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Ch.3 Matter and Energy
Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 14th Edition
Timberlake14thChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9781292472249Not the one you use?Change textbook
Chapter 3, Problem 1a

Classify each of the following pure substances as an element or a compound:
b. hydrogen peroxide (H2O2)

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1
Step 1: Understand the definitions of an element and a compound. An element is a pure substance that consists of only one type of atom and cannot be broken down into simpler substances by chemical means. A compound is a pure substance composed of two or more different elements chemically bonded together in a fixed ratio.
Step 2: Analyze the chemical formula of hydrogen peroxide, H₂O₂. The formula indicates that it contains two hydrogen (H) atoms and two oxygen (O) atoms.
Step 3: Determine if the substance consists of only one type of atom or multiple types of atoms. Since H₂O₂ contains both hydrogen and oxygen atoms, it is composed of more than one type of element.
Step 4: Confirm that the elements in H₂O₂ are chemically bonded together. The hydrogen and oxygen atoms in H₂O₂ are bonded through covalent bonds, forming a single pure substance.
Step 5: Conclude that hydrogen peroxide (H₂O₂) is a compound because it is made up of two different elements (hydrogen and oxygen) chemically bonded together in a fixed ratio.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Element

An element is a pure substance that cannot be broken down into simpler substances by chemical means. It consists of only one type of atom and is represented on the periodic table. Examples include hydrogen (H), oxygen (O), and carbon (C). Elements are the fundamental building blocks of matter.
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Compound

A compound is a pure substance formed when two or more different elements chemically bond together in fixed proportions. Compounds have unique properties that differ from the individual elements that compose them. For example, water (H₂O) is a compound made from hydrogen and oxygen, while hydrogen peroxide (H₂O₂) is another compound formed from the same elements in a different ratio.
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Chemical Formula

A chemical formula is a symbolic representation of a compound that indicates the types and numbers of atoms present. For instance, the formula H₂O₂ for hydrogen peroxide shows that it contains two hydrogen atoms and two oxygen atoms. Understanding chemical formulas is essential for classifying substances as elements or compounds and for predicting their chemical behavior.
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