Question

In third row of periodic table from Na to Cl
A.Electronegativity increases
B.Electronegativity decreases
C.Ionization energy decreases
D.Atomic volume increases

Answer 1

Hint: We could define electronegativity as a parameter which is used to measure the ability of an atom to attract the electron bonding pair. When the electronegativity of an atom is more, its tendency to attract shared electrons would be greater. A method to determine electronegativity in Pauling scale. According to the Pauling scale, the electronegativity of fluorine is more and the electronegativity of cesium is less.

Complete answer:
We know that period is the term given to the row of chemical elements and column is the term given to the column of chemical elements. We have defined electronegativity as a quantity which measures the ability of an atom to attract the electrons.
We have to know that the electronegativity of atoms increases when we move from left to right across a period in the periodic table. The reason is because when we move from left to right across a period, there would be faster increase in nuclear charge when compared to shielding of electrons. Thus, the attraction that the atoms contain for the outermost electrons increases.
We know that the elements in the third row of the periodic table are sodium, magnesium, aluminum, silicon, phosphorus, sulfur, and chlorine. We have to know that the electronegativity of sodium would be lowest and chlorine would be highest. When we move from left to right across periods, the electronegativity could increase.
In the third row of the periodic table from sodium to chlorine, there would be an increase in electronegativity.

So, we can conclude that option (A) is correct.

Note:
We have to remember that on moving down the group the value of electronegativity decreases. In general ways, we can notice that the electronegative value of metals is lower when compared to electronegative value of non-metals. We can remember that fluorine is the most electronegative element in the periodic table and cesium is the less electronegative element. In better words, cesium is electropositive.