Consider an ion with the symbol Y^3- formed from a representative element.
c. If Y is in Period 3, what is the element?

Verified step by step guidance

1. Identify the charge of the ion, which is 3⁻. This indicates that the element has gained 3 electrons to form the ion.
2. Determine the number of valence electrons in the neutral atom of the element. Since the ion has gained 3 electrons, the neutral atom must have had 5 valence electrons to reach a full octet (8 valence electrons).
3. Locate the group in the periodic table that corresponds to 5 valence electrons. Elements with 5 valence electrons are in Group 15 (or Group 5A in older notation).
4. Focus on Period 3 of the periodic table, as the problem specifies that the element is in Period 3. The element in Group 15 and Period 3 is phosphorus (P).
5. Conclude that the element Y is phosphorus (P), and the ion Y³⁻ corresponds to the phosphide ion (P³⁻).

Key Concepts

Ion Formation

Ions are charged particles that form when atoms gain or lose electrons. A cation has a positive charge due to the loss of electrons, while an anion has a negative charge from gaining electrons. In this case, Y³⁻ indicates that the element has gained three electrons, resulting in a negative charge.

Periodic Table and Periods

The periodic table organizes elements based on their atomic number and properties. Each horizontal row is called a period, and elements in the same period share similar energy levels. Period 3 includes elements such as sodium, magnesium, and sulfur, which are crucial for identifying the element Y.

Representative Elements

Representative elements, also known as main group elements, are found in groups 1, 2, and 13-18 of the periodic table. They exhibit a wide range of chemical and physical properties and typically form predictable ions. Understanding that Y is a representative element helps narrow down the possibilities for its identity in Period 3.