It took 380,000 years for electrons to be trapped in orbits around nuclei, forming the first atoms.
These were mainly helium and hydrogen, which are still by far the most abundant elements in the universe. Present observations suggest that the first stars formed from clouds of gas around 150–200 million years after the Big Bang. Heavier atoms such as carbon, oxygen and iron, have since been continuously produced in the hearts of stars and catapulted throughout the universe in spectacular stellar explosions called supernovae.
Answer:
D. Two reactants combine to form one product
Explanation:
The definition of synthesis in chemistry is "the production of chemical compounds by reaction from simpler materials."
A is decomposition, B is DOUBLE replacement, and C is SINGLE replacement.
Answer:
Explanation:
Alkaline earth metals are in group 2. The number of valence electrons of elements in group 2 is 2.
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PLEASE HELP I HAVE TO DO THIS BENCHAMRK QUESTION!!!
The chart shows parts of a plant and an animal, at different levels of organization. Consider the plant images. If we are referring to levels of organization in a plant which picture can BEST be used to fill in box Y?
first picture (A
