Changes

An '''atom''' is

An '''atom''' is

a [[particle]] of [[matter]] indivisible by [[chemical]] means <ref>[http://www.lbl.gov/abc/Glossary.html Glossary of Nuclear Terms] </ref> which form the building blocks of molecules.

a [[particle]] of [[matter]] indivisible by [[chemical]] means <ref>[http://www.lbl.gov/abc/Glossary.html Glossary of Nuclear Terms] </ref> which form the building blocks of molecules.

The word atom comes from the Greek term for indivisible, ''átomos''.

Although the word "atom" comes from the Greek term for indivisible, ''átomos'', atoms are actually made up of three different kinds of subatomic 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.

Atoms are comprised of three subatomic particles: positively charged [[proton]]s, electrically neutral [[neutron]]s and negatively charged [[electron]]s. Protons and neutrons are comprised of quarks and are contained closely together in the center of an atom, forming the [[nucleus]]. Electrons inhabit 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 quarks and are contained closely together in the center of an atom, forming the [[nucleus]]. Electrons inhabit 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 tiny particle called a "gluon".