An echocardiogram uses sound waves to produce images of your heart. This commonly used test allows your doctor to see your heart beating and pumping blood. Your doctor can use the images from an echocardiogram to identify heart disease.Depending on what information your doctor needs, you may have one of several types of echocardiograms.his commonly used test allows your doctor to see your heart beating and pumping blood. Your doctor can use the images from an echocardiogram to identify heart disease. Depending on what information your doctor needs, you may have one of several types of echocardiograms.
The octet rule is a chemical rule of thumb that reflects observation that atoms of main-group elements tend to combine in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.he octet rule is a chemical rule of thumb that reflects observation that atoms of main-group elements tend to combine in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.
Valence electrons are the electrons usually involved in a chemical reaction. Electron dot structures are diagrams that show valence electrons in the atoms of an element as dots. The octet rule states that in forming compounds, atoms tend to achieve the electron configuration of a noble gas. an octet is a set of eight.