Editing Chemistry (section)

====Atom====
{{Main|Atom}}
[[File:Atom Diagram.svg|thumb|upright=0.75|left|A diagram of an atom based on the [[Rutherford model]]]]

The [[atom]] is the basic unit of chemistry. It consists of a dense core called the [[atomic nucleus]] surrounded by a space occupied by an [[electron cloud]]. The nucleus is made up of positively charged [[protons]] and uncharged [[neutrons]] (together called [[nucleon]]s), while the [[electron]] cloud consists of negatively charged [[electron]]s which orbit the nucleus. In a neutral atom, the negatively charged electrons balance out the positive charge of the protons. The nucleus is dense; the mass of a nucleon is approximately 1,836 times that of an electron, yet the radius of an atom is about 10,000 times that of its nucleus.{{sfn|Burrows|Holman|Parsons|Pilling|2009|p=13}}{{sfn|Housecroft|Sharpe|2008|p=2}}

The atom is also the smallest entity that can be envisaged to retain the [[chemical properties]] of the element, such as [[electronegativity]], [[ionization potential]], preferred [[oxidation state]](s), [[coordination number]], and preferred types of bonds to form (e.g., [[metal]]lic, [[ion]]ic, [[covalent]]).