Name: Different Units of Temperature
Uploaded: 2019-07-19
Duration: 5 min 52 s
Description: The concept introduces the various units that are used for measuring temperature. The properties of each unit along with their interconversions are also disc...

Question

What is an atom and molecule? What is the order of magnitude of mass of atom? What are isotopes?

Accepted Answer

Atoms are the building blocks of matter. It is the neutral elementary particle which on uniting with other atoms give rise to matter. On the other hand molecule is formed by the union of two or more atoms. e.g. a molecule of water $(H_{2} O)$ is made of two atoms of hydrogen $(H)$ and one atom of oxygen $(O)$ .

The simplest atom is that of hydrogen, it contains a proton in its nucleus. The mass of proton is $1.67 \times 10^{- 27} kg$ . Therefore, the order of magnitude of mass of atom is $10^{- 27} kg$ .

Isotopes are the different atom of an element having the same atomic number (that is a same number of protons), but different mass numbers (that is, the different number of neutrons). The term is drawn from ancient Greek words 'isos' and 'topos', meaning ‘equal place’, to signify that they belong to the same elements on the periodic table.
For example, the two isotopes of Uranium, $U - 235$ and $U - 238$ , have the same atomic number $92$ , but different mass numbers of $235$ and $238$ , respectively.

What is an atom and molecule? What is the order of magnitude of mass of atom? What are isotopes?

Important Questions on Some Basic Concepts of Chemistry

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