Diagramming Atoms Labeling Electrons – Part 1 Supplement to Book – Glencoe: Chapter 22 and 19-3

Electron shell diagrams Electron shell diagrams are ways to visualize the arrangement of electrons in an atom These diagrams show which energy levels, called shells, the electrons are found.

Electron shell diagrams Particle locations 1. Nucleus All protons (p+) are found in the nucleus All neutrons (N)

Electron shell diagrams 2. Electron Cloud - All electrons (e-) are found in the electron clouds in orbitals

Electron shell diagrams 3. Neutral atoms of any element have equal numbers of protons and electrons 4. The number of neutrons can be found from the atomic mass of an element - Round atomic mass to the nearest whole number  mass number - Mass number = Atomic number + neutron number

Energy levels in atoms 1. Electrons are modeled in atoms combining two atomic models - Bohr’s model – electrons orbit the nucleus in fixed paths - The modern atomic model – electrons are found in areas called electron clouds

Energy levels in atoms 2. There are distinct energy levels in an atom  “n” number a. “n” can equal 1, 2, 3, 4, 5, 6, or 7 b. Only whole, n = 1 non-negative numbers n = 2 n = 3

Energy levels in atoms 3. Energy level numbers generally correspond to period number (there is a pattern to it)

Energy levels in atoms 4. Each energy level may contain only a specific maximum number of electrons n # 1 2 3 4 5 6 7 Max e- 8 18 32

Energy levels in atoms Energy levels fill up in a specific order to  lowest energy (n = 1) to highest energy (n = 7)