Electron Configuration and Valence Electrons. The electrons in an atom fill up its atomic orbitals according to the Aufbau Principle; Aufbau, in German, means building up..ach element has a number of valence electrons equal to its group number on the Periodic Table. This table illustrates a number of interesting, and complicating, features of electron configuration. Figure %: The periodicity of valence electrons. First, as electrons become higher in energy, a shift takes place.
I took the pregnancy test early at 2 & 3 weeks pregnant, and it came up negative twice. Yet I could feel something was different about my body, even though I had my cycle it fell short a few days, and was very light. Afterwards, I had breast tenderness, and dizziness.
A negative result can mean that you are not pregnant, you took the test too early, or you took the test wrong. Pregnancy tests vary in their sensitivity (how soon they can detect the hormone hCG), and you may not have given your body enough time to produce enough hCG hormones that will show up on the test. Also, if you let a test sit for too long (after the instructions on the box tell you), the test is invalid.