Which one among the following statements about an atom is not correct ?

Statement 1 is incorrect because atoms do not always combine to form molecules. While atoms of many elements like hydrogen and oxygen are unstable and must combine to exist [3], atoms of noble gases (like helium or neon) and certain metals like gold and iron can exist as individual atoms or in metallic lattices rather than discrete molecules [1]. Statement 2 is correct as atoms are indeed the building blocks for molecules and ions [1]. Statement 3 is generally considered correct in a fundamental sense because an 'atom' by definition has an equal number of protons and electrons, resulting in no net charge; when it gains or loses electrons, it is specifically termed an 'ion' [2]. Statement 4 is correct as the aggregation of vast numbers of atoms forms the macroscopic matter we interact with [1].

Sources

1. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 7: Particulate Nature of Matter > A step further > p. 115
2. [3] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 8: Nature of Matter: Elements, Compounds, and Mixtures > A step further > p. 123
3. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 25: Thunderstorm > 25.4. Lightning And Thunder > p. 348