How many valence electrons are there in each of the following elements AND COMPOUNDS (add up the valence electrons for each atom). Show your addition for the compounds:
18) Ca
19) P
20) Se
21) NH3
22) NF3
23) Al2(CO3)3

Explanation:

Ca = +2

P = -3

Se = 0

NH3=

N = -3 , H = +1 , H3 = 3 x +1 = +3

-3 + (+3) = 0

NH3 = 0

NF3

N = -3, F = -1 , F3 = 3 x (-1) = -3

-3 + -3 = -6

Al2(CO3)3

CO3

C= +4, O = -2, O3 = 3 x (-2) = -6

CO3 = +4 + (-6) = +4 - 6 = -2

(CO3)3 = 3 x (-2) = -6

Al = +3, Al2 = 2 x (+3) = +6

Al2(CO3)3 = +6 + (-6)= 0

water and alcohols have similar properties because water molecules contain hydroxyl groups that can form hydrogen bonds with other water molecules and with alcohol molecules, and likewise alcohol molecules can form hydrogen bonds with other alcohol molecules as well as with water.

the formula for the conversion of temperature from degree celsius to kelvin is:

the sample of water at is converted to kelvin temperature by using the above formula as:

on comparing the two samples of water at or we can say that at and at respectively. the difference between the temperatures of two samples of water is:

hence, one can say that the sample of water at is greater than the sample of water at by .