Chemistry

Periodic Classification and Elements

1,176 Questions

Periodic classification organizes chemical elements based on atomic structure, periodic laws, and elemental properties. It covers historical classification systems, electron configurations, and periodic trends. Test takers preparing for chemistry sections will find these questions crucial for mastering fundamental element properties and atomic interactions.

Periodic table structureAtomic orbitalsElement identificationPeriodic laws

Periodic Classification and Elements Questions

Multiple choice chemistry patterns and properties of metals periodic trends in chemical properties alkali metals study of specific groups

X, Y and Z are elements in Period $3$ of the Periodic Table. The results of some experiments carried out with compounds of these elements are shown.


Element Result of adding the oxide of the element to $H _2O(l)$ Result of adding the chloride of the element of $H _2O(l)$ Result of adding the oxide of the element to $HCl(aq)$
X No reaction Hydrolyses Forms chloride salt
Y Forms hydroxide Dissolves Forms chloride salt
Z Forms acid Hydrolyses Hydrolyses


Which statement could be correct?

  1. X is Al and Y is Mg

  2. X is Si and Y is Na

  3. Y is Al and Z is P

  4. Y is Na and Z is Al
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Based on the table, Y forms a hydroxide with water (characteristic of Na or Mg), X hydrolyses (characteristic of Al or Si), and Z forms an acid (characteristic of P or S). Matching these properties, Y=Na (forms NaOH), X=Si (SiCl4 hydrolyses), and Z=P (P4O10 forms phosphoric acid) fits the data.

Multiple choice hydrides hydrogen and its compounds hydrogen chemistry

From group 6 only one metal forms hydride. This metal is:

  1. Mo

  2. W

  3. Cr

  4. Co
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The low affinity of the elements of the group $6,7,8$ and $9$ towards hydrogen in their normal oxidation states prevent the formation of hydrides. This is called as hydride gap. 

In the group, $6$, Chromium $(Cr)$ is an exception as it is the only group $6$ element to form a hydride.

Answer: $(Cr)$

Multiple choice hydrides hydrogen and its compounds hydrogen chemistry

Only one element of ________ forms hydride. 

  1. group 6

  2. group 7

  3. group 8

  4. group 9
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The only element of group $6$ i.e. Chromium $(Cr)$ forms hydride. The other elements do not form hydride due to low affinity towards hydrogen.


Answer: (A) group $6$

Multiple choice hydrides hydrogen and its compounds hydrogen chemistry

Elements of which of the following group (s) of periodic table do not form hydrides?

  1. Groups 7, 8, 9

  2. Group 13

  3. Groups 15, 16, 17

  4. Group 14
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The elements of the groups $7,8,9$ show low affinity towards hydrogen due to which they lack the tendency to form hydrides.


Answer: (A) Groups $7,8,9$

Multiple choice chemistry chemical bond and chemical equation properties of covalent compounds types of bonds and properties covalent bond

The electronic configuration of elements A, B, C, D and E are :
A (2, 8, 7)       B (2, 8, 1)       C (2)          D (2, 6)        E(2, 8)
If elements A & B combine to form a compound then its chemical formula would be _______ .

  1. $BA$
  2. $B _2A$
  3. $2BA$
  4. $BA _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the above question element A is equivalent to chlorine& B to sodium thus the structure besides shows the bonding giving rise to $NaCl$ Hence for our eg, it is $BA$.

Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

The first and last elements of actinides are:

  1. Actinium and Thorium

  2. Actinium and Nobelium

  3. Actinium and Mendelevium

  4. Actinium and Lawrencium
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

We have 15 elements in actinides. They are from atomic number 89 to 103 Actinium, Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americium, Curium, Berkelium, Californium, Einsteinium, Fermium, Mendelevium, Nobelium, Lawrencium. Hence, from these list we could say that Actinium is the first and Lawrencium is the last element in actinides.

Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

5f series elements are known as_______

  1. Lanthanides

  2. Representative elements

  3. Transition elements

  4. Actinides
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Actinides are also called the 5f series.


 Filling up of the 5f orbitals after actinium (Z = 89) gives the 5f-inner transition series known as the actinoid series.

Option D is correct.

Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

Actinoids belongs to following type of elements:

  1. s -block element

  2. d -block element

  3. f -block element

  4. p -block element
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The two rows that are generally placed underneath the main Periodic Table are called the lanthanide series and the actinide series.

These two rows are produced when electrons are being added to f orbitals.

Therefore, this block of elements are referred to as the "f block".

Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

Which of the following elements is placed just after actinide series?

  1. Rutherfordium

  2. Unnilpentium

  3. Unnilquadium

  4. Ununbium
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

Actinide series starts with actinium (Z=89) and contains fourteen elements from thorium (Z=90) to lawrencium (Z=103). This is followed by Rutherfordium (Z=104). There Rutherfordium (Z=104) also known as Unnilquadium.

Hence, both a and c are the correct option.

Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

In the general electronic configuration,
$(n-2)f^{1-14} (n-1)d^{01} ns^2$ (where n = 7) the configuration will be of:

  1. lanthenides

  2. actinides

  3. transition elements

  4. none
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

General electronic configuration is given:
$(n -2) f^{1 -14} (n -1) d^{0 1} ns^2 ,where ( n =7 )$
$5f^{1 -14} 6d^{0 1 }ns^2$
The seventh period $(n=7)$ is similar to the sixth period with the successive filling up of the 7s, 5f, 6d and 7p orbitals and includes most of the man-made radioactive elements. This period will end at the element with atomic number 118 which would belong to the noble gas family. Filling up of the 5f orbitals after actinium $(Z=89)$ gives the 5f-inner transition series known as the Actinoid Series.