Briefly describe the steps in the big bang that provided the protons, neutrons, and electrons necessary for nucleosynthesis – the building of complex atoms
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In the first phase of the big bang, the Universe was filled completely with gamma ray photons with very high energies.
As the highest energy gamma ray photons interacted, they produced proton-anitproton and neutron-antineutron pairs. Almost all of the pairs would annihilate and create new photons, but one in a billion pairs would leave a proton or neutron of matter behind.
As the Universe expanded and cooled, the photons dropped in energy and could no longer produce massive particles. The protons and neutrons created in the last phase remained. The photons could create electron-positron pairs. This process continued until the photon energy dropped below the threshold for creating electron-positron pairs. As with protons and neutrons, one in a billion electrons was left behind.
As the photon energy cooled, the protons, neutrons and electrons remained to begin nucleosynthesis.
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Why is iron significant to understanding how a supernova occurs?
A) Iron cannot release energy either by fission or fusion. B) Iron is the heaviest of all atomic nuclei, and thus no heavier elements can be made. C) Supernovae often leave behind neutron stars, which are made mostly of iron. D) The fusion of iron into uranium is the reaction that drives a supernova explosion.
The photoreceptors responsible for color vision are called ______________
Fill in the blank(s) with correct word
Which of the following was not a part of Dalton's atomic theory?
a. Each element is composed of atoms, which are identical for that element. b. The reactivity of elements involves changes in their electron configuration. c. Chemical combination is the bonding of a definite number of atoms of each of the combining elements. d. No atoms are gained, lost, or changed in identity during a chemical reaction.