Atoms that have the same atomic number but different atomic masses are called isotopes. The difference in mass arises due to the atoms containing a different number of neutrons for the same number of protons.Know More
The identity of an element is determined by the number of protons each of its nuclei contains. Protons are positively charged and held together in a small space. The electrostatic force of repulsion between the like charges is very high, but they are able to remain stable due to the presence of neutrons. Neutrons are neutral subatomic particles found within the nucleus of an atom. The protons and neutrons are the heaviest subatomic particles and constitute the entire atomic mass of an element.
When two atoms have the same number of protons, they are said to be from the same element. However, if they differ in atomic mass, it means that the number of neutrons in the nuclei is different for the two atoms. Since the number of neutrons does not change the electron configuration of the atoms, the two atoms have the same chemical properties. However, they have different physical properties, such as boiling point, melting point and density, because their atomic masses are different.
To account for the similarities in chemical properties but the difference in physical properties, the two atoms of the same element are called isotopes of that element. For example, hydrogen has two other isotopes, deuterium and tritium, caused by the addition of extra neutrons in the nucleus without a change in the number of protons or electrons.Learn more about Atoms & Molecules
In 1905, Albert Einstein published an analysis in which he devised a mathematical way to predict the size of both atoms and molecules. At the time, the science of atoms was still in its infancy, but Einstein's test was crucial in leading the way towards testing the reality of atoms.Full Answer >
Dalton's atomic theory states four critical truths about atoms: firstly, everything is made up of atoms and atoms cannot be destroyed. Secondly, all atoms within a single element are identical. Thirdly, compounds are formed from two or more different kinds of atoms. Finally, chemical reactions rearrange atoms.Full Answer >
The atomic theory formulated by the British chemist John Dalton proposes that atoms are indivisible particles comprising all matter; atoms of the same element share identical properties, including shape, size and mass; atoms of an element are unique and vary from the atoms of different elements; atoms are the fundamental units of a chemical reaction; atoms are conserved and can neither be created nor destroyed; and atoms combine in simple, fixed proportions to produce compound atoms, known as molecules. Dalton is commonly referred to as the father of the modern atomic theory.Full Answer >
No, not all atoms of the same element are identical. Contrary to Dalton’s theory — that atoms of the same element are identical — scientists discovered that atoms comprise smaller sub-atomic particles. Further experiments revealed fundamental particles beyond neutrons, protons and electrons. Although an atom is the tiniest particle of an element that retains the element’s intrinsic properties, all 92 stable atoms are composed of only three smaller, more fundamental particles.Full Answer >