BrainIt

Chemistry

Classification of Elements and Periodicity in Properties

The modern periodic table and its trends are the core here: atomic and ionic radii, ionization enthalpy, electron gain enthalpy, electronegativity, and valence. NEET asks you to order elements by these properties, so expect comparison questions and the standard exceptions.

Exam rules change between cycles. Confirm dates, syllabus and pattern against NTA's official site. We are not NTA.

Weightage: what the paper actually did

Classification of Elements and Periodicity in Properties carried 2 questions in the NEET 2026 paper. One paper is a data point, not a destiny: NTA moves weight between chapters every cycle, which is why the weightage tables deserve care. The stable facts are the paper's shape: 180 questions, 720 marks, +4 right, −1 wrong.

Sample PYQs from this chapter

Real questions NTA asked from Classification of Elements and Periodicity in Properties, with the answer and the working. Try before you peek.

Question 1 · NEET 2026

Identify the incorrect statement from the following:
  1. A.The largest and the smallest species among Mg, Mg2+Mg^{2+}, Al and Al3+Al^{3+} are Al and Mg2+Mg^{2+} respectively.
  2. B.The IUPAC name of the element with atomic number 107 is Unnilseptium.
  3. C.The similarity in behaviour of Li with Mg is referred to as 'diagonal relationship'.
  4. D.The oxidation state and covalency of Al in [AlCl(H2O)5]2+[AlCl(H_{2}O)_{5}]^{2+} are 3 and 6, respectively.
Answer and explanation

Answer: A

Cationic size decreases with increasing positive charge and across a period, so among Mg, Mg2+Mg^{2+}, Al and Al3+Al^{3+} the largest species is neutral Mg and the smallest is Al3+Al^{3+}, not Al and Mg2+Mg^{2+}; hence statement A is incorrect and is the answer. The others are correct: element 107 is Unnilseptium, Li and Mg show a diagonal relationship, and Al in the given complex has oxidation state +3 with covalency 6.

Question 2 · NEET 2026

The correct order of increasing metallic character of Na, Be, P, Mg and Si is:
  1. A.P<Si<Be<Mg<NaP < Si < Be < Mg < Na
  2. B.P<Si<Na<Mg<BeP < Si < Na < Mg < Be
  3. C.P<Mg<Be<Si<NaP < Mg < Be < Si < Na
  4. D.Be<Si<P<Mg<NaBe < Si < P < Mg < Na
Answer and explanation

Answer: A

Metallic character decreases across a period (left to right) and increases down a group, and it is inversely related to electronegativity. Using Pauling electronegativities (Na 0.9 < Mg 1.2 < Be 1.5 < Si 1.8 < P 2.1), metallic character increases in the reverse order: P < Si < Be < Mg < Na. Why the other options are wrong: - (B) Wrong: misplaces Na, Mg, Be. - (C) Wrong: Si should be less metallic than Be/Mg. - (D) Wrong: order is inconsistent with periodic trends.

How to practise Classification of Elements and Periodicity in Properties

Chapter by chapter, against real past-paper questions, on a screen: NEET is computer based from 2027. Read the chapter once, then attempt its PYQs until your accuracy stops climbing, and let the wrong answers tell you which lines to reread. If the chapter keeps refusing to stick, that has its own guide. There is also a free 12-question mock on the exam screen.

Nearby Chemistry chapters

Questions

How many questions did Classification of Elements and Periodicity in Properties have in NEET 2026?

Classification of Elements and Periodicity in Properties carried 2 questions in the NEET 2026 paper. Weightage shifts between cycles, so treat it as a probability, not a promise.

Where can I practise Classification of Elements and Periodicity in Properties PYQs for NEET?

In the BrainIt app, free until the 2027 exam: its bank holds 50,000 past NTA questions tagged to all 83 chapters, including this one, with accuracy tracked per chapter. Sample questions from this chapter are on this page.

Is Classification of Elements and Periodicity in Properties important for NEET 2027?

It is part of the Chemistry syllabus the paper draws from, and NEET 2027 is computer based, so practise it on a screen. Your own accuracy in the chapter matters more than any weightage table: a heavy chapter you already score well on needs less time than a light one you keep missing.

Something here wrong or out of date? Email [email protected] and a person will read it.