Dimitri Mendeleev was the first to put elements together on a table. He knew there were elements missing but he noticed a trend in some of the elements known at the time. Sodium, Lithium and other alkali metals all have the same properties so he put them under the same column and created other columns with similar attributes (Halogens, Noble gases, Alkaline earth metals). Over the years, new elements were discovered and put into the rough outline that Mendeleev created.
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Answer:
What happens when electrons in atoms absorb or release energy? When electrons absorb or release energy, their electrons can move to higher or lower energy levels. These electrons lose energy by emitting light when they return to lower energy levels.
Explanation:
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Answer:
Both compounds are colorless, so a mixture of them will look transparent. Both molecules are nopolar, therefore they will associate with each other through London interactions, also known as Van del Waals forces or as transient dipole-transient dipole interactions.
Explanation:
The energy of the carbide released is 7262.5MJ.
<h3>What is the energy?</h3>
We know that the reaction between calcium oxide and carbon occurs in accordance with the reaction; 
. The reaction is seen to produce 464.8kJ of energy per mole of carbide produced.
Number of moles of 
produced = 1000 * 10^3 g/64 g/mol
= 15625 moles of calcium carbide
If 1 mole of transfers 464.8 * 10^3 J
15625 moles of calcium carbide transfers 15625 moles * 464.8 * 10^3 J/ 1 mol
= 7262.5MJ
Learn more about reaction enthalpy:brainly.com/question/1657608
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