Tag: the s-block elements (alkali and alkaline earth metals)

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Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

$Li$ and $Mg$ resembles each other because

  1. both are s-block elements

  2. both are metals

  3. both have almost same periodic properties

  4. they have same electronic configuration
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Due to its small size, lithium differs from other alkali metals but resembles with Mg as its size and other periodic properties are closer to Mg. Its resemblance with Mg is known as diagonal relationship.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

Correct relation for the size of $Li$ and $Mg$ is:

  1. $Mg>>Li$
  2. $Mg>Li$
  3. $Mg=Li$
  4. $Mg<Li$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Size of Mg is less than that of Li because of the $Z _{eff}$ of Mg. As the protons are added, electrons are attracted with a greater strength towards the core, making the radius of Mg smaller. 

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

Which of the following will produce $CO _2$ on heating?

  1. $BaCO _3$
  2. $Na _2CO _3$
  3. $MgCO _3$
  4. $CaCO _3$
Reveal answer Fill a bubble to check yourself
C,D Correct answer
Explanation

Carbonates of $Li$, $Ca$ $Mg$ decompose on heating and liberate $CO _2$.Carbonates of other alkali metals are stable towards heat and decomposed only by fusion. 

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

${Li} _{2}{SO} _{4}$ is not isomorphous with sodium sulphate, due to:

  1. small size of lithium

  2. high coordination number of lithium

  3. high ionization energy of lithium

  4. none of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Isomorphic compounds have same crystal structure at given temperature and conditions. While $LiSO _4$ and $Na _2SO _4$ are not isomorphous due to the exceptionally small size of Lithium (Li).

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

The first element of the groups 1 and 2 are different from other members of the respective groups. Their behaviour is more similar to the second element of the following groups. What is this relationship known as?

  1. Anomalous relationship

  2. Periodic relationship

  3. Diagonal relationship

  4. Chemical relationship
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The similarities (in many of properties) between first element of a group and second element of the next group is called diagonal relationship.
Thus, Li ( first element of group 1) shows diagonal relationship with Mg (second element of group 2).
Also, Be ( first element of group 2) shows diagonal relationship with Al (second element of group 13).
Also, B ( first element of group 13) shows diagonal relationship with Si (second element of group 14).
Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

Which of the following does not show the anomalous behaviour of Lithium?

  1. Lithium reacts with nitrogen to form a nitride

  2. Lithium carbonate decomposes on heating
  3. Lithium nitrate gives $NO _2$ on heating

  4. Lithium is the strongest reducing agent
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Anomalous behavior of lithium is due to extremely small size of lithium. Its cation on account of small size and high nuclear charge, lithium exerts the greatest polarizing effect out of all alkali metals on the negative ion. Consequently, lithium ion possesses a remarkable tendency towards solvation and develops a covalent character in its compounds.

But lithium like other metals of the same group is a strong reducing agent. In fact, Lithium is the strongest reducing agent in aqueous solution.

Thus option D is correct.
Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

The properties of $Li$ are similar to those of $Mg$. This is because:

  1. both have nearly the same size.

  2. both has their charge to size ratio nearly the same.

  3. both have similar electronic configurations.

  4. both are found together in nature.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • The properties of lithium are similar to those of $Mg$ because they are having diagonal relationship.
  • The elements having diagonal relationship show similar properties and the reason is because the both of them will have similar electronegativity and polarising power i.e. charge per size ratio of both the elements are nearly the same.
Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

Choose the correct answer form the alternatives given.
Which of the following statements is not true about alkali metals ?

  1. All alkali metals from oxo salts such as carbonates, sulphates and nitrates.

  2. The basic character of oxides increases down the group.

  3. Carbonates and sulphates of lithium are stable and their stability decreases down the group.

  4. Solubility of carbonates and sulphates increases down the group.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Characteristics of Alkali Metals-
  • Found in column 1A of the periodic table.
  • Have one electron in their outermost layer of electrons.
  • Easily ionized.
  • Silvery, soft, and not dense.
  • Low melting points.
  • Incredibly reactive.
  • They form oxo salts such as carbonates, sulphates and nitrates.
  • The basic character of oxides increases down the group.
  • The acidic character of oxides decreases down the group.
  • Solubility of carbonates and sulphates increases down the group.
  • As we move down the alkali metal group, the electropositive character increases. This causes an increase in the stability of alkali carbonates. However, lithium carbonate is not so stable to heat. This is because lithium carbonate is covalent.
  • Hence option C is not correct about alkali metals.