Advertisements
Advertisements
Question
The elements Li, Na and K, each having one valence electron, are in period 2, 3 and 4 respectively of modern periodic table.
(i) In which group of the periodic table should they be ?
(ii) Which one of them is least reactive ?
(iii) Which one of them has the largest atomic radius ? Give reason in justify your answer in each case.
Solution
Electronic configuration of Li, Na and K can be written as:
Li → 2, 1
Na → 2, 8,1
K → 2, 8, 8, 1
(a) As all of them have only on electron in their valence shell they belong to Group 1.
(b) Li is the least reactive among them due to its smallest size as it has only 2 shells.
(c) K has the largest atomic radius among the three because it has maximum number of shells.
Higher the number of shells, larger is the atomic radius.
APPEARS IN
RELATED QUESTIONS
An element P (atomic number 20) reacts with an element Q (atomic number 17) to form a compound. Answer the following questions giving reason:
Write the position of P and Q in the Modern Periodic Table and the molecular formula of the compound formed when P reacts with Q.
Write the electronic configuration of two elements X and Y whose atomic numbers are 20 and 17 respectively. Write the molecular formula of the compound formed when element X reacts with element Y. Draw the electron-dot structure of the product and also state the nature of the bond formed between both the elements.
A non-metal X which is the largest constituent of air combines with hydrogen when heated in the presence of iron as catalyst to form a gas Y. When gas Y is treated with sulphuric acid, it forms a compound Z which is used as a chemical fertiliser.
(a) What are X, Y and Z?
(b) To which group of periodic table does X belong?
(c) Name the periodic table in which X is placed.
(d) Which element is placed just before X in the period?
(e) Which element is placed just after X in the period?
Give a reason why elements need to be properly classified.
An atom of an element has the electronic configuration 2,8,2. To which group does it belong?
The elements A, B, and C belong to groups 1, 14, and 17 respectively of the Periodic Table. Which two elements will form ionic compounds?
Which of the following elements does not lose an electron easily?
Identify and name the metals out of the following elements whose electronic configurations are given below.
- 2, 8, 2
- 2, 8, 1
- 2, 8, 7
- 2, 1
Complete the following table:
| Symbol | Atomic No | Electronic Configuration | |
| 1. | He | 2 | ______ |
| 2. | Ne | ______ | 2,8 |
| 3. | Ar | ______ | 2, 8,8 |
| 4. | Na | 11 | ______ |
Identify the following:
An element in Period 1 which can be placed in both Group 1 and Group 17 of the Periodic Table.
