Question

Which of the following contains an element, a compound, and a mixture? a. copper, silicon dioxide \(\left(\mathrm{SiO}_{2}\right),\) copper \((\mathrm{II})\) sulfate \(\left(\mathrm{CuSO}_{4}\right)\) b. hydrogen, carbon dioxide \(\left(\mathrm{CO}_{2}\right),\) water \(\left(\mathrm{H}_{2} \mathrm{O}\right)\) c. chili, pizza, steak d. sodium, sodium chloride \((\mathrm{NaCl}),\) salt water e. nitrogen, argon, air

Short answer

The correct choice is option D, which contains an element (sodium - Na), a compound (sodium chloride - NaCl), and a mixture (salt water).

Step-by-step solution

Option A

In option A, we have: 1. Copper (Cu): is an element found on the periodic table. 2. Silicon Dioxide (SiO2): is a compound made up of two elements, silicon (Si) and oxygen (O). 3. Copper (II) Sulfate (CuSO4): is also a compound, formed from copper (Cu), sulfur (S), and oxygen (O). Therefore, option A doesn't have a mixture, so it's not the correct choice.

Option B

In option B, we have: 1. Hydrogen (H): is an element found on the periodic table. 2. Carbon Dioxide (CO2): is a compound made up of carbon (C) and oxygen (O). 3. Water (H2O): is also a compound, made from hydrogen (H) and oxygen (O). This option doesn't contain a mixture either, so it's also not the correct choice.

Option C

In option C, we have: 1. Chili: which is a mixture of different ingredients like meat, beans, tomatoes, etc. 2. Pizza: which is also a mixture of ingredients like dough, cheese, and sauce. 3. Steak: is not an element or a compound; it's a food item. This option doesn't have an element and a compound, so it's not the correct choice.

Option D

In option D, we have: 1. Sodium (Na): is an element found on the periodic table. 2. Sodium Chloride (NaCl): is a compound made up of sodium (Na) and chlorine (Cl). 3. Salt Water: which is a mixture containing sodium chloride (NaCl) dissolved in water (H2O). Option D contains an element, a compound, and a mixture. Therefore, it's the correct choice.

Option E

In option E, we have: 1. Nitrogen (N): which is an element found on the periodic table. 2. Argon (Ar): which is also an element found on the periodic table. 3. Air: which is a mixture of gases like nitrogen, oxygen, and argon. This option contains two elements and a mixture, but it doesn't have a compound, so it's not the correct choice.

Key concepts

Elements

Elements are pure substances that consist of only one type of atom. They are the simplest form of matter and cannot be broken down into simpler substances by chemical means. The periodic table organizes all known elements into a tabular format where each element is represented by a unique symbol. Some well-known elements include:

• Copper (Cu)
• Hydrogen (H)
• Sodium (Na)
• Nitrogen (N)

Each element has distinct physical and chemical properties. For instance, copper is known for its excellent electrical conductivity and distinct reddish color, while hydrogen is a colorless, odorless gas at room temperature.
Understanding elements is fundamental in chemistry, as they are the basic building blocks of all compounds and mixtures.

Compounds

Compounds are substances formed when two or more elements chemically combine in fixed proportions. This chemical combination results in new substances with properties different from their individual elements. Unlike mixtures, compounds can only be separated into their individual elements through chemical reactions.

• Silicon Dioxide (\( ext{SiO}_2 \)): Made from silicon and oxygen.
• Carbon Dioxide (\( ext{CO}_2 \)): Composed of carbon and oxygen.
• Sodium Chloride (\( ext{NaCl} \)): Formed from sodium and chlorine.

A familiar example of a compound is water (\( ext{H}_2 ext{O} \)), which consists of hydrogen and oxygen. While hydrogen and oxygen are gases at room temperature, their compound, water, is a liquid essential for life.
Understanding the nature of compounds helps us predict the outcomes of chemical reactions and the properties of new materials formed from different elements.

Mixtures

Mixtures are combinations of two or more substances that are not chemically bonded. Unlike compounds, the components of mixtures retain their individual properties and can be separated by physical means such as filtration, distillation, or decanting. Mixtures can be:

• Homogeneous: where the composition is uniform throughout, like salt water, in which the salt is evenly dissolved in the water.
• Heterogeneous: where the different components are visible and not evenly distributed, like chili or pizza, which contain a variety of ingredients in distinct layers or chunks.

Mixtures are very common in everyday life, evident in foods, air, and other materials we encounter daily. They allow flexibility in creating materials with tailored properties, as the ratios of individual components can be adjusted to suit specific needs.