Charge of ions

Understanding Charge of Ions

  • Definition of Ion: An ion is defined as an atom or molecule that has a net electrical charge due to the loss or gain of one or more electrons.

Example 1: Charge of a Calcium Ion with 18 Electrons

  • Initial Data Provided:

    • Calcium ion has 18 electrons.

  • Tip for Calculation:

    • Use a periodic table to determine the properties of calcium.

Determining the Charge of Calcium Ion

  • Atomic Number of Calcium:

    • Calcium has an atomic number of 20.

    • Protons Count:

    • Number of protons = 20 (provides positive charge).

  • Electrons Count:

    • Number of electrons = 18 (provides negative charge).

Net Charge Calculation

  • Formula to Find Net Charge:

    • Net Charge = Number of Protons - Number of Electrons

  • Calculation:

    • Net Charge = 20 (protons) - 18 (electrons) = 2

    • Denote this as a charge of +2 or calcium 2 plus (Ca²⁺)

Background Context

  • Neutral Calcium Atom:

    • A neutral calcium atom would have equal numbers of protons and electrons (20 each).

    • When calcium loses 2 electrons, it becomes a calcium ion with a positive 2 charge, indicating it has more protons than electrons.

Example 2: Charge of an Ion with 7 Protons, 8 Neutrons, and 10 Electrons

  • Initial Data Provided:

    • Ion has 7 protons, 8 neutrons, and 10 electrons.

Determining the Charge

  • Proton Count:

    • Number of protons = 7 (providing positive charge).

  • Electron Count:

    • Number of electrons = 10 (providing negative charge).

  • Charge Calculation:

    • Net Charge = Number of Protons - Number of Electrons

    • Calculation:

    • Net Charge = 7 (protons) - 10 (electrons) = -3

    • Denote this as a charge of -3 or three minus (3⁻).

Identifying the Ion

  • Element Determination:

    • The element with 7 protons is nitrogen (N) which leads to the conclusion that this ion is a nitrogen ion, denoted as N³⁻.

Recap

  • Key Takeaways:

    • The charge of an ion can be determined by subtracting the number of electrons from the number of protons.

    • A positive charge indicates a loss of electrons, while a negative charge indicates a gain of electrons.

    • Use the periodic table to identify elements based on the number of protons.

  • Formulas to Remember:

    • For any ion:

    • Net Charge = Protons - Electrons