Pure Substances and Mixtures
Two classifications of matter are pure substances and mixtures. Pure substances have a definite chemical composition, cannot be separated by physical means, and consist of one or more types of atoms.
Mixtures do not have a definite chemical composition, can be separated by physical means, and consist of two or more types of substances.
A student constructs models of elements, molecules, compounds, and mixtures using different colors of balls and black plastic sticks. A key for each element and the chemical bond is shown.
Multiple Choice Question
The student makes a model of ozone, which consists of three oxygen atoms. The model is shown.
Three blue balls are connected together by two black sticks in an upside-down v shape.
Which statement best categorizes ozone as an element or a molecule?
A.
A molecule, because the model consists of one type of atom held together by chemical bonds
B.
An element, because the model consists of one type of atom held together by chemical bonds
C.
A molecule, because the model consists of one type of atom and is not held together by chemical bonds
D.
An element, because the model consists of one type of atom and is not held together by chemical bonds
1 answer
The correct answer is:
A. A molecule, because the model consists of one type of atom held together by chemical bonds.
Ozone (O₃) is indeed a molecule formed from three oxygen atoms bonded together, making it a type of molecule. It consists of only one type of atom, which is oxygen.
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