Question

Draw the Lewis electron dot diagram for each element. a) strontium b) silicon

Short answer

Strontium: 2 dots; Silicon: 4 dots around the element symbols.

Step-by-step solution

Understand the Concept

Lewis electron dot diagrams represent the valence electrons of an atom. The number of dots around the symbol indicates the number of valence electrons.

Identify Valence Electrons for Strontium

Strontium is in Group 2 of the periodic table, which means it has 2 valence electrons.

Draw Lewis Dot Diagram for Strontium

Write the symbol 'Sr' for strontium. Then place two dots around the symbol, representing the two valence electrons. These dots can be on any side, but for simplicity, place one on the top and one on the bottom. This results in the drawing: Sr with two dots.

Identify Valence Electrons for Silicon

Silicon is in Group 14 of the periodic table, which means it has 4 valence electrons.

Draw Lewis Dot Diagram for Silicon

Write the symbol 'Si' for silicon. Place four dots around the symbol. These dots should be placed one on each side (top, bottom, left, right) to represent the four valence electrons.

Key concepts

Valence Electrons

Valence electrons are the electrons that reside in the outermost shell of an atom. They are crucial because they determine an element's chemical properties, including how it bonds with other elements. For example, the number of valence electrons can tell us whether an atom is likely to gain, lose, or share electrons to achieve a full outer shell, which is typically stable.

When drawing Lewis electron dot diagrams, we're interested solely in these outermost electrons since they participate in chemical bonding. Valence electrons are represented as dots around the chemical symbol of an element.

• Elements with similar valence electron counts will often exhibit similar chemical behaviors.
• The fewer the electrons needed to complete an outer shell, the more reactive the element typically is.
• The balance of valence electrons guides the formation of ionic or covalent bonds.

Understanding valence electrons helps predict and visualize how an element interacts in chemical reactions.

Periodic Table Groups

The periodic table is organized into vertical columns known as groups. Each group contains elements that share a common number of valence electrons, leading to similar chemical properties.

For example, elements in Group 1, known as the alkali metals, all have one valence electron. This single electron tends to be lost during reactions, making these elements highly reactive. On the other hand, elements in Group 18, the noble gases, have complete outer shells and, therefore, are typically unreactive.

• Group number often indicates the number of valence electrons for the main-group elements (Groups 1-2 and 13-18).
• Elements like sodium and potassium in Group 1 have similar reactivity because they have the same number of valence electrons.
• Understanding the group placement of an element aids in predicting its chemical behavior.

This organization by groups is a powerful tool for chemists, allowing them to infer a lot about an element's properties and behavior just from its position on the periodic table.

Chemical Symbol Representation

Chemical symbols are short notations derived from the Latin names of elements. They serve as the "shorthand" for representing elements in chemical reactions and diagrams. In the context of Lewis electron dot diagrams, each element is represented by its chemical symbol with dots around it showing the valence electrons.

When drawing, the dots are placed around the chemical symbol in a manner that reflects the number of valence electrons and, subsequently, their arrangement in bonds.

• Chemical symbols are always a capital letter or a capital letter followed by a lowercase letter, like 'H' for hydrogen or 'Na' for sodium.
• The notation is universally recognized, allowing scientists from around the world to communicate effectively despite language differences.
• In a Lewis structure, understanding where to place dots can help in predicting molecular shapes and bond formations.

Recognizing and accurately using chemical symbols is a foundational skill in chemistry, both for learning and communication.