Question

Draw a Lewis electron-dot symbol for each: (a) Sr (b) \(P\) (c) S

Short answer

The Lewis symbols are: Sr with 2 dots, P with 5 dots, S with 6 dots.

Step-by-step solution

Understanding Lewis Electron-Dot Symbols

Lewis electron-dot symbols represent the valence electrons of an atom as dots around the element symbol. First, identify the number of valence electrons for each element.

Determine Valence Electrons for Sr

Strontium (Sr) is in Group 2 of the periodic table, so it has 2 valence electrons. Draw the Sr symbol and place one dot on each of the four sides until all valence electrons are represented.

Draw the Lewis Symbol for Sr

Since Sr has 2 valence electrons, place two dots around the symbol Sr. The final diagram is \[Sr \bigodot \bigodot\].

Determine Valence Electrons for P

Phosphorus (P) is in Group 15 of the periodic table, so it has 5 valence electrons. Draw the P symbol and place dots around it to represent its 5 valence electrons.

Draw the Lewis Symbol for P

Arrange 5 dots around the symbol P, with single dots occupying each side first, then pairing up remaining dots. The final diagram is \[\mathbf{P} \bigodot \bigodot \bigodot \bigodot \bigodot\].

Determine Valence Electrons for S

Sulfur (S) is in Group 16 of the periodic table, so it has 6 valence electrons. Draw the S symbol and add dots to represent these electrons.

Draw the Lewis Symbol for S

Place 6 dots around the symbol S, with single dots on each side first, then pairing up the remaining dots. The final diagram is \[\mathbf{S} \bigodot \bigodot \bigodot \bigodot \bigodot \bigodot\].

Key concepts

Valence Electrons

Valence electrons are the electrons found in the outermost shell of an atom. These electrons are important because they are involved in chemical bonding and reactions. To find the number of valence electrons, look at the group number on the periodic table. For example, for elements in Group 2 like Strontium (Sr), there are 2 valence electrons. Similarly, for elements in Group 15 like Phosphorus (P), there are 5 valence electrons, and for Group 16 like Sulfur (S), there are 6 valence electrons. Knowing the number of valence electrons allows us to draw Lewis electron-dot symbols, which help in visualizing the molecule's bonding.

Periodic Table Groups

The periodic table is divided into groups (columns) and periods (rows). Periodic table groups help us determine the number of valence electrons in an element.

For instance:

• Group 1 elements (like sodium) have 1 valence electron.
• Group 2 elements (like strontium) have 2 valence electrons.
• Group 15 elements (like phosphorus) have 5 valence electrons.
• Group 16 elements (like sulfur) have 6 valence electrons.

By identifying the group of an element, you instantly know how many valence electrons it has, which is crucial for drawing Lewis electron-dot symbols and understanding how the element will interact chemically.

Electron Configuration

Electron configuration shows the distribution of electrons around an atom's nucleus. The configuration describes which orbitals the electrons occupy. For instance, the electron configuration for phosphorus (P, atomic number 15) is 1s² 2s² 2p⁶ 3s² 3p³. This indicates there are 2 electrons in the 1s orbital, 2 in the 2s orbital, 6 in the 2p orbital, 2 in the 3s orbital, and 3 in the 3p orbital.

The electrons in the highest energy level (or outer shell) are the valence electrons. For phosphorus, there are 5 valence electrons (from the 3s and 3p orbitals). These outermost electrons are represented in Lewis electron-dot symbols.

Understanding electron configuration is important because it helps us predict how an atom can bond and interact with other atoms.