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

Electrons in the outer orbit are __________.

  1. nuclei

  2. waves

  3. valence

  4. holes

  5. shells
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Valence, also known as valency or valence number, is the number of valence bonds a given atom has formed or can form, with one or more atoms. For most elements the number of bonds can vary.

Multiple choice

Why is Newlands' method of classification of elements known as law of octaves?

  1. Because it could classify only eight elements

  2. Because every eighth element had the properties similar to the first

  3. Because the classification was based on the atomic masses of the element

  4. Because the elements were classified in eight groups
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to Newlands' law of octaves, when the elements are arranged in order of increasing atomic weights, then every eighth element has properties similar to that of the first element.

Multiple choice

Which of the following statements is/are not true about Mendeleev's periodic table?

(a) He started his work with 65 elements known at that time. (b) He examined the relationship between the atomic masses of the elements and their physical and chemical properties. (c) Mendeleev gave a specific position to isotopes also in his periodic table.

  1. Only (a)

  2. Only (b)

  3. Only (c)

  4. Both (a) and (c)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Both a and c are wrong. Mendeleev classified the 56 known elements of his time. No separate slot was alloted to the isotopes in Mendeleev's periodic table.  

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.