Space-filling model
Overview
 
In chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

 a space-filling model, also known as calotte model, is a type of three-dimensional molecular model
Molecular model
A molecular model, in this article, is a physical model that represents molecules and their processes. The creation of mathematical models of molecular properties and behaviour is molecular modelling, and their graphical depiction is molecular graphics, but these topics are closely linked and each...

 where the atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s are represented by spheres whose radii are proportional to the radii of the atoms and whose center-to-center distances are proportional to the distances between the atomic nuclei
Atomic nucleus
The nucleus is the very dense region consisting of protons and neutrons at the center of an atom. It was discovered in 1911, as a result of Ernest Rutherford's interpretation of the famous 1909 Rutherford experiment performed by Hans Geiger and Ernest Marsden, under the direction of Rutherford. The...

, all in the same scale. Atoms of different chemical element
Chemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...

s are usually represented by spheres of different colors.

Calotte models are distinguished from other 3D representations, such as the ball-and-stick
Ball-and-stick model
In chemistry, the ball-and-stick model is a molecular model of a chemical substance which is to display both the three-dimensional position of the atoms and the bonds between them...

 and skeletal models, by the use of "full size" balls for the atoms. They are useful for visualizing the effective shape and relative dimensions of the molecule, in particular the region of space occupied by it.
Quotations

A Camel is a Horse designed by committee.

Accept nothing, challenge everything.

Act quickly... but not too quickly.

Actions speak louder than words.

A guitarist is only as good as his drummer and bassist

A man’s libido is nine-tenths testosterone.

A proof tells us where to concentrate our doubts.

A rolling stone gathers no moss, so there’s nothing to cushion the impact when it hits.

All or nothing, now.

All That Glitters Is Not Gold, There's Brass And Copper Or It Might Be Plated!

 
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