Question

Which of the following is not a correct statement about the trends when going from left to right across the periods of the periodic table?
A. Elements become less metallic in nature.
B. The number of valence electrons increases.
C. The atoms lose their electrons more easily.
D. The oxides become more acidic.

Answer 1

We know that a period in the periodic table is a row of chemical elements and all elements belonging to a same row or period have the same number of electron shells. The physical and chemical properties of elements change accordingly following a trend of moving from left to right in a period.

Complete answer:
On moving left to right across a period, let us discuss each given trend separately as follows:
Trend-A: Elements become less metallic in nature-
On moving left to right in a period, the effective nuclear charge acting on the valence shell electrons increases and thus, the tendency to lose electrons for an atom will decrease. Therefore, electronegativity of the elements increases and the metallic character decreases on moving left to right in a period.
Trend-B: The number of valence electrons increases-
As the atomic number increases gradually, each next element in a period has one more proton as compared to its predecessor. Thus, the number of valence electrons increases on moving from left to right in a period.
Trend-C: The atoms lose their electrons more easily-
On moving left to right in a period, the atomic size of elements decreases and effective nuclear charge increases. Thus, it becomes difficult for atoms to lose electrons on moving left to right in a period. Hence, it is an incorrect statement.
Trend-D: The oxides become more acidic-
Non-metallic oxides form stable anions in aqueous solutions which means the non-metallic oxides can easily give out hydrogen ions when dissociated in water and form an acidic solution. And we know that the non-metallic character of elements increases across a period. Therefore, the oxides become more acidic when we move left to right in a period.
Hence, the correct answer to this question is option (C).

Note:
It is important to note that the metallic bond for a metallic bond is always nondirectional because electrons are not shared with a particular atom in one direction. However, the electrons are shared with many neighbouring atoms in different directions.