Question

1) Consider this row in the periodic table. What changes can you predict based on what information is provided by the boxes for each element?

A) The elements change from solids to gases and the valence electrons decrease in number.

B) As you move across the row, the number of electrons increases and reactivity also increases.

C) They have different atomic numbers and mass numbers; they have the same number of valence electrons.

D) Both the atomic numbers and the mass numbers increase; the least reactive element is in the last box.

USA test prep question

Answer 1

B) As you move across the row, the number of electrons increases and reactivity also increases.

Step-by-step explanation:

The periodic table is arranged in a way that if you go across a period, the number of protons, neutrons, and electrons in an element increases. In terms of reactivity, the most reactive elements are the ones which have a high electronegativity. The electronegativity of the elements increases as you travel to the right and upwards on the periodic table.