Valence Electron and Core Electrons

Valence Electrons and Electron Configuration

• Transition metals typically have a varying number of valence electrons.
• Boron (B) is an element that has three valence electrons.

Octet Rule and Stability

• Atoms or ions are considered most stable when they have a full outer energy level, or octet, according to the octet rule.

Elements and Valence Shells

• Hydrogen (H) is an element that does not start with a full valence shell.

Bond Formation and Valence Electrons

• Carbon (C) typically forms four bonds due to its valence electron configuration.
• Valence electrons are responsible for forming bonds between atoms.

Core Electrons and Electron Configuration

• Core electrons are the other electrons in an atom besides valence electrons.
• Sodium (Na) has one valence electron.
• In the electron configuration for carbon (C), there are two core electrons.

Counting Valence Electrons in the Periodic Table

• The number of valence electrons for Group A elements in the periodic table can be counted by looking at the group number.

Element Valence Electrons

• A fluorine (F) atom has seven valence electrons.

Lewis Structures

• In the Lewis structure of arsenic trifluoride, arsenic is the central atom because it is less electronegative than fluorine.
• In the Lewis structure of methane, carbon is the central atom because it is less electronegative than hydrogen.
• Nitrogen gas (N2) has a triple bond between the two nitrogen atoms because it allows each nitrogen atom to achieve a full octet.
• There are three lone pairs on each nitrogen atom in nitrogen gas.

Learn about valence electrons, which play a crucial role in determining the chemical reactivity of elements, and core electrons that are not involved in chemical bonding. Explore how to identify valence electrons in an atom's electron configuration.