The positions of elements X, Y, Z in the Periodic Table are given below. Group 16 Group 17 - X - - Y Z What will be the valency of elements X and Y?

The valency of an element X is - 1 , and Y is - 2 . The number of valence electrons in the element X is 7 and Y is 6 as they belong to groups 17 and 16 respectively. If the number of electrons is in the outermost shell are 5, 6, 7 then that element can accept 1, 2 or 3 electrons having -1, -2, -3 valency and that element will show nonmetallic character. The number of electrons that must be lost or gained by an atom to obtain a stable electron configuration.

A part of the Periodic Table is given below: From the above table, answer the following question. Which element is most metallic?

Potassium is most metallic. Metallic character increases down the group because as the number of shells increases the distance between the nucleus and outermost shell increases, thus the force of attraction between nucleus and valence electrons decreases. Conversely, the metallic character decreases across the period because the nuclear charge increases as the shells remaining the same. So, the tendency to lose electrons decreases. So, the metallic character decreases, and the nonmetallic character increases.

A part of the Periodic Table is given below: From the above table, answer the following question. Which element is most nonmetallic?

Fluorine ( F ) is the most nonmetallic element. The metallic character decreases across the period because the nuclear charge increases as the shells remaining the same. So, the tendency to lose electrons decreases. So, the metallic character decreases, and the nonmetallic character increases. Conversely, metallic character increases down the group because as the number of shells increases the distance between the nucleus and outermost shell increases, thus the force of attraction between nucleus and valence electrons decreases.

A part of the Periodic Table is given below: From the above table, answer the following question. Which element is an inert gas?

Argon is an inert gas. All the elements in group 18 are unreactive gases. They are so unreactive that they are called noble gases. Their lack of activity makes them very useful. Argon is used when aluminium is being welded to stop it from catching fire.

A part of the periodic table is given below Which element is smaller in size between O and Se?

Element oxygen (O) is smaller in size because it comes before selenium. In the group (O, Se) and down the group size of the atom increases. The atomic size of the elements increases on moving from top to bottom in a group. This is due to the presence of one extra shell of an electron at each step.

A part of the Periodic Table is given below: Which is more chemically reactive between Na and Mg?

Sodium (Na) is more chemically reactive than magnesium. Sodium has one valence electron and magnesium has two. If this valence electron is lost, then noble gas configuration is obtained. It is easy to lose one electron than two, so sodium is more reactive than magnesium.