The Lewis structure for SrBr2, or strontium bromide, can be drawn by following a series of steps that reflect the bonding between strontium (Sr) and bromine (Br) atoms. To create the Lewis structure, we must first determine the total number of valence electrons available for the molecule.
Strontium, being in Group 2 of the periodic table, has two valence electrons, while bromine, in Group 17, has seven valence electrons. Since we have one strontium atom and two bromine atoms in SrBr2, we calculate the total valence electrons as follows:
- Strontium (Sr) contributes 2 valence electrons.
- Each bromine (Br) contributes 7 valence electrons, so two bromine atoms contribute 14 valence electrons.
Therefore, the total number of valence electrons in SrBr2 is 2 (from Sr) + 14 (from two Br atoms) = 16 valence electrons.
To draw the Lewis structure: 1. Place the atoms relative to each other: In this case, the strontium atom will be the central atom because it can form more than one bond, and the bromine atoms will be surrounding it.
Determine the bonds: Strontium needs to lose two electrons to achieve a noble gas configuration, which it does by forming two single bonds with the bromine atoms. Each bromine atom shares one pair of electrons with strontium, thus achieving a noble gas configuration for each bromine atom as well.
Distribute the remaining electrons: After forming two single bonds between strontium and the two bromine atoms, we have used 4 electrons (2 for each bond). This leaves us with 16 - 4 = 12 electrons to distribute.
Satisfy the octet rule for each atom: Each bromine atom already has one bond (2 electrons) with strontium and needs 6 more electrons to satisfy the octet rule. We distribute the remaining 12 electrons around the bromine atoms to satisfy their octet rule, which means each bromine atom will have 3 lone pairs (6 electrons).
The resulting Lewis structure for SrBr2 shows the strontium atom bonded to two bromine atoms with single bonds, and each bromine atom has three lone pairs of electrons. This structure satisfies the octet rule for the bromine atoms and reflects the ionic character of the Sr-Br bonds, as strontium tends to lose electrons to form a +2 ion, and bromine tends to gain electrons to form a -1 ion, although in Lewis structures, we primarily focus on the covalent representation.
In reality, SrBr2 is more accurately described as an ionic compound due to the significant difference in electronegativity between strontium and bromine, leading to the formation of Sr²⁺ and Br⁻ ions rather than a covalent bond. However, the Lewis structure provides a simplified model to understand the basic bonding arrangement.
Remember, the Lewis structure is a simplification and does not fully capture the complexity of the molecular orbital structure or the true nature of the bonding in the molecule, especially in cases where ionic bonding is predominant.
