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They are both in period 1, so have their valence electrons in the first energy level. However, helium has 2 protons in the nucleus holding on to those electrons. Hydrogen has only 1 proton holding the electrons. Thus it takes more energy to remove an electron from helium than from hydrogen.
Helium fusion requires a higher temperature than hydrogen fusion because helium nuclei have a greater positive charge and repel each other more strongly, requiring more energy to overcome this repulsion and fuse together. The higher temperature provides the necessary kinetic energy for helium nuclei to collide at high enough speeds to fuse.
This one will be easy to get your head around if we back up a bit. So let's. Ready? Jump with me. Atoms are formed of a nucleus and an electron or electrons, the electron(s) forming up in orbitals around that nucleus. At elevated temperatures, the electrons start to leave. At really elevated temperatures, all the electrons go on vacation because there is soooo much energy around that the electrons cannot stay in their orbits - or anywhere else around the neighborhood. Recall that there are three basic states of matter, and you know them as solids, liquids and gases. When things are superheated, a fourth state of matter forms - plasma. Guess what the sun is. Plasma! It's a big soup of plasma! And that's 'cause it's so very, very hot. Let's jump again. One way to look at the "stuff" on the sun is as a bunch of atomic nuclei. Make sense? All the electrons are on vacation and the nuclei are floating around in the plasma soup. Heck, they are the plasma soup. It's mostly hydrogen nuclei, which are mostly single protons. There's also some helium nuclei floating around. They're mostly two protons and two neutrons. Still with us? Good. Not far to go. Jump again. Fusion is the "smooshing together" of atomic nuclei and the "gluing together" of the joined bits to keep them together. Fusion. Simple and easy. When we "smoosh" hydrogen nuclei together to make helium, we smoosh two protons together (and a couple of neutrons). Protons are positively charged. And they don't like each other! Like charges repel, remember? But at high enough energies (high enough temperatures), we can force them together and fuse them, or the stars can. Now picture two helium atoms, each with its two protons and its neutrons. Which is harder: smooshing together two hydrogen nuclei, each with a positive charge, or smooshing together two helium atoms, each with twoprotons and some neutrons? Bingo! Helium smooshing is harder, and it can only occur under conditions of higher energy - higher temperatures. The threshold temperature of hydrogen fusion (sometimes called a proton-proton reaction) is on the order of 10,000,000 K to 14,000,000 K or 10 to 14 million degrees Kelvin. Blazing hot! But the threshold temperature for helium fusion is on the order of 100,000,000 K or 100 million degrees Kelvin! Wow! Get out your Raybans and the sunblock! Need links? You got 'em.
Because the helium nuclei needs to be moving faster than hydrogen nuclei to fuse. This requires higher temperatures and densities.
Hydrogen has a small positive charge compared to helium and thus will have a weaker repulsion. A higher temperature is required to "push" the helium close enough to fuse. About 100 million degrees K compared to about 10 million degrees K for hydrogen.
The values get even higher for oxygen fusion, about 1.5 billion degrees K.
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When does helium fusion begin in a star?
Hydrogen undergoes nuclear fusion to form helium at a temperature of 107 K
What is the temperature which fusion of hydrogen into helium begins?
Fusion of hydrogen into helium typically begins at temperatures around 10 million degrees Celsius. At this temperature, hydrogen nuclei can overcome their electrostatic repulsion and come close enough for the strong nuclear force to initiate fusion reactions.
What fusion in stars occurs to create the element helium?
Hydrogen fusion occurs in stars to create helium. This process, known as nuclear fusion, involves the fusion of hydrogen nuclei to form helium nuclei, releasing large amounts of energy in the process.
What kind of change is hydrogen to helium?
nuclear fusion of hydrogen to form helium
How is helium formed from hydrogen?
Helium is formed through nuclear fusion in stars. In the core of a star, hydrogen atoms undergo fusion to form helium. This fusion process releases energy and is the source of a star's energy.
When does helium fusion begin in a star?
Hydrogen undergoes nuclear fusion to form helium at a temperature of 107 K
What type of energy is the sun's energy source?
hydrogen fusion
What is the temperature which fusion of hydrogen into helium begins?
Fusion of hydrogen into helium typically begins at temperatures around 10 million degrees Celsius. At this temperature, hydrogen nuclei can overcome their electrostatic repulsion and come close enough for the strong nuclear force to initiate fusion reactions.
What fusion in stars occurs to create the element helium?
Hydrogen fusion occurs in stars to create helium. This process, known as nuclear fusion, involves the fusion of hydrogen nuclei to form helium nuclei, releasing large amounts of energy in the process.
When does hydrogen-helium fusion and helium-carbon fusion occur in stars like our sun?
When hydrogen stocks run out
What kind of change is hydrogen to helium?
nuclear fusion of hydrogen to form helium
How is helium formed from hydrogen?
Helium is formed through nuclear fusion in stars. In the core of a star, hydrogen atoms undergo fusion to form helium. This fusion process releases energy and is the source of a star's energy.
What conditions are present in stars that cause the hydrogen to form helium?
The extreme pressure and temperature in a star's core cause hydrogen atoms to undergo nuclear fusion, combining to form helium. This fusion process releases a great amount of energy, helping to sustain the star's luminosity.
What does nuclear fusion convert hydrogen into?
Nuclear fusion converts hydrogen atoms into helium atoms. In the fusion process, hydrogen nuclei combine to form helium nuclei, releasing a large amount of energy in the form of heat and light.
What element is transformed in solar fusion?
Our sun mostly transforms hydrogen nuclei into helium by fusion, but it also fuses helium with helium, lithium with hydrogen, and beryllium with hydrogen, to make elements as heavy as boron.
Why do hydrogen and helium make up the sun?
hydrogen & helium combine with fusion of four process
The Sun's energy is generated from the fusion of?
hydrogen atoms in its core, where immense pressure and temperature cause hydrogen nuclei to fuse into helium. This fusion process releases a tremendous amount of energy in the form of light and heat, which powers the Sun and sustains life on Earth.
