Selenium tetrabromide (SeBr4) is primarily used as a brominating agent in specialized chemical synthesis. Here is its lewis structure and steps to draw it.

Step 1: Calculate total valence electrons

Se (Selenium, Group VIA): 6

Br (Bromine, Group VIIA): 7 × 4 = 28

Total valence electrons: 6 + 28 = 34 e?

Step 2: Determine the central atom

Se has lower electronegativity than Br; as a Period 4 element, it possesses empty d-orbitals and can accommodate an expanded octet, making it the central atom.

Skeleton: 4 Se–Br single bonds.

Step 3: Construct the σ-bond framework

4 single bonds; bonding electrons: 4 × 2 = 8 e?

Remaining electrons: 34 ? 8 = 26 e?

Step 4: Fill lone pairs on peripheral Br atoms

Each Br is connected by a single bond and requires 3 lone pairs (6 e?) to satisfy the octet rule.

Total electrons for Br lone pairs: 4 × 6 = 24 e?

Remaining electrons after allocation: 26 ? 24 = 2 e?

Step 5: Place remaining electrons on the central Se atom

2 e? = 1 lone pair located on the Se atom.

Verification of total electrons

Bonding electrons (8) + Br lone pairs (24) + Se lone pair (2) = 34 e?

Expanded octet check

Se: 4 single bonds (8 bonding electrons) + 1 lone pair (2 e?) = 10 electrons; expanded octets are permissible for Period 4 elements.