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Atoms and molecules. Matter. Elements rarely occur in pure form in the earth’s crust. Instead they are generally found in combination with other elements. When the atoms of two or more elements are chemically united, the resulting substance is called a compound .
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Matter • Elements rarely occur in pure form in the earth’s crust. • Instead they are generally found in combination with other elements. • When the atoms of two or more elements are chemically united, the resulting substance is called a compound. • A compound is a new substance with properties different from those of the elements that compose it.
Matter • The smallest complete unit of a compound is called a molecule. • Ex: Water (H2O) • Some elements exist naturally as diatomic molecules, molecules made up of two atoms. • Ex: Hydrogen (H2) and Oxygen (O2).
What is the smallest particle of a covalent compound that shows the properties of that compound? • An ion. • An atom. • An element. • A molecule.
The smallest particle of an element that still retains the element’s properties is an • Compound. • Atom. • Isotope. • Mineral.
Name a molecule that is made up of atoms of the same element? • Oxygen • Carbon • Copper • Aluminum
Name a molecule that is also a compound, or is made up of atoms of different elements. • Water • Oxygen • Hydrogen • Iron
What does the “2” represent in the formula for water? • 2 oxygen atoms • 2 hydrogen atoms • 1 hydrogen and 1oxygen • None.
What are the different elements in this compound (C12H22O11)? • Carbon only. • Carbon and hydrogen.. • Carbon, hydrogen and oxygen. • Hydrogen and oxygen.