Problem 7
Question
The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound. (A) HS (C) \(\mathrm{H}_{2} \mathrm{~S}\) (B) \(\mathrm{HS}_{2}\) (D) \(\mathrm{H}_{4} \mathrm{~S}\)
Step-by-Step Solution
Verified Answer
The molecular formula is \(\mathrm{H}_{2} \mathrm{S}\).
1Step 1: Determine Valence Electrons of Sulfur
Sulfur has an atomic number of 16, which means it has 16 electrons. Sulfur is in Group 16 of the periodic table and has 6 valence electrons.
2Step 2: Determine Valence Electrons of Hydrogen
Hydrogen is in Group 1 of the periodic table and has 1 valence electron.
3Step 3: Predict the Number of Bonds
Sulfur needs 2 more electrons to complete its octet (8 valence electrons). Each hydrogen atom can share 1 electron through covalent bonding. Therefore, sulfur will form 2 single covalent bonds with 2 hydrogen atoms.
4Step 4: Determine the Molecular Formula
Since one sulfur atom bonds with two hydrogen atoms, the molecular formula of hydrogen sulfide is \(\mathrm{H}_{2} \mathrm{S}\).
Key Concepts
Atomic StructureValence ElectronsCovalent Bonding
Atomic Structure
Atoms are the building blocks of matter, and understanding their structure is crucial in chemistry. Here’s a breakdown:
Atoms consist of three primary subatomic particles: protons, neutrons, and electrons. Protons are positively charged and found in the nucleus. Neutrons hold no charge and are also in the nucleus. Electrons, which are negatively charged, orbit around the nucleus in various energy levels or shells.
The atomic number of an element indicates the number of protons in its nucleus. For sulfur, the atomic number is 16, meaning it has 16 protons.
Protons and neutrons contribute most of the atomic mass. Electrons are much lighter and mainly determine an atom’s chemical properties through their arrangement around the nucleus.
Atoms consist of three primary subatomic particles: protons, neutrons, and electrons. Protons are positively charged and found in the nucleus. Neutrons hold no charge and are also in the nucleus. Electrons, which are negatively charged, orbit around the nucleus in various energy levels or shells.
The atomic number of an element indicates the number of protons in its nucleus. For sulfur, the atomic number is 16, meaning it has 16 protons.
Protons and neutrons contribute most of the atomic mass. Electrons are much lighter and mainly determine an atom’s chemical properties through their arrangement around the nucleus.
Valence Electrons
Valence electrons are the electrons in the outermost energy level of an atom. These electrons are important for chemical bonding. They determine how atoms interact with each other.
Sulfur, with an atomic number of 16, has its electrons arranged in shells: 2 in the first shell, 8 in the second, and 6 in the outermost (third) shell. These 6 outer electrons are sulfur's valence electrons.
Hydrogen, with an atomic number of 1, has only 1 electron, which is its valence electron because it is the only one in the first shell.
Understanding the number of valence electrons helps predict how atoms will bond to form molecules. Elements tend to bond in ways that fill their outer shells, achieving a more stable electron configuration, similar to noble gases.
Sulfur, with an atomic number of 16, has its electrons arranged in shells: 2 in the first shell, 8 in the second, and 6 in the outermost (third) shell. These 6 outer electrons are sulfur's valence electrons.
Hydrogen, with an atomic number of 1, has only 1 electron, which is its valence electron because it is the only one in the first shell.
Understanding the number of valence electrons helps predict how atoms will bond to form molecules. Elements tend to bond in ways that fill their outer shells, achieving a more stable electron configuration, similar to noble gases.
Covalent Bonding
Covalent bonding is a type of chemical bond formed when atoms share electrons. This type of bond usually occurs between nonmetals and is essential for building complex molecules.
In a covalent bond, each atom shares one or more of its valence electrons with another atom. This mutual sharing helps both atoms achieve a stable electron configuration.
For example, sulfur has 6 valence electrons and needs 2 more to complete its outer shell. Hydrogen has 1 valence electron and needs one more to fill its first shell. To achieve stability, sulfur shares one electron with each of 2 hydrogen atoms, forming 2 single covalent bonds. This sharing results in the molecular formula for hydrogen sulfide: \( \mathrm{H}_{2} \mathrm{S} \). Thus, both hydrogen and sulfur achieve full outer electron shells through this bonding mechanism.
In a covalent bond, each atom shares one or more of its valence electrons with another atom. This mutual sharing helps both atoms achieve a stable electron configuration.
For example, sulfur has 6 valence electrons and needs 2 more to complete its outer shell. Hydrogen has 1 valence electron and needs one more to fill its first shell. To achieve stability, sulfur shares one electron with each of 2 hydrogen atoms, forming 2 single covalent bonds. This sharing results in the molecular formula for hydrogen sulfide: \( \mathrm{H}_{2} \mathrm{S} \). Thus, both hydrogen and sulfur achieve full outer electron shells through this bonding mechanism.
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