Le diamant est un cristal constitué uniquement
d'atomes de carbone. On
considère que ces atomes sont
tous des atomes de carbone
12 (A = 12 nucléons). Il faut
en moyenne traiter 20 tonnes
de minerai pour extraire 1,0 g
de diamant, soit 5,0 carats.
Le diamant coûte très cher:
un diamant de 1,1 carat peut être vendu 15 000 €.
• Combien coûte un «atome de diamant»?
Donnée
mnucléon = 1,67 x 10-22 kg.

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.

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.