Tag: anomalous properties of lithium

Questions Related to anomalous properties of lithium

Which of the following pairs shows diagonal relationship?

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

  1. $Na$ and $Mg$

  2. $Li$ and $Mg$

  3. $Li$ and $Na$

  4. $Al$ and $C$

Show answer
Correct Option: B
Explanation:

A diagonal relationship is said to exist between certain pairs of diagonally adjacent elements in the second and third periods of the periodic table. Thus, $Li$ and $Mg$ are diagonally related.

Diagonal relationship is due to:

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

  1. identical ionization potential

  2. identical electron negativity

  3. identical sizes of ions

  4. same valence shell configuration

Show answer
Correct Option: C
Explanation:

Option $(C)$ is correct.

The diagonal relationship is due to identical sizes of ions.
On moving rightward a period of the periodic table, the size of the atoms decreases, and on moving down a group the size of the atoms increases. Similarly, on moving rightward a period, the elements become more electronegative, whereas on moving down the group the element becomes more positive. These two factors work in opposite direction. Hence the elements that are present diagonally to each other have similar properties like atomic size, electronegativity, density, chemical properties of compounds.

What is the correct formula for lithium fluoride?

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

  1. $LiF$

  2. ${Li} _{2}{F} _{2}$

  3. ${Li} _{3}{F} _{9}$

  4. $Li{F} _{7}$

  5. ${Li} _{7}{F} _{19}$

Show answer
Correct Option: A
Explanation:

$LiF$ is the correct formula for lithium fluoride. $Li$ has a +1 charge and $F$ has a -1 charge so, when they come together, to form $LiF$ having an ionic bond. 

Which among the following is completely soluble in water?

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

  1. $NaF$

  2. $MgF$

  3. $LiF$

  4. $Mg _3(PO _4) _2$

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Correct Option: A
Explanation:

Fluorides and phosphates of $Li$ and $Mg$ are sparingly soluble in water whereas those of other alkali metals are soluble in water.

$Li$ and $Mg$ resembles each other because

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

  1. both are s-block elements

  2. both are metals

  3. both have almost same periodic properties

  4. they have same electronic configuration

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Correct Option: C
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.

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

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

  1. $Mg>>Li$

  2. $Mg>Li$

  3. $Mg=Li$

  4. $Mg<Li$

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Correct Option: D
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. 

Which of the following will be sparingly soluble in water?

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

  1. $Ca _3(PO _4) _2$

  2. $CaF _2$

  3. $Mg _3(PO _4)2$

  4. $NaF$

Show answer
Correct Option: C
Explanation:

 Fluorides and phosphates of $Li$ and $Mg$ are sparingly soluble in water whereas those of other alkali metals are soluble in water.

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

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

  1. $BaCO _3$

  2. $Na _2CO _3$

  3. $MgCO _3$

  4. $CaCO _3$

Show answer
Correct Option: C,D
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. 

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

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

  1. small size of lithium

  2. high coordination number of lithium

  3. high ionization energy of lithium

  4. none of the above

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Correct Option: A
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).

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?

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

  1. Anomalous relationship

  2. Periodic relationship

  3. Diagonal relationship

  4. Chemical relationship

Show answer
Correct Option: C
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).