B) They have protons that are identical to the protons of all other elements
Answer:
Yes, a precipitate of PbS forms
Explanation:
The equation of the reaction is given as:
Pb(NO₃)₂ + Na₂S → PbS + 2NaNO₃
The lead sulfide forms a precipitate in the aqeous solution.
Precipitation is a form of reaction in which ions combines to form a solid precipiate. Most double displacement reactions in which ionic compounds are the reactants results in formation of a precipitate as the product.
There are rules of solubility which guides a reaction that would lead to the formation of a precipitate. The mos applicable of the rules to the reaction stated above is that "carbonates, phosphates, sulfides, oxides and hydroxides are insolube". The sulfide of lead formed in the product is therefore insoluble.
It is an endothermic reaction, the chemicals (probably water and ammonium nitrate) require more energy to react therefore it absorbs heat from it's surrounding to power the reaction and thus lowering the surrounding temperature. <span />
Atomic number = 20 -------> Ca (calcium)
Calcium has four shells (1, 2, 3, 4) and two sublevels ( s, p ).
1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
