Skip to main content

s-block Class 11

                                S Block Class

name of the chapter: S block class

Content Provider: FIITJEE

Lecturer from FIITJEE


Introduction based on NCERT:

The s-block elements of the Periodic Table are those in which the last electron enters the outermost s-orbital. As the s-orbital can accommodate only two electrons, two groups (1 & 2) belong to the s-block of the Periodic Table. Group 1 of the Periodic Table consists of the elements: lithium, sodium, potassium, rubidium, cesium and francium. They are collectively known as alkali metals. These are so-called because they form hydroxides on reaction with water which are strongly alkaline in nature. The elements of Group 2 include beryllium, magnesium, calcium, strontium, barium, and radium. These elements with the exception of beryllium are commonly known as alkaline earth metals. These are so-called because their oxides and hydroxides are alkaline in nature and these metal oxides are found in the earth’s crust*. Among the alkali metals, sodium and potassium are abundant and lithium, rubidium, and caesium have much lower abundances (Table 10.1). Francium is highly radioactive; its longest-lived isotope 223Fr has a half-life of only 21 minutes. Of the alkaline earth metals, calcium and magnesium rank fifth and sixth in abundance respectively in the earth’s crust. Strontium and barium have much lower abundances. Beryllium is rare and radium is the rarest of all comprising only 10–10 percent of igneous rocks† (Table 10.2, page 299). The general electronic configuration of s-block elements is [noble gas]ns1 for alkali metals and [noble gas] ns 2 for alkaline earth metals.

Lithium and beryllium, the first elements of Group 1 and Group 2 respectively exhibit some properties which are different from those of the other members of the respective group. In these anomalous properties, they resemble the second element of the following group. Thus, lithium shows similarities to magnesium and beryllium to aluminum in many of their properties. This type of diagonal similarity is commonly referred to as diagonal relationship in the periodic table. The diagonal relationship is due to the similarity in ionic sizes and /or charge/radius ratio of the elements. Monovalent sodium and potassium ions and divalent magnesium and calcium ions are found in large proportions in biological fluids. These ions perform important biological functions such as maintenance of ion balance and nerve impulse conduction.


Embedded pdf:

Comments

Post a Comment

Popular posts from this blog

Purification Characterisation of Organic Compounds class 11

  Purification  Characterisation of Organic Compounds  name of the chapter:  Purification  Characterisation of Organic Compounds  Content Provider: FIITJEE Lecturer from FIITJEE simple notes: Organic compounds extracted from a natural source or synthesized in the laboratory require purification. Various methods are used for purification and are based on the nature of the compound and the impurity present in it. The purity of a compound is ascertained by determining its melting point or boiling point or by chromatographic and spectroscopic techniques. Fraction distillation  can be defined as a process where the separation of a mixture takes place. A mixture of various components such as chemical components can be easily vaporized by heating them to a temperature more than their boiling point and forming different fractions. embedded pdf:
Post a Comment
Read more

acids bases and salts pptx

 Acids Bases and Salts PPT   name of the chapter:       acids bases and salts Content Provider:            Student ( Dharani ) Acid Bases and Salts introduction by NCERT : You already know that acids are sour in taste and change the colour of blue litmus to red, whereas, bases are bitter and change the colour of the red litmus to blue. Litmus is a natural indicator, turmeric is another such indicator. Have you noticed that a stain of curry on a white cloth becomes reddish-brown when soap, which is basic in nature, is scrubbed on it? It turns yellow again when the cloth is washed with plenty of water. You can also use synthetic indicators such as methyl orange and phenolphthalein to test for acids and bases. In this chapter, we will study the reactions of acids and bases, how acids and bases cancel out each other’s effects and are much more interesting things that we use and see in our day-to-day life. Do Y...
Post a Comment
Read more

Molar Mass and Atomic Mass and first 20 elements

 Molar Mass and Atomic Mass and first 20 elements  Molar Mass : In chemistry, the molar mass of a chemical compound is defined as the mass of a sample of that compound divided by the amount of substance in that sample, measured in moles. It is the mass of 1 mole of the substance or 6.022×10²³ particles, expressed in grams.   Atomic mass: The  atomic mass  is a weighted average of all of the isotopes of that element, in which the  mass  of each isotope is multiplied by the abundance of that particular isotope. ( Atomic mass  is also referred to as  atomic weight , but the term " mass " is more accurate.) Calculating Average  Atomic Mass:  Average  atomic mass  = f 1 M 1  + f 2 M 2  +… + f n M n  where f is the fraction representing the natural abundance of the isotope and M is the  mass  number (weight) of the isotope. The average  atomic mass  of an element can be found on th...
Post a Comment
Read more