diff --git a/Electronics/Physics_of_electricity/Electrons.md b/Electronics/Physics_of_electricity/Electrons.md
index 36f7761..9c112c4 100644
--- a/Electronics/Physics_of_electricity/Electrons.md
+++ b/Electronics/Physics_of_electricity/Electrons.md
@@ -4,4 +4,13 @@ categories:
 tags: [physics]
 ---
 
-# Electrons
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+# Electrons
+
+## Shells
+
+Electrons orbit in concentric circuits around the nucleus of the atom. Each orbit is called a **shell**. 
+
+Each shell can accomodate a maximum number of electrons. The shells are designated letters and filled in sequence moving out from the shell nearest to the nucleus. 
+
+![](/img/electron-shells.svg.svg)
+b
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