Mix Examples - Periodic Classification of Elements Questions in English

(C) The Modern Periodic Table is organized based on the atomic number of elements.
It consists of $7$ horizontal rows,which are called Periods.
It consists of $18$ vertical columns,which are called Groups.
Therefore,the statement that it has $18$ vertical columns known as Groups is correct.

(D) To determine the period of an element,we look at its electronic configuration.
$A$ (Atomic number $2$): Configuration is $2$ ($K$-shell). It belongs to Period $1$.
$B$ (Atomic number $3$): Configuration is $2, 1$. It belongs to Period $2$.
$C$ (Atomic number $7$): Configuration is $2, 5$. It belongs to Period $2$.
$D$ (Atomic number $10$): Configuration is $2, 8$. It belongs to Period $2$.
$E$ (Atomic number $30$): Configuration is $2, 8, 18, 2$. It belongs to Period $4$.
Elements with the same number of shells belong to the same period.
Elements $B, C,$ and $D$ all have $2$ shells,so they belong to Period $2$.

(A) To determine if elements belong to the same group,we must write their electronic configurations:
$A$ (atomic number $9$): $2, 7$ (Group $17$)
$B$ (atomic number $11$): $2, 8, 1$ (Group $1$)
$C$ (atomic number $17$): $2, 8, 7$ (Group $17$)
$D$ (atomic number $12$): $2, 8, 2$ (Group $2$)
$E$ (atomic number $13$): $2, 8, 3$ (Group $13$)
Elements with the same number of valence electrons belong to the same group.
Here,$A$ and $C$ both have $7$ valence electrons,so they belong to the same group (Group $17$).

(B) The electronic configuration of the element is $2, 8$.
This indicates that the element has $2$ shells ($K$ and $L$ shells).
The valence shell ($L$ shell) is completely filled with $8$ electrons,which represents a stable octet configuration.
Elements with a completely filled valence shell are classified as noble gases.
In the Modern Periodic Table,all noble gases are placed in Group $18$.

(C) All organic compounds are based on carbon chains or rings.
Carbon is the fundamental element that forms the backbone of all organic molecules.
Carbon has an atomic number of $6$ and its electronic configuration is $2, 4$.
It belongs to Group $14$ of the periodic table,which is the carbon family.

(D) The period number of an element corresponds to the number of shells present in its atom.
For elements in period $2$,the electrons are filled in the first two shells.
The first shell is the $K$ shell $(n=1)$,and the second shell is the $L$ shell $(n=2)$.
Since the period is $2$,the $L$ shell is the outermost shell for these elements.

(A) Metallic character refers to the tendency of an element to lose electrons.
In a group,metallic character increases as we move down because the atomic size increases and the valence electrons are held less tightly by the nucleus.
In a period,metallic character decreases from left to right because the atomic size decreases and the effective nuclear charge increases,making it harder to lose electrons.
For option $A$: $Be, Mg, Ca$ are all in Group $2$. As we move down the group from $Be$ to $Mg$ to $Ca$,the metallic character increases.
For option $B$: $Li$ is in Period $2$,while $Na$ and $K$ are in Period $3$ and $4$ respectively. The order $Na, Li, K$ is not increasing.
For option $C$: $Mg, Al, Si$ are in the same period. Metallic character decreases from $Mg$ to $Si$.
For option $D$: $C, N, O$ are in the same period. Metallic character decreases from $C$ to $O$.
Therefore,the correct set is $Be, Mg, Ca$.

(B) Mendeleev predicted the existence of several elements that had not been discovered at that time.
He named them by prefixing a Sanskrit numeral 'Eka' to the name of the preceding element in the same group.
For example,he named 'Eka-silicon' to the element that was discovered later and named 'Germanium'.
Therefore,Germanium is the element that found a place in the periodic table later.

(FALSE) The statement is False. John Newlands assumed that only $56$ elements existed in nature and that no more elements would be discovered in the future. The number $63$ is associated with the number of elements known at the time of Mendeleev's Periodic Table.

(B) The statement is False. In Newlands' Law of Octaves,he adjusted two elements in the same slot (e.g.,cobalt and nickel) to fit elements into his table,but he did not put three elements in the same slot. Furthermore,he did place some unlike elements in the same slot,but the claim regarding 'three elements' is incorrect.

(TRUE) The statement is True. Mendeleev's periodic law states that the properties of elements are a periodic function of their atomic masses. He arranged the elements in increasing order of their atomic masses and observed that elements with similar physical and chemical properties repeat after regular intervals.

(FALSE) The statement is False.
Hydrogen has an electronic configuration of $1s^1$,which means it has one valence electron in its outermost shell.
Alkaline earth metals (Group $2$ elements) have a general valence shell electronic configuration of $ns^2$,meaning they have two valence electrons.
Hydrogen's configuration actually resembles that of alkali metals (Group $1$),which have a general valence shell configuration of $ns^1$.

(FALSE) The statement is False. It was Henry Moseley,not Dmitri Ivanovich Mendeleev,who demonstrated in $1913$ that the atomic number of an element is a more fundamental property than its atomic mass. Mendeleev's periodic law was based on atomic mass.

(FALSE) The statement is False.
In the Modern periodic table,the third period consists of elements with atomic numbers $11$ to $18$,which are $Na, Mg, Al, Si, P, S, Cl$ and $Ar$.
$Li$ (Lithium) has an atomic number of $3$ and belongs to the second period,while $F$ (Fluorine) has an atomic number of $9$ and also belongs to the second period.

(B) The statement is False.
Atomic size (or atomic radius) is defined as the distance between the centre of the nucleus and the outermost shell (valence shell) of an isolated atom,not the penultimate shell.

(TRUE) The statement is True. In the Modern Periodic Table,a zig-zag line (often referred to as the staircase line) effectively separates the metallic elements on the left from the non-metallic elements on the right. The elements lying along this boundary,such as boron $(B)$,silicon $(Si)$,germanium $(Ge)$,arsenic $(As)$,antimony $(Sb)$,tellurium $(Te)$,and polonium $(Po)$,exhibit properties that are intermediate between those of metals and non-metals. These elements are collectively known as metalloids or semimetals.

(A) The statement is True.
$1$. Metallic character is the tendency of an element to lose electrons.
$2$. Across a period,the effective nuclear charge increases,which pulls the valence electrons closer to the nucleus,making it harder to lose them; thus,metallic character decreases.
$3$. Down a group,the number of shells increases,which decreases the effective nuclear charge experienced by valence electrons due to increased shielding,making it easier to lose electrons; thus,metallic character increases.

(A) The statement is $True$.
Non-metals have a high tendency to attract electrons due to their high electronegativity.
They typically gain electrons to complete their valence shells,forming anions or covalent bonds.
In the periodic table,electronegativity increases from left to right across a period and decreases down a group.
Consequently,non-metals are located on the right-hand side of the periodic table,particularly towards the top,where electronegativity values are highest.