Atom Basics

-An atom is the smallest unit of an element that maintains the chemical identity of that element.

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​-An element is a pure substance that cannot be broken down into simpler, stable substances and is made of one type of atom.

• ​Atoms consist of three basic particles: protons, electrons, and neutrons. The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge).

• ​These particles are also known as subatomic particles.

• ​The outermost regions of the atom are called electron shells and contain the electrons (negatively charged).

• ​Atoms have different properties based on the arrangement and number of their basic particles.

* Is the number of protons of each atom of the element.

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* ​The number of protons in an element equals the number of electrons in the element.

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* For instance, oxygen (O) has an atomic number of 8, meaning that it has 8 protons and 8 electrons.

*Is the total number of protons and neutrons that make​ up the nucleus of an element.

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​Ex: Oxygen (O) has an atomic number of 8 therefore, 8 protons and 8 neutrons. Therefore, 8 + 8 = 16.

* The number of neutrons are equal to the atomic number subtracted from the atomic mass.

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* Since the vast majority of an atom's mass is found in its protons and neutrons, subtracting the number of protons (i.e. the atomic number) from the atomic mass will give you the calculated number of neutrons in the atom.