The question asks for the collective name of elements in Group 1 and Group 2 of the periodic table. This classification is based on the orbital into which the last electron enters.
A) s-Block elements — Group 1 and Group 2 elements are characterized by having their outermost electrons in the s-orbital. Group 1 elements have one valence electron (\(ns^1\)), and Group 2 elements have two valence electrons (\(ns^2\)).
The question asks for the general electronic configuration of the outermost shell of Group 1 elements, also known as alkali metals. To answer this, we need to recall the definition of Group 1 elements and their characteristic valence electron configuration.
Correct Option: D) ns¹
The general electronic configuration of the outermost shell of Group 1 elements (alkali metals) is \(ns^1\), indicating one electron in the outermost s-orbital. This single valence electron is responsible for their characteristic chemical properties, such as high reactivity and tendency to form \(+1\) ions.
To determine the general electronic configuration of Group 2 elements (alkaline earth metals), we need to recall their position in the periodic table and the principles of electron filling according to the Aufbau principle and Hund's rule.
Correct Option: B) \(ns^2\)
The general electronic configuration of the outermost shell of Group 2 elements is \(ns^2\), indicating two electrons in the outermost s-orbital.
The question asks to identify which of the given elements is NOT classified as an alkali metal (Group 1 element). To answer this, we need to recall the classification of elements in the periodic table, specifically which elements belong to Group 1 (alkali metals) and which do not.
Correct Option: A) Beryllium (Be) is not an alkali metal; it is an alkaline earth metal (Group 2 element).
The question asks to identify which of the given elements is NOT an alkaline earth metal. To answer this, we need to recall the classification of elements in the periodic table, specifically Group 2 elements (alkaline earth metals) and Group 1 elements (alkali metals).
Correct Option: D) Rubidium (Rb) is an alkali metal (Group 1 element), not an alkaline earth metal (Group 2 element).
The question asks why alkali metals are named so. This refers to the chemical properties of their hydroxides. We need to recall the definition of an alkali and the general characteristics of alkali metal hydroxides.
\[ 2\text{M(s)} + 2\text{H}_2\text{O(l)} \rightarrow 2\text{MOH(aq)} + \text{H}_2\text{(g)} \]
where \(\text{M}\) represents an alkali metal.\[ \text{NaOH(aq)} \rightarrow \text{Na}^+\text{(aq)} + \text{OH}^-\text{(aq)} \]
B) Strongly alkaline (basic) and soluble in water — This option accurately describes the properties of alkali metal hydroxides. They are strong bases (alkaline) and dissolve well in water, which is the origin of the term "alkali" for this group of metals.