How does the formation of covalent bonds relate to the octet rule? (from discovery education)

Covalent bonding occurs when atoms share valence electrons to form a chemical bond. Atoms of nonmetals form covalent bonds by sharing electrons in order to achieve an octet of valence electrons, like the noble gases, except for helium, which only has two valence electrons. The octet refers to the highest energy s and p sublevels, the valence shell, which in noble gases, except for helium, are filled with eight electrons, two in the s sublevel and six in the p sublevel.

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml