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Lewis Structure of Group 6A Central Atoms

General Chemistry • Chemical Bonds

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Group 16 (6A) Central Atoms – Two Bonds + Two Lone Pairs (AX2E2)

Choose a molecule with a Group 16 central atom and inspect how 2 bonding pairs and 2 lone pairs produce the classic AX2E2 bent geometry.

This calculator counts valence electrons, shows the Lewis-structure logic step by step, and draws interactive diagrams that make lone-pair placement, bent geometry, and electron domains easier to understand.

Direct paste is supported. The calculator can read entries copied from a CSV or spreadsheet if the cells contain supported formulas such as H2O, OF2, SCl2, or OCl2.

Group 16 central atoms usually have 4 electron domains: 2 bonding pairs and 2 lone pairs. VSEPR describes this as AX2E2, which gives a tetrahedral electron-domain geometry but a bent molecular shape.

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Frequently Asked Questions

What does AX2E2 mean for a Group 16 central atom?

AX2E2 means the central atom has two bonded atoms (X2) and two lone pairs (E2). This gives four electron domains and typically leads to a bent molecular shape.

How do you count total valence electrons for H2O or OF2?

Add the valence electrons from each atom. Oxygen contributes 6, each hydrogen contributes 1, and each fluorine contributes 7, so H2O has 6 + 2x1 = 8 and OF2 has 6 + 2x7 = 20 total valence electrons.

Why is the shape bent for molecules like H2O and SCl2?

The central atom has two bonding pairs and two lone pairs, so lone-pair repulsions push the bonded atoms closer together. Even though the electron domains are arranged tetrahedrally, the visible molecular shape is bent.

What is the difference between electron-domain geometry and molecular shape for AX2E2?

Electron-domain geometry counts both bonds and lone pairs, so AX2E2 has a tetrahedral electron-domain arrangement. Molecular shape ignores lone pairs, so with two bonded atoms the shape is bent.

How many lone pairs are on the central Group 16 atom in these examples?

For the molecules in this tool, the central Group 16 atom has two lone pairs. The remaining valence electrons after forming two single bonds are placed as two nonbonding pairs on the central atom.

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