IB MYP Integrated Science- Chemistry- Electron configuration-Study Notes - New Syllabus

Electron Configuration

Electron configuration describes how electrons are arranged in energy levels (shells) around the nucleus of an atom. This arrangement determines the chemical properties and reactivity of an element.

Energy Levels (Shells)

Electrons occupy specific energy levels around the nucleus. These are sometimes called shells.

• First shell: maximum 2 electrons
• Second shell: maximum 8 electrons
• Third shell: maximum 8 electrons (for MYP level)

Filling Order (Electron Arrangement Rules)

Electrons fill energy levels starting from the lowest energy level first before moving to higher ones.

Key rules:

• Electrons fill the lowest energy level available first
• Each shell has a maximum capacity
• Outer shells determine chemical behavior

Writing Electron Configuration

Electron configuration is written as numbers showing how many electrons are in each shell.

Examples:

• Helium (2): \( 2 \)
• Carbon (6): \( 2,4 \)
• Neon (10): \( 2,8 \)
• Magnesium (12): \( 2,8,2 \)

Valence Electrons and Stability

The outermost electrons are called valence electrons. Atoms tend to become more stable when their outer shell is full.

A full outer shell (usually 8 electrons) is called a stable electron configuration (noble gas configuration).

Formation of Ions (Link to Electron Configuration)

Atoms can gain or lose electrons to achieve a full outer shell.

• Metals tend to lose electrons → form positive ions
• Non-metals tend to gain electrons → form negative ions

Example:

\( \mathrm{Na: 2,8,1 \rightarrow Na^+: 2,8} \)

\( \mathrm{Cl: 2,8,7 \rightarrow Cl^-: 2,8,8} \)

Bohr Diagrams

Electron configuration can be represented visually using Bohr diagrams, where electrons are shown in circular shells around the nucleus.

Real-World Importance

Electron configuration explains why elements react, form bonds, and create compounds essential for life.