How many electrons does an atom of each of the following elements need to gain to achieve a noble gas configuration? By gaining that many electrons, which noble gas configuration is achieved?
(c) Phosphorus

Verified step by step guidance

1. Step 1: Understand the concept of noble gas configuration. Noble gases have a full valence shell, which is typically 8 electrons (except for helium, which has 2). Atoms of other elements tend to gain, lose, or share electrons to achieve this stable configuration.
2. Step 2: Determine the electron configuration of phosphorus (P). Phosphorus has an atomic number of 15, meaning it has 15 electrons. Its electron configuration is: ${\mathrm{1s}}^2{\mathrm{2s}}^2{\mathrm{2p}}^6{\mathrm{3s}}^2{\mathrm{3p}}^3.$
3. Step 3: Identify the nearest noble gas. The nearest noble gas after phosphorus is argon (Ar), which has an atomic number of 18 and an electron configuration of: ${\mathrm{1s}}^2{\mathrm{2s}}^2{\mathrm{2p}}^6{\mathrm{3s}}^2{\mathrm{3p}}^6.$
4. Step 4: Determine how many electrons phosphorus needs to gain to achieve the electron configuration of argon. Phosphorus currently has 3 electrons in its 3p orbital, and it needs 3 more electrons to fill the 3p orbital completely (to reach 3p$6$).
5. Step 5: Conclude that phosphorus needs to gain 3 electrons to achieve the noble gas configuration of argon.

Key Concepts

Noble Gas Configuration

Noble gas configuration refers to the electron arrangement of noble gases, which have full outer electron shells, making them stable and unreactive. Atoms tend to gain, lose, or share electrons to achieve this stable configuration, typically resembling the nearest noble gas in the periodic table.

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom that are involved in chemical bonding. The number of valence electrons determines how an element interacts with others and how many electrons it needs to gain or lose to achieve a stable electron configuration.

Electron Affinity

Electron affinity is the energy change that occurs when an atom gains an electron. Elements with high electron affinity tend to gain electrons more readily, which is crucial for understanding how many electrons an atom like phosphorus needs to gain to achieve a noble gas configuration.