ATOMS AND MOLECULES - A BRIEF STUDY

Atom is a smallest particle of an element that can enter into a chemical combination with another element. Thus it an ultimate building block of matter.

A molecule on the other hand is the smallest particle of an element (or compound) that can stay independently.

A molecule consists of one atom is called monoatomic ( e . g , rare gases ).

A molecule consists of two atoms is called diatomic ( E . g , Hydrogen , Nitrogen , Oxygen ).

Polyatomic molecules

A molecule Consists of more than two atoms is called polyatomic molecules. ( E . g , Phosphorus )

A nucleus of an atom consists of protons and neutrons.

Nucleus

A proton has positive charge (1+) and a neutron though having almost the same weight of a proton is neutral in charge.

Much Smaller particles known as electrons move around the nucleus. A electron is having the same magnitude of charge of a proton with opposite sign.

Nucleus diameter is about 10 ^ -5 nanometer while atomic diameter about 10 ^ -1 nanometer.

The number of protons in a nucleus equals to its atomic number.

The mass number of an atom equals to the combined number of protons and neutrons of an atom. Each element is assigned a symbol derived from its name. For example O is the symbol of oxygen.

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Mechinopedia For Mechanical Engineers

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