Advertisements
Advertisements
प्रश्न
How does Chemical reactivity of elements change on going from left to right in a period of the periodic table?
Give example in support of your answer.
उत्तर
On moving from left to right in a period of the periodic table, the chemical reactivity of the elements first decreases and then increases.
For example, in the third period elements comprising of Na, Mg, Al, Si, P, S and Cl, sodium (Na) is very reactive as it has one valence electron, and can therefore, lose its electron easily. The chemical reactivity gradually decreases as we go to aluminium (Al) and silicon (Si). This is because the number of valence electrons increases, making it difficult to lose electrons. Moving further right in the period towards non-metals, the chemical reactivity again gradually increases. Phosphorus (P) has 5 valence electrons and needs 3 electrons to complete its octet. Sulphur (S) has 6 valence electrons and needs 2 more electrons to complete its octet. Chlorine (Cl) has 7 valence electrons and needs only one more electron to complete its octet. As chlorine can easily accept an electron as compared to phosphorus and sulphur, the chemical reactivity increases from phosphorus to chlorine.
APPEARS IN
संबंधित प्रश्न
The position of eight elements in the Modern Periodic Table is given below where atomic numbers of elements are given in the parenthesis.
| Period No. | ||
| 2 | Li(3) | Be(4) |
| 3 | Na(11) | Mg(12) |
| 4 | K(19) | Ca(20) |
| 5 | Rb(37) | Sr(38) |
(i) Write the electronic configuration of Ca.
(ii) Predict the number of valence electrons in Rb.
(iii) What is the number of shells in Sr?
(iv) Predict whether K is a metal or a non – metal.
(v) Which one of these elements has the largest atom in size?
(vi) Arrange Be, Ca, Mg and Rb in the increasing order of the size of their respective atoms.
Classify the following elements into metals, non-metals and metalliods
As, C, Hg, Mg, S, Si
In each of the following pair, choose the atom having the bigger size:
Na (At. No. 11) or K (At. No. 19)
Correct the statements.
Elements in the same periods have equal valency.
What do you understand by periodicity?
Chorine in the periodic table is surrounded by the elements with atomic number 9, 16, 18 and 35.
Which is more electronegative than chlorine?
K, Pb, Ca, Zn (In the increasing order of the reactivity)
State whether the following statement is true or false
On moving horizontally across a period, number of valence electrons increases from one to eight.
Parts (i) to (v) refer to changes in the properties of elements on moving from left to right across a period of the periodic table. For each property, choose the letter corresponding to the correct answer from the choices (a), (b), (c) and (d).
(i) The non metallic character of the elements:
(a) Decreases
(b) Increases
(c) Remains the same
(d) Depends on the period
(ii) The electro negativity
(a) Depends on the number of valence electrons
(b) Remains the same
(c) Decreases
(d) Increases
(iii) The ionization potential
(a) Goes up and down
(b) Decreases
(c) Increases
(d) Remains the same
(iv) The atomic size
(a) Decreases
(b) Increases
(c) Remains the same
(d) Sometimes increases and sometimes decreases
(v) The electron affinity of the elements in groups 1 to 7:
(a) Goes up and down
(b) Decreases and then increases
(c) Increases
(d) decreases
Electron Affinity is maximum in ______.
