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Although the word "atom" comes from the Greek term for indivisible, ''átomos'', atoms are actually made up of three different kinds of subatomic particles; some of these are composed of yet smaller particles.

Although the word "atom" comes from the Greek term for indivisible, ''átomos'', atoms are actually made up of three different kinds of subatomic particles; some of these are composed of yet smaller particles.

In the atomic [[nucleus]] there are positively charged [[proton]]s and electrically neutral [[neutron]]s. Spinning around the nucleus are negatively charged [[electron]]s. [[Hydrogen]], in its most common [[isotope]], has only one proton and no neutrons.

In the atomic [[nucleus]] there are positively charged [[proton]]s and electrically neutral [[neutron]]s. Surrounding the nucleus are negatively charged [[electron]]s. [[Hydrogen]], in its most common [[isotope]], has only one proton and no neutrons.

Protons and neutrons are comprised of [[quark]]s and are contained closely together in the center of an atom, forming the [[nucleus]]. Electrons move in the space around the nucleus, and are arranged around it in a series of layers, known as [[electron shell|shells]] or energy levels. Since protons and neutrons are approximately 2000 times as heavy as electrons, the vast majority of an atom's mass is found in the nucleus. Currently quarks and electrons are considered truly elementary particles. Atoms are mostly empty space, as the relative size of the nucleus compared to the area of the lowest electron shell is about that of a pea in a stadium. Another common analogy for the atom along the same lines is the "fly in the cathedral", where the cathedral is the whole atom and the fly is the nucleus.  

Protons and neutrons are comprised of [[quark]]s and are contained closely together in the center of an atom, forming the [[nucleus]]. Electrons move in the space around the nucleus, and are arranged around it in a series of layers, known as [[electron shell|shells]] or energy levels. Since protons and neutrons are approximately 2000 times as heavy as electrons, the vast majority of an atom's mass is found in the nucleus. Currently quarks and electrons are considered truly elementary particles. Atoms are mostly empty space, as the relative size of the nucleus compared to the area of the lowest electron shell is about that of a pea in a stadium. Another common analogy for the atom along the same lines is the "fly in the cathedral", where the cathedral is the whole atom and the fly is the nucleus.  

Those who understand electrical theory might notice that positively charged particles packed closely together would repel one another. The nucleus stays together because of what is known as the ''strong nuclear force''. The quantization of this force is a tiny particle called a "gluon".  

Those who understand electrical theory might notice that positively charged particles packed closely together would repel one another. The nucleus stays together because of what is known as the ''strong nuclear force''. The quantization of this force is a particle called a "[[gluon]]".

 

==Atomic Number==

==Atomic Number==

[[Image:Isotopes.jpg|right|thumb|Isotopes]]

[[Image:Isotopes.jpg|right|thumb|Isotopes]]

==Isotopes==

==Isotopes==

Atoms of the same element that have different numbers of neutrons are known as [[isotope]]s. Some isotopes are more stable than others, and occur more often in nature, but there is no "standard" number of neutrons in a given element. The atomic weight of an element is a weighted average of the number of neutrons and protons (number of protons remains constant in a given element) in all naturally occurring isotopes. Many isotopes are [[radioactive]] and [[decay]] over time.

Atoms of the same element that have different numbers of neutrons are known as [[isotope]]s. Some isotopes are more stable than others, and occur more often in nature, but there is no "standard" number of neutrons in a given element. The atomic weight of an element is a weighted average of the number of neutrons and protons (number of protons remains constant in a given element) in all naturally occurring isotopes. Many isotopes are [[radioactive]] and [[radioactive decay|decay]] over time.

==See also==

==See also==