Question

With reference to group 1 [IA] of the periodic table-fill in the blanks with the correct word:
The elements are ______ [light/heavy] ______ [metals/non-metals] since their atomic size is ______ [large/small]. The energy binding the atoms is ____ [high/low] and hence the elements have ______ [high/low] melting points. The melting points of elements ____ [increases/decreases] down the subgroup. The electropositive character ____ [increases/decreases] down the subgroup and the elements are strong ____ [reducing/oxidising] agents. The elements with electronic configuration 2,8,1 will have ____ [higher/lower] electron affinity and ____ [smaller/larger] atomic size than the element with electronic configuration 2,1.

Answer 1

Hint: The vertical columns in a periodic table are referred to as groups and the horizontal rows are called as periods. Group 1 [IA] of the periodic table is the first column in the periodic series. It is included in the s-block. The group 1 [IA] is also called Alkali metals as they form alkaline/basic solutions when dissolved in water. It includes a total of 7 elements.

Complete answer:
Group 1 [IA] consists of Hydrogen (H), Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Caesium (Cs) and Francium (Fr).
The valency of the group 1A is 1 as only one electron is present in the last orbit of each element. Due to this there is less attraction between the nucleus and the electron, which results in large atomic size of the elements. The group shows relatively high melting points but it lowers as we move from top to bottom in a group. As new electrons are added down the group the electropositive character rises which makes these elements to oxidise other elements. Electron affinity increases from top to bottom in a group.
Final answer-
The elements are heavy metals since their atomic size is large. The energy binding atoms are high hence the elements have a high melting point. The melting points of elements decrease down the sub group. The electropositive character increases down the sub group and the elements are strong oxidizing agents. The element with electronic configuration 2,8,1 will have higher electron affinity and smaller atomic size than the element with electronic configuration 2,1.

Note:
 Group 1A consists of highly reactive metals as they react vigorously with water. Sodium and potassium are stored in kerosene and lithium is stored in oil.