What are the main functions of the human skeletal system? A To support the body, protect the organs, produce blood cells, and store calcium.
To regulate the composition of body fluids by removing metabolic wastes and retaining a balance of water, salt, and other
nutrients
OcTo regulate and maintain bodily functions by producing hormones and releasing them into the bloodstream.
D. To enable the diffusion of oxygen into the bloodstream and the removal of carbon dioxide from the bloodstream.

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is and electronic configuration of phosphorous is .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.  

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.

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