Question

Arrange the following in order of increasing mass. (a) a sodium ion (b) a selenium atom (c) a sulfur \(\left(\mathrm{S}_{8}\right)\) molecule (d) a scandium atom

Short answer

Question: Arrange the following substances in order of increasing mass: sodium ion (Na+), selenium atom (Se), sulfur molecule (S8), and scandium atom (Sc). Answer: The correct order is sodium ion (Na+), scandium atom (Sc), selenium atom (Se), and sulfur molecule (S8).

Step-by-step solution

Find the atomic mass of each element

Consult the periodic table to find the atomic mass of each element involved in this exercise: - Sodium (Na): 22.99 g/mol - Selenium (Se): 78.96 g/mol - Sulfur (S): 32.07 g/mol - Scandium (Sc): 44.96 g/mol

Calculate the mass of the sodium ion

A sodium ion (Na+) has lost one electron compared to a neutral sodium atom, but the loss of an electron does not significantly affect its mass. So, the mass of a sodium ion is approximately the same as the atomic mass of sodium: - Mass of sodium ion (Na+): 22.99 g/mol

Calculate the mass of the sulfur molecule

A sulfur molecule (S8) consists of eight sulfur atoms bonded together. To find the mass of one sulfur molecule, multiply the atomic mass of sulfur by the number of atoms in the molecule: - Mass of sulfur molecule (S8): 8 × 32.07 g/mol = 256.56 g/mol

Arrange the substances in order of increasing mass

Now that we have the masses of all four substances, we can arrange them in order of increasing mass: 1. Sodium ion (Na+): 22.99 g/mol 2. Scandium atom (Sc): 44.96 g/mol 3. Selenium atom (Se): 78.96 g/mol 4. Sulfur molecule (S8): 256.56 g/mol So, the correct order of increasing mass is: (a) sodium ion, (d) scandium atom, (b) selenium atom, (c) sulfur molecule.

Key concepts

Understanding the Periodic Table

The periodic table is a comprehensive chart that organizes chemical elements according to their atomic numbers, electron configurations, and recurring chemical properties. It's essentially a map of the basic building blocks of matter. The elements are arranged in rows called periods and columns known as groups or families. The atomic number increases from left to right and from top to bottom.
Each element in the periodic table is represented by a unique symbol and provides essential information such as atomic mass, which is crucial in solving problems involving the comparison of masses, like the exercise mentioned. The atomic mass is usually displayed underneath the symbol of each element and is measured in atomic mass units (amu) or grams/mol. This facilitates calculating the mass of atoms, ions, and molecules, as showcased in the exercise where atomic masses from the periodic table are used to determine the order of increasing mass for various species.

Calculating Molecular Mass

Molecular mass, also known as molecular weight, is the sum of the atomic masses of all atoms in a molecule. It's measured in atomic mass units (amu) or grams/mol, corresponding to the mass of one mole of the substance.
To calculate the molecular mass, as in the exercise with the sulfur molecule (S8), one must multiply the atomic mass of a single atom (found on the periodic table) by the number of atoms in the molecule. The result is the mass of the molecule as a whole, a fundamental concept in chemistry when dealing with stoichiometry and reactions. In the aforementioned exercise, multiplying the atomic mass of sulfur by eight yields the molecular mass of an S8 molecule. Understanding molecular mass calculation is essential for interpreting the composition and reactions of molecular substances.

Chemical Elements and Their Properties

Chemical elements are substances that consist of only one type of atom and cannot be broken down into simpler substances by chemical means. Each element has its own set of properties, including atomic mass, electron configuration, and chemical reactivity.
In the exercise context, these properties help to understand and compare different elements and their ions or molecules. For example, the mass of a sodium atom remains nearly the same as that of a sodium ion because losing or gaining electrons does not significantly change an atom's mass. This subtle yet important distinction is why the mass of the sodium ion is still taken as the atomic mass of sodium from the periodic table. It's also why recognizing and comparing the properties of chemical elements is critical when determining the order of increasing mass or engaging in chemical analysis and synthesis.