YOU ARE LEARNING:
Creation of Elements
Creation of Elements
All the elements in the Universe are formed inside of stars and supernovae, thanks to nuclear fusion.
All stars are formed from a nebula, which is a cloud of dust and gas. What type of gas makes up most of the nebula?
All this hydrogen was first created at the very beginning of the Universe, during the _____ _______.
What elements are created in main sequence stars?
So protostars are predominantly made of hydrogen, some helium and dust.
When gravity causes the pressure and temperature to rise enough, nuclear fusion of hydrogen begins.
What element is formed in the newly formed main sequence star when two nuclei of hydrogen, , fuse?
All stars begin as predominantly hydrogen
As soon as nuclear fusion occurs in their core, helium is created. This process continues in main sequence stars until all the hydrogen runs out.
When a main sequence star the size of our Sun runs out of hydrogen, it turns into a _____ _______.
When the main sequence star runs out of hydrogen, it starts to fuse helium instead.
Helium fusion releases more energy and the outwards pressure that the fusion causes increases. This makes the main sequence star glow red and expand into a red giant.
What elements are created in red giants?
Nuclei of helium, , have two protons and two neutrons. What do you think is created when three helium nuclei are fused together?
What element is created when you add another helium nucleus, , to a carbon atom, ?
So red giants produce carbon and oxygen.
Carbon is created from three helium nuclei that fuse together. When an extra helium nucleus fuses with the carbon nucleus, it produces oxygen.
Red giants don't have enough energy to fuse carbon and oxygen together.
So when the energy runs out, they shed their layers forming a planetary nebula.
Pick all the options that you think this planetary nebula after a red giant is made up of.
You can select multiple answers
When a red giant has shed its layers, only its core is left behind
That core is called a white dwarf.
The stars that can produce heavier elements, like iron are super massive. What do we call the red giants that these stars turn into?
What elements are created in red supergiants?
Red supergiants are formed when super massive main sequence stars begin to fuse helium
Because they are so massive, these stars can raise their temperatures higher than the smaller stars like our Sun. This means they can continue to fuel nuclear fusion for longer.
Heavy elements can only be created by these larger stars. Which four of these elements can only be created in red supergiants and not in red giants?
You can select multiple answers
So bigger stars can produce and burn heavier elements, like nitrogen and silicon.
They can form elements ranging from oxygen, , to iron, . Iron is the most stable element, so once a star starts to form iron, nuclear fusion stops.
Once the fusion in a red supergiant stops, the forces in the star become imbalanced and the unstable star explodes in a ________________.
Right before exploding, the star releases very large amounts of energy and neutrons
This produces elements that are even heavier than iron, like uranium and gold. The supernova explosion launches all of these elements across the universe.
Summary
The Big Bang...
produced hydrogen and some helium.
Main sequence stars...
fuse hydrogen into helium.
Red giants...
fuse helium into carbon and oxygen.
Red supergiants...
are so massive that they have enough energy to also fuse carbon, oxygen and other elements into even heavier elements like nitrogen, magnesium, silicon, sulfur and finally iron.
In a supernova...
the red supergiant explodes which produces metals as heavy as gold and uranium and launches them across the universe.