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प्रश्न
The atomic numbers of the elements Na, Mg, K and Ca are 11, 12, 19 and 20 respectively. The element having the largest atomic radius is:
(a) Mg
(b) Na
(c) K
(d) Ca
उत्तर
K.
Potassium (K) with an atomic number of 19 has the largest atomic radius. This is because sodium and potassium are elements of group 1. On moving from top to bottom in a group, the atomic radius increases. Magnesium and calcium are elements of group 2. The size of the atomic radius decreases on moving from left to right in a period of the periodic table .
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संबंधित प्रश्न
How do the atomic size and metallic character of elements vary as we move :-
(a) down a group and
(b) from left to right in a period
Consider two elements 'A' (Atomic number 17) and 'B' (Atomic number 19) :
(i) Write the positions of these elements in the modern periodic table giving justification.
(ii) Write the formula of the compound formed when 'A' combines with 'B.'
(iii) Draw the electron dot structure of the compound and state the nature of the bond formed between the two elements.
Which element has twice as many electrons in its second shell as in its first shell?
In the following set of element, one element does not belong to the set. Select this element and state why it does not belong:
Calcium, Magnesium, Sodium, Beryllium
What happens to the metallic character of the elements as we move from left to right in a period of the periodic table?
What is its atomic number?
F, Cl and Br are the elements each having seven valence electrons. Which of these (i) has the largest atomic radius, (ii) is most reactive? Justify your answer stating reason for each.
Name and state the following with reference to the elements of the first three periods of the periodic table.
Metalloid in Period 3.
Based on the group valency of element write the molecular formula of the following compound giving justification:
Oxide of first group elements.
Name the elements in the correct order of their increasing atomic numbers present in the first, second, and third short periods of the periodic table.
State which of the elements are –
- metallic
- non-metallic
- noble gases
in each of the periods 2 and 3.
