Every substance can be represented by a chemical formula. The chemical formula tells you which chemical elements the substance is made of. In a chemical formula, each chemical element is represented by its atomic symbol. The models below represent molecules of three different substances. Each substance has a different chemical formula. Select the model that represents a molecule of the substance with the chemical formula HBr.
For a substance composed of molecules, the chemical formula tells you the number of atoms in each molecule. Each atomic symbol in the chemical formula represents one atom, unless the symbol is followed by a subscript. The subscript shows how many atoms the symbol represents. Select the model that represents a molecule of the substance with the chemical formula H2O2.
Some substances are not composed of molecules. Instead, these substances are composed of atoms arranged in a crystal structure, or repeating pattern. Models that represent these substances show this repeating pattern of atoms. The chemical formula for a substance with a crystal structure shows two things. It shows which chemical elements the substance is composed of. It also shows the ratio, or relative amounts, of the chemical elements in the substance. For example, the chemical formula for beryllium fluoride, BeF2, shows that there is one beryllium atom for every two fluorine atoms. Select the model that represents the substance with the chemical formula BN.
Look at the chemical formula and the model below. Both the chemical formula and the model tell you about the composition of water. But only the model gives you information about the arrangement of the atoms in a water molecule. Match the meanings to the terms.