Answer:
Explanation:
Valance electrons are loosely held electrons of an atom. They are involve in chemical reaction. Consider the example of metals such as group two metals. All these have two valance electrons. They needed six electrons to complete the octet or loses two valance electrons to get complete octet. Thus its easier to remove two electrons than getting six electrons. These metals remove two electrons and form cations.
Now consider the example of nonmetals such group sixteen. They needed two electrons to get complete octet or remove six electrons to get complete octet. Thus its easier for them to get two electrons and they form anion. When group two metals cation and group sixteen anions combine they form compound and chemical reaction occur.
Group two metals also combine with halogens. Two halogens atoms combine with one alkaline earth metal atom to cancel the charge and make compound neutral.
They react with oxygen and form oxide.
2Ba + O₂ → 2BaO
2Mg + O₂ → 2MgO
2Ca + O₂ → 2CaO
Oxygen carry -2 charge while Ca, Mg and Ba +2 and make the compound neutral because charges are equal in magnitude.
With sulfur,
Mg + S → MgS
Ca + S → CaS
Ba + S → BaS
Sulfer carry -2 charge while Ca, Mg and Ba +2 and make the compound neutral because charges are equal in magnitude.
The chemicals combination of the atoms is called a compound. The bond is formed between the atoms of each of the reacting elements thereby forming a new substance altogether. The compound will often exhibit different characteristics from the originating elements.
C. Ninhydrin is used to detect prints on a non-porous surface
<span>Assume you have 1.00 L (1000 mL) of solution.
d = m / V
m = d x V = 1.23 g/mL x 1000 mL = 1230 g of solution
0.387 mol/L x 1 L = 0.387 mol HCl
0.387 mol HCl x (36.5 g / 1 mol) = 14.1 g HCl
mass of water = 1230 g solution - 14.1 g HCl = 1216 g H2O = 1.216 kg H2O
molality = mol HCl / kg water = 0.387 mol / 1.216 kg = 0.318 mol/kg (or 0.318 molal)</span>
