Which of the following statements is Not true about atoms?

The statement that is not true about atoms is "Atoms of all elements are identical." Atoms are the basic building blocks of matter, and they are made up of a central nucleus composed of positively charged protons and neutral neutrons, with negatively charged electrons orbiting around the nucleus. Each element has a unique number of protons in its nucleus, which is known as the atomic number. The number of protons also determines the chemical properties of the element. Therefore, the atoms of different elements are not identical, as they have different numbers of protons, neutrons, and electrons. This also means that the atoms of different elements have different atomic weights, as the atomic weight is determined by the number of protons and neutrons in the nucleus. In summary, while atoms share certain characteristics, such as having a nucleus and electrons, the atoms of different elements are not identical and have different atomic weights.