Problem 64
Question
Complete the table by filling in the formula for the ionic compound formed by each pair of cations and anions, as shown for the first pair.
Step-by-Step Solution
Verified Answer
To find the formula for the ionic compound formed by a pair of cations and anions, identify the charges of the cations and anions from the periodic table. Then, combine the cations and anions to form a neutral compound by balancing the positive and negative charges using the lowest common multiple or a ratio. Finally, write the chemical formula for the ionic compound using the element symbols and the number of each ion needed to balance the charges.
1Step 1: Identify the charges of the cations and anions
Review the periodic table to determine the charges of the given cations and anions. Remember, cations are positively charged ions, while anions are negatively charged ions. The most common charges for some ions can be determined by their position in the periodic table (for example, alkali metals have a +1 charge while halogens have a -1 charge).
2Step 2: Combine the cations and anions to form a neutral compound
To combine the cations and anions in a way that results in a neutral compound, we need to balance the positive and negative charges. To do this, we can use the lowest common multiple (LCM) of the positive and negative charges or find a ratio that balances the charges.
3Step 3: Write the formula for the ionic compound
Once the ratio of cations to anions has been determined, write the chemical formula for the ionic compound using the element symbols and the number of each ion needed to balance the charges.
Note: In further examples, it's crucial to analyze each given pair of cations and anions and follow these steps to complete the table with the correct formulas for the ionic compounds.
Key Concepts
Cations and AnionsPeriodic Table ChargesChemical Formula Writing
Cations and Anions
Understanding the difference between cations and anions is fundamental to mastering the subject of chemistry, especially when dealing with ionic compounds. As you might recall, cations are positively charged ions, which means they have more protons than electrons. The process of losing electrons leads to a positive charge. On the flip side, anions carry a negative charge as a result of gaining extra electrons, which increases their negative charge relative to protons.
To provide a clearer picture, let's look at common examples. Sodium (Na), a member of the alkali metals group, readily loses one electron to become Na+, a cation. Chlorine (Cl), part of the halogens group, tends to gain an electron forming Cl−, an anion.
In forming ionic compounds, cations and anions attract each other due to their opposite charges. This electrostatic force is what holds the ionic compound together in a stable, crystalline structure. It's important to note that cations and anions combine in ratios that result in an overall neutral charge for the compound.
To provide a clearer picture, let's look at common examples. Sodium (Na), a member of the alkali metals group, readily loses one electron to become Na+, a cation. Chlorine (Cl), part of the halogens group, tends to gain an electron forming Cl−, an anion.
In forming ionic compounds, cations and anions attract each other due to their opposite charges. This electrostatic force is what holds the ionic compound together in a stable, crystalline structure. It's important to note that cations and anions combine in ratios that result in an overall neutral charge for the compound.
Periodic Table Charges
The periodic table is more than just a list of elements; it is a map guiding us through the tendencies of elements to form cations or anions based on their respective charges. The periodic table is arranged in a manner that can help predict the likely charge on an ion when an atom loses or gains electrons.
Elements in groups 1 and 2, for example, are likely to lose electrons and form cations with a +1 and +2 charge respectively. This is due to their low ionization energy. Conversely, nonmetals like oxygen and sulfur in group 16 tend to gain two electrons to achieve a stable electron configuration, resulting in a -2 charge.
By understanding these trends, you can look at the position of an element on the periodic table and have a strong idea about the probable charge of the ions it will form. This knowledge plays a crucial role when predicting and writing the formulas for ionic compounds.
Elements in groups 1 and 2, for example, are likely to lose electrons and form cations with a +1 and +2 charge respectively. This is due to their low ionization energy. Conversely, nonmetals like oxygen and sulfur in group 16 tend to gain two electrons to achieve a stable electron configuration, resulting in a -2 charge.
By understanding these trends, you can look at the position of an element on the periodic table and have a strong idea about the probable charge of the ions it will form. This knowledge plays a crucial role when predicting and writing the formulas for ionic compounds.
Chemical Formula Writing
Writing chemical formulas correctly is a vital skill in chemistry that allows us to communicate compositions of substances succinctly. When it comes to ionic compounds, the goal is to combine cations and anions in a way that the resulting formula is electrically neutral. The process involves three core steps, as outlined in the exercise.
After identifying the charges using the periodic table, find the ratio of cations to anions that will balance out the overall charge. This often involves finding the lowest common multiple of the charges if they are not already balanced. For instance, if you have a magnesium cation (Mg2+) and a oxide anion (O2−), the LCM of 2 and 2 is 2, so one of each ion will balance out to a neutral MgO formula.
Remember, the subscripts in the chemical formula indicate the number of each ion. Using these subscripts appropriately is the key to correctly representing the stoichiometry of the compound. Always strive to reduce these subscripts to their smallest whole number ratio for the simplest formula of the compound.
After identifying the charges using the periodic table, find the ratio of cations to anions that will balance out the overall charge. This often involves finding the lowest common multiple of the charges if they are not already balanced. For instance, if you have a magnesium cation (Mg2+) and a oxide anion (O2−), the LCM of 2 and 2 is 2, so one of each ion will balance out to a neutral MgO formula.
Remember, the subscripts in the chemical formula indicate the number of each ion. Using these subscripts appropriately is the key to correctly representing the stoichiometry of the compound. Always strive to reduce these subscripts to their smallest whole number ratio for the simplest formula of the compound.
Other exercises in this chapter
Problem 62
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