Lesson Worksheet: Electronic Configurations Science

In this worksheet, we will practice writing electronic configurations for atoms or ions and identifying an atom from its electronic configuration.


An atom of boron has 5 electrons. How many electrons does this atom have in its outer level?


The atomic numbers of a selection of elements are shown in the table below. How many more electrons does an atom of beryllium need to gain to obtain a full outer level?

Atomic Number456789


An atom of nitrogen has an atomic number of 7. An ion of nitrogen has an extra 3 electrons. What is the electronic configuration of the ion?

  • A2, 5
  • B2, 9
  • C8, 3
  • D2, 8
  • E5, 5


In total, how many electrons are needed for both the K and L energy levels to be full?


In general, how many electrons are in the outer level of an atom of an inert gas such as neon?

  • A8
  • B10
  • C12
  • D6
  • E4


An atom contains 5 electrons. How many of these electrons occupy the L energy level?


A magnesium ion contains two fewer electrons than an atom of magnesium. If the atomic number of magnesium is 12, which of the following energy level diagrams shows the correct electronic configuration of the magnesium ion?

  • A
  • B
  • C
  • D
  • E


An atom of oxygen has 8 protons in its nucleus. Which energy level diagram shows the correct electronic configuration for oxygen?

  • A
  • B
  • C
  • D
  • E


Which of the following energy level diagrams corresponds to the least reactive atom?

  • A
  • B
  • C
  • D
  • E


A general energy level diagram for an atom is shown below. What is the maximum number of electrons that can occupy the K energy level?

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