Scientific Understanding

**What sections should I know before attempting to learn this section?**

—> Complete Electron Configuration **Part 3**

**What are quantum numbers?**

**VIDEO Explanation of quantum numbers.**

Quantum numbers and electron configurations are talking about the same thing. Each of them represent where the electrons are around the atom. However, the quantum numbers do it in a different way than the electron configurations do. The first difference is the quantum numbers only talk about one electron at a time. The quantum numbers also divide into 4 different categories represented by letters. Those categories are n, L, m_{L}, m_{s}.

The quantum category n stands for the energy level. This is the same energy level that was discussed in the earlier energy level section of this lesson. This periodic table link can help you recognize the energy levels on the periodic table.

**Examples**: Give the n (energy level) of the last electron in each element.

Be | n = 2 |

Pd | n = 4 |

Al | n = 3 |

**PRACTICE PROBLEMS**: Give the n (energy level) of the last electron in each element.

He | n = 1 |

Fe | n = 3 |

Br | n = 4 |

Na | n = 3 |

U | n = 5 |

Hg | n = 5 |