hello everyone, I was recently creating two different types of plasma for a Science Fair, one created from ionised Helium, (although it's the party balloon stuff, and I hear there's some Oxygen in them) and the other was created from air. I was testing how the plasmas reacted to magnetic fields...
After a science fair experiment we have measured the similarities and differences of plasma created by air and helium. Our methodology is as follows.
Methodology A(air):
1. Light a match and place it on a small raised surface inside a microwave
2. Cover the match with a glass bowl/beaker...
For a science fair experiment me and my partner are working on creating plasma in a microwave.Our hypothesis is that if the manipulability of plasma is affected by the type of gas used, then plasma will react to magnetic fields differently depending on the gas that has been ionised. Because...
If a helium-filled balloon initially at room temperature is placed in a freezer, will its volume increase, decrease, or remain the same?
The Attempt at a Solution
If you decrease the T of a vessel filled with gas, its molecules will have less kinetic energy, and the pressure inside the...
In high school I took an advanced physics class, in which we learned the Bohr Derivation, after the lesson my teacher then drew a model of Helium then explained that no one however had come up with the equation to represent the spectral lines of Helium, so i had taken on this challenge to see if...
Hi all.
I am currently trying to determine the specifications of equipment I need to create a plasma. I am looking to generate a plasma in chamber of Helium at a pressure of about 0.6 Torr. My electrodes are around 17cm apart (giving me a pd of 10 Torr cm). By consulting Paschen curves, I see...
I was not sure exactly where to put this but it involves images so I thought it was no too inappropriate here.
I was reading the Feynman Lectures Vol.1 and he says that Helium, although not solid at absolute zero normally, can be so in high pressures. I then googled this for images but none...
Homework Statement
The Hamiltonian of helium can be expressed as the sum of two hydrogen Hamiltonians and that of the Coulomb interaction of two electrons.
\hat H = \hat H_1 + \hat H_2 + \hat H_{1,2}
The wave function for parahelium (spin = 0) is
\psi(1,2) = \psi_S(r_1, r_2)\dot...
Hello, I have been studying the early universe where everything was a bunch of hydrogen atoms and helium atoms. Apparently they calculated the %composition of the universe at the time. How did they do that? What sort of equations can be used to calculate these quantities?
a 9 L vessel contains 3 moles of helium and 3 moles of nitrogen at a pressure of 10 atm. Maintaining constant temperature, an additional 2 moles of helium are added. Assuming gases behave ideally, what are the partial pressures of nitrogen and helium at the end?
Initially there's: 3mol He/(3mol...
Homework Statement
Find the magnetic moment of singly ionized helium in terms of Bohr Magneton
I know the expression for the Bohr Magneton -- I am not trying to get a walk-through here as I want to do this myself, but I just want to know if I am correct in assuming that to get the problem...
Hi,
Under standard conditions, why does water have higher entropy than helium? Isn't helium a gas? I understand that water has more atoms, but it seems more ordered and is a liquid. I'm not sure how a qualitative analysis could lead to the conclusive result that water is higher in entropy...
Can someone recommend (if possible) a way to detect the amount of helium in a given enclosed space? I'm designing an experiment in which I will need to measure the amount in an otherwise vacuum.
Homework Statement
A rigid cylinder contains helium (molar mass 4kg/kmol) at a pressure of 5 bar and a temperature of 15 oC. The cylinder is now connected to a large source of helium at 10 bar and 15 oC, and the valve connecting the cylinder is closed when the cylinder pressure has risen to...
It's a theoretical study. Like the image showing, the curved piston move in container and need energy for that. In the same time, another piston move up and recover energy. The pressure inside container is always the same (need to control speed of pistons, but there is a pressure). No gravity...
I've been looking online at multiple resources and seem to be getting conflicting answers.
http://www.sciencegeek.net/tables/AtomicRadius.pdf - Where He is slightly smaller than H
http://intro.chem.okstate.edu/1314F00/Lecture/Chapter7/ATRADIID.DIR_PICT0003.gif - Where H is smaller than He...
I'm looking for a graph that shows me the root mean velocity as a function of temperature for helium gas. Does anyone know where I can find this? Thanks.
Homework Statement
Using the Bohr model, find the atomic radius for a singly ionized He+ atom in the n =
1 (ground) state and the n = 2 (first excited) state. Then find the wavelength of the
emitted photon when an electron transitions from the n = 2 to the n = 1 state.Homework Equations
a_0 =...
I understand that helium 3 has a very high probability of fusing with thermal neutrons, and the reaction produces tritium and hydrogen:
n + 3He → 3H + 1H + 0.764 MeV
however I do not understand how this reaction is detected.
Can someone please explain?
Thanks.
Homework Statement
A cylinder containing 15L of helium gas at a pressure of 165 atm is to be used to fill party balloons . Each balloons must be filled to a volume of 2L at a pressure of 1.1 atm. What is the maximum number of balloons that can be inflated? (Hint: the empty cylinder will...
Hi I have a question , now in fusion reactors like a tokamak design and also in others , if they use say the deuterium tritium mixture as fusion fuel which ends up in some released binding energy , alpha particles, a energetic neutron etc. Now the neutron and alpha particles an d all other stuff...
Hello. I am currently doing my GCSEs and I take Triple Science. My favourite science is definitely physics, and after a lesson on radioactive decay at school I came up with an idea. I remember a while ago hearing on the news that the Earth is running out of natural sources of helium.
My idea...
So I was pondering this question: On a conceptual level, how does a perfectly spherical helium balloon rise?
I understand that the density of helium gas is lower than that of our atmospheric composition of gases, but that is not giving the full perspective for me. On a molecular level, I feel...
Hi there,
Just a quick question which I'm sure I'm over complicating in my head.:confused:
I've read that Helium 4 is a Boson because it has 0 spin and that Helium 3 is a Fermion because it has 1/2 spin. Is this right? I don't see how whole atoms can be associated with fundamental particle...
Hi guys i am new here hope you are all well, had a problem with a physics question hope you can help.
Helium gas m=2.0(g) is at an initial temperature T1=100 degreees and initial pressure P1=100000 Pa, and has a volume V1. The gas undergoes isobaric (P=constant) expansion until its volume is...
Homework Statement
Consider a star that consists entirely of helium. Make an estimate of the minimum mass for which such a star can ignite helium using the following assumptions:
(i) helium ignites at a temperature of Tc = 10e8 K.
(ii) assume that the critical mass can be determined by the...
Hello, I am a physics newbie (more of a computer scientist) but I was wondering, if a quart of liquid helium 4 had all of its electrons stripped from it and was super cooled, could it still reach the super fluid state? And once reaching that state would it retain a charge attraction?
The...
At absolute zero, I understand that atoms have a minimum vibration (the atoms are not completely still). Because of this minimal vibration, He atoms can not freeze at absolute zero. But if enough pressure is applied, the liquid then becomes a solid. Does the pressure eliminate or reduce the...