Chemistry

Periodic Classification and Elements

1,092 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

Which of the following pairs of atoms shows inert pair effect?

  1. Ge and As

  2. Sn and Ge

  3. Sn and Pb

  4. As and Sn

  5. Pb and Ge
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Some of the heavier elements/atoms, which are having three or four electrons in the outermost shell are expected to form di, tri or tetravalent ions, but sometimes they do not lose electrons and hence, form cations with lower positive charge. Such electrons which do not participate in ion formation are called inert parts. This effect is known as inert pair effect. Probably, this effect takes place when n = 4 or > 4 only. Sn (Z = 50) = [Kr] 4d10, 5s2, 5p2 Sn2+ = [Kr] 5d10, 5s2, 5p0 Pb (Z = 82) = [Xe] 5d10, 6s2, 6p2 In Sn2+, 5s2 is an inert pair which does not take part in ion formation. Pb2+ = [Kr] 5d10, 6s2, 6p0 In Pb2+, 6s2 is an inert pair which does not take part in ion formation.

Multiple choice

Identify the isotonic species in the given sets.

  1. 30Zn68, 31Ga71, 32Ge70

  2. 32Ge70, 30Zn68, 31Ga69

  3. 32Ge72, 31Ga71, 30Zn66

  4. 30Zn66, 31Ga69, 32Ge70

  5. 31Ga69, 30Zn64, 32Ge72
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Isotonic species: The atomic species in which number of neutrons is the same. 32Ge70, 30Zn68 and 31Ga69 all have 38 neutrons. Hence, these are isotonic species.

Multiple choice

Glass has the elements

  1. Hg, Si, O2 and N2

  2. Na, Si and O2

  3. H2, O2 and C

  4. Si, C and O2
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Glass is made of sodium, silicon and oxygen.

Multiple choice

The principal quantum number ‘n’ represents

  1. size of the orbital

  2. angular momentum of an electron

  3. shape of the orbital

  4. spin of the electron
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The principal quantum number ‘n’ represents the size of the orbital.

Multiple choice

The element with the maximum electron affinity is

  1. N

  2. H

  3. He

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

Electron affinity is defined as the change in energy (in kJ/mole) of a neutral atom (in the gaseous phase) when an electron is added to the atom to form a negative ion. Halogens have the greatest electron affinity as by gaining one electron, they attain noble gas configuration. Thus, from the given elements, fluorine has the maximum electron affinity.

Multiple choice

The electronic configuration of chromium (Z = 24) is

  1. 1s2, 2s2, 2p6, 3s2, 3p6, 3d4, 4s2

  2. 1s2, 2s2, 2p6, 3s2, 3p6, 3d5, 4s1

  3. 1s2, 2s2, 2p6, 3s2, 3p6, 3d6, 4s0

  4. 1s2, 2s2, 2p6, 3s2, 3p6, 3d4
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The electronic configuration of chromium (Z = 24) is 1s2, 2s2, 2p6, 3s2, 3p6, 3d5, 4s1.