Tag: anomalous properties of lithium

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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

Which of the following pairs shows diagonal relationship?

  1. $Na$ and $Mg$
  2. $Li$ and $Mg$
  3. $Li$ and $Na$
  4. $Al$ and $C$
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Diagonal relationship is due to:

  1. identical ionization potential

  2. identical electron negativity

  3. identical sizes of ions

  4. same valence shell configuration
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

What is the correct formula for lithium fluoride?

  1. $LiF$
  2. ${Li} _{2}{F} _{2}$
  3. ${Li} _{3}{F} _{9}$
  4. $Li{F} _{7}$
  5. ${Li} _{7}{F} _{19}$
Reveal answer Fill a bubble to check yourself
A Correct answer
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. 

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).