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An element ‘X’ belongs to 3rd period and group 16 of the Modern Periodic Table.
a. Determine the number of valence electrons and the valency of ‘X’.
b. Molecular formula of the compound when ‘X’ reacts with hydrogen and write its electron dot structure.
c. Name the element ‘X’ and state whether it is metallic or non-metallic.
An element ‘X’ (Atomic number = 20) burns in the presence of oxygen to form a basic oxide.
a. Identify the element and write its electronic configuration.
b. State its group number and period number in the Modern Periodic Table.
C. Write a balanced chemical equation for the reaction when this oxide is dissolved in water.
The elements of a period of the periodic table are given in order from left to right with one of its element missing:
a. To which period do these elements belong?
b. One element of this period is missing. Which is the missing element and where should it be placed?
c. Which one of these elements in this period shows the property of catenation?
d. Which one of these elements is least reactive?
The position of some elements A,B,C,D,E,F and G in the Modern Periodic Table is given as under:
a. In which group are inert elements placed?
b. What type of ions would B, C, E and F form?
c. Which elements would have chemical properties similar to C?
d. How many shells would A have?
e. What is the similarity between A and D?
f. Identify the most abundant element in the earth’s crust.
a. The following is a list of the electron distributions of atoms of unknown elements.
Choose an element from the list for each of the following descriptions.
i. It is a noble gas.
ii. It is a soft metal with a low density.
iii. It has giant covalent structure similar to diamond.
iv. It can form a negative ion of the type X3-.
b. How does electronic configurations of atoms change in a period with increase in atomic number?