Mass number, atomic number and isotopes Mass number, atomic number and isotopes


In an atom the number of electrons is equal to the number of protons in the nucleus. Atoms have no overall electrical charge.

All atoms of a particular element have the same number of protons. The number of protons in an atom of an element is called its atomic number.

The total number of protons and neutrons in an atom is called its mass number.

Atoms can be represented as shown in this example:

Atoms of the same element can have different numbers of neutrons; these atoms are called isotopes of that element.

Atoms turn into positive ions if they lose one or more outer electron(s).

Students should be able to relate differences between isotopes to differences in conventional representations of their identities, charges and masses.

Ws 4.1 - Use scientific vocabulary, terminology and definitions.







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