Question

Write chemical formulas for compounds containing: (a) one calcium atom for every two iodine atoms (b) two nitrogen atoms for every four oxygen atoms (c) one silicon atom for every two oxygen atoms (d) one zinc atom for every two chlorine atoms

Short answer

The chemical formulas for the compounds are (a) CaI2, (b) NO2, (c) SiO2, and (d) ZnCl2.

Step-by-step solution

Identify the Chemical Symbols

Find the chemical symbols for the elements involved in each compound. Calcium is Ca, iodine is I, nitrogen is N, oxygen is O, silicon is Si, zinc is Zn, and chlorine is Cl.

Determine the Ratio of Atoms

Understand the given ratio of atoms for each compound. For example, in (a), the ratio is one calcium atom to two iodine atoms.

Write the Chemical Formulas

Use the atomic ratios to write the chemical formula. Remember that for ionic compounds, the overall charge must be neutral.

Formula for (a)

Since the ratio is one calcium atom to two iodine atoms, the chemical formula is CaI2.

Formula for (b)

For two nitrogen atoms to four oxygen atoms, the simplest ratio is 1:2, which makes the chemical formula N2O4 or simplified further to NO2.

Formula for (c)

With a one silicon atom to two oxygen atoms ratio, the chemical formula is SiO2.

Formula for (d)

One zinc atom for every two chlorine atoms gives us the chemical formula ZnCl2.

Key concepts

Chemical Symbols

Understanding chemical symbols is the fundamental first step in writing chemical formulas. Each chemical element is assigned a unique one or two-letter symbol based on its Latin name. For instance, hydrogen is represented by the symbol 'H', while calcium is represented by 'Ca'. These symbols are standardized and used universally, which allows scientists and students all over the world to communicate chemical information efficiently and without confusion.

In any given chemical formula, the elements present are represented by their respective symbols. For example, in the provided exercise, calcium's symbol 'Ca' is paired with iodine's symbol 'I'. It’s crucial to memorize these symbols or have a periodic table handy when writing chemical formulas to ensure accuracy. As in programming or mathematics, where each symbol has a specific meaning and function, chemical symbols serve as the 'alphabet' of chemistry, and learning them is essential for proficiency in the subject.

Atomic Ratio

The atomic ratio in a chemical formula indicates the number of atoms of each element present in the compound. It's like a recipe that shows how much of each ingredient is needed to make the final product. When writing chemical formulas, understanding the atomic ratio helps you determine the correct proportions of atoms.

For instance, the exercise states there should be one calcium atom for every two iodine atoms; this 1:2 atomic ratio is denoted in the formula as CaI2. In chemistry, it’s important to keep these ratios balanced to reflect the actual quantities you’d encounter in a lab or in nature. Sometimes, ratios can be simplified. For instance, the ratio of two nitrogen atoms to four oxygen atoms simplifies to 1:2, yielding the formula NO2, which represents a more simplified view of the actual compound.

Ionic Compounds

Ionic compounds are chemical substances made up of positively charged ions, called cations, and negatively charged ions, called anions. These ions are held together by ionic bonds, which are electrical attractions between oppositely charged ions.

When writing formulas for ionic compounds, the aim is to achieve a neutral overall charge. This involves balancing the charges of the cations and anions. In our exercise, for example, calcium (Ca) typically carries a +2 charge as a cation, while iodine (I) carries a -1 charge as an anion. Therefore, to balance out the charges, two iodine atoms are needed for every one calcium atom, resulting in the neutral compound CaI2. Understanding the balance of charges in ionic compounds is key to writing their chemical formulas correctly.

Chemical Compound Notation

Chemical compound notation is a system of symbols and numbers used to represent the composition of chemical compounds. This notation includes the chemical symbols for the elements involved along with subscript numbers that indicate the atomic ratio of each element in the compound.

The chemical formula for a compound is a concise representation of its composition. For example, SiO2 tells us that for each silicon atom, there are two oxygen atoms in the compound. Moreover, chemical formulas may also be simplified to reflect the smallest whole-number ratio of atoms, as in the formula NO2 for nitrogen dioxide, which is a simplified version of N2O4.

Appreciating these notations allows one to decipher and visualize the microscopic structure of compounds. Just as a blueprint provides a visual representation of a building, the chemical compound notation provides a snapshot of the molecular structure of a compound.