Question

What simple ion does each of the following elements most commonly form? a. sodium b. iodine c. potassium d. calcium e. sulfur f. magnesium g. aluminum h. nitrogen

Short answer

The most common simple ions formed by each element are: a. Sodium: $N{a}^{+}$ b. Iodine: $I^{-}$ c. Potassium: $K^{+}$ d. Calcium: $C{a}^{2+}$ e. Sulfur: $S^{2-}$ f. Magnesium: $M{g}^{2+}$ g. Aluminum: $A{l}^{3+}$ h. Nitrogen: $N^{3-}$ (although covalent compounds are more common)

Step-by-step solution

a. Sodium (Na)

Sodium (Na) belongs to group 1 (alkali metals) of the periodic table. Elements in group 1 typically form ions with a +1 charge by losing one electron. So, the most common simple ion formed by sodium is $N{a}^{+}$.

b. Iodine (I)

Iodine (I) belongs to group 17 (halogens) of the periodic table. Elements in group 17 typically form ions with a -1 charge by gaining one electron. So, the most common simple ion formed by iodine is $I^{-}$.

c. Potassium (K)

Potassium (K) belongs to group 1 (alkali metals) of the periodic table, just like sodium. So, the most common simple ion formed by potassium is $K^{+}$.

d. Calcium (Ca)

Calcium (Ca) belongs to group 2 (alkaline earth metals) of the periodic table. Elements in group 2 typically form ions with a +2 charge by losing two electrons. So, the most common simple ion formed by calcium is $C{a}^{2+}$.

e. Sulfur (S)

Sulfur (S) belongs to group 16 (chalcogens) of the periodic table. Elements in group 16 typically form ions with a -2 charge by gaining two electrons. So, the most common simple ion formed by sulfur is $S^{2-}$.

f. Magnesium (Mg)

Magnesium (Mg) belongs to group 2 (alkaline earth metals) of the periodic table, just like calcium. So, the most common simple ion formed by magnesium is $M{g}^{2+}$.

g. Aluminum (Al)

Aluminum (Al) belongs to group 13 of the periodic table. Elements in group 13 typically form ions with a +3 charge by losing three electrons. So, the most common simple ion formed by aluminum is $A{l}^{3+}$.

h. Nitrogen (N)

Nitrogen (N) belongs to group 15 (pnictogens) of the periodic table. Elements in group 15 typically form ions with a -3 charge by gaining three electrons. However, nitrogen is more likely to form compounds through covalent bonds rather than ionic bonds. Nevertheless, the most common simple ion is $N^{3-}$, although it is not as prevalent as covalent compounds like ammonia (NH3) or nitrogen oxide (NO).

Key concepts

Periodic Table Groups

Understanding the periodic table is fundamental in chemistry, as it categorizes elements based on shared properties and reactivity. The groups, or columns, organize elements by the number of valence electrons which directly correlates with their ability to form ions.

For instance, Group 1 contains the alkali metals like sodium (Na) and potassium (K), which have a single valence electron they readily lose to form +1 ions such as $N{a}^{+}$ and $K^{+}$. Similarly, Group 17 elements, known as halogens, such as iodine (I), have seven valence electrons, and they tend to gain one electron to attain a stable octet, forming ions like $I^{-}$.

The exercise improvement advice suggests highlighting these patterns and explaining how understanding the group norms can help in predicting the common ions formed.

Ion Formation

Ion formation is a key concept in understanding chemical reactions and bonding. Atoms form ions to reach a stable electronic configuration, often modeled by the 'octet rule', where an atom tends to have eight electrons in its outermost shell.

Metals, located on the left side of the periodic table, typically form positive ions, or cations, by losing electrons. For example, calcium (Ca) from Group 2 loses two electrons to form a $C{a}^{2+}$ ion. Nonmetals, on the right side, tend to form negative ions, or anions, by gaining electrons, like sulfur (S) from Group 16 gaining two electrons to end up as $S^{2-}$.

Incorporating why atoms form ions—usually to attain a noble gas electron configuration—and emphasizing the predictability of ion charges based on group trends can greatly aid in understanding.

Chemical Bonding

Chemical bonding is the force that holds atoms together in compounds. The type of bond formed often depends on the properties of the involved elements, such as their position on the periodic table and their electronegativity.

There are several types of chemical bonds, with ionic and covalent bonds being primary. Ionic bonding occurs when there's a complete transfer of electrons from one atom to another, typically between metals and nonmetals. Magnesium (Mg) and aluminum (Al), for example, form ionic compounds by transferring their valence electrons to nonmetals.

In contrast, covalent bonding involves the sharing of electrons between atoms and is common among nonmetals, like the bonds seen in nitrogen compounds such as ammonia (NH3). Highlighting the nature of ionic and covalent bonds, and how elements like nitrogen (N) prefer covalent bonding, can provide clarity to students grappling with the concept of bonding.