Electronic structure: 288 rule

Electronic structure: 288 rule

Lessons

In this lesson, we will learn:
• A method to determine electronic structure in atoms.
• The reason electronic structure is important to understanding chemical elements.
• How to predict the number of outer shell electrons in elements.

Notes:

• Electrons in atoms exist outside the nucleus in energy levels sometimes known as shells. The number of electrons in an atom's outer electron shell is called the electron shell configuration.

• The reactivity of an element is strongly linked to the number of outer shell electrons an atom of the element has. Elements react in ways to obtain a full outer shell, whether by sharing, losing or gaining electrons (see our videos on bonding and types of compounds).

• The 1st, 2nd, and 3rd shells can hold 2, 8 and 8 electrons respectively. Once a shell is filled up, any further electrons must fill in a new higher level shell.

• The number of outer shell electrons is a defining factor of how the periodic table is laid out: elements in the same group have the same outer shell electron configuration.

  • Introduction
    Introduction to electronic structure
    a)
    Analysing the structure of the atom.

    b)
    The 2-8-8 Rule: Walkthrough

    c)
    A shortcut to the periodic table: predicting electron shells

  • 1.
    Apply your knowledge of electron shells to find the electron configuration of elements.
    Give the electronic structure for an atom of the following chemical elements:
    a)
    i) B
    ii) Si

    b)
    i) Mg
    ii) Ar
    iii) F

  • 2.
    Use the electron configuration to identify elements of the Periodic Table.
    Which chemical element would display this electron shell configuration?
    a)
    i) (2,2)
    ii) (2,7)

    b)
    i) (2,8,1)
    ii) (2,8,7)

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2.
Atomic Structure
2.1
Atomic structure
2.2
Electronic structure: 288 rule
2.3
Electronic structure: Subshells
2.4
Ion formation
IB Chemistry