atoms - choose a jigsaw puzzle to solve

An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element. Every solid, liquid , gas, and plasma is composed of neutral or ionized atoms. Atoms are extremely small; typical sizes are around 100 picometers (1×10−10 m, a ten-millionth of a millimeter , or 1/254,000,000 of an inch). They are so small that accurately predicting their behavior using classical physics – as if they were billiard balls, for example – is not possible. This due to quantum effects. Current atomic models now use quantum principles to better explain and predict this behavior . Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. Protons and neutrons are called nucleons.