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Atoms and Molecules
All substances, whether they are elements, compounds, or mixtures, are made up of tiny particles. These particles are either individual atoms or groups of atoms called molecules.

Vocabulary
atom: extremely tiny particles of matter. An atom is the smallest particle of an element that can exist. All substances are made up of atoms.
elements: substance that contains just one type of atom
compounds: substance that contains two or more different elements joined together by chemical bonds
mixtures: substance made up of two or more elements or compounds that are not joined together by chemical bonds
particles: small piece of a substance
molecules: type of particle made up of two or more atoms joined together by chemical bonds
elements: substance that contains just one type of atom
compounds: substance that contains two or more different elements joined together by chemical bonds
mixtures: substance made up of two or more elements or compounds that are not joined together by chemical bonds
particles: small piece of a substance
molecules: type of particle made up of two or more atoms joined together by chemical bonds
Experiment: Reactive Metals
Problem: Which common metals are most reactive?
Hypothesis: To discover which metals are most reactive, we can put pieces of the metals in a weak acid and watch what happens. The one that fizzes most quickly will be the most reactive.
Hypothesis: To discover which metals are most reactive, we can put pieces of the metals in a weak acid and watch what happens. The one that fizzes most quickly will be the most reactive.
Materials:
nail made of iron or steel
galvanized (zinc-coated) nail
nail made of copper or brass
white vinegar
three small jars
one bowl
nail made of iron or steel
galvanized (zinc-coated) nail
nail made of copper or brass
white vinegar
three small jars
one bowl
Experiment Steps
1. Put a nail into each of the three small jars. Pour just enough vinegar into the jars to cover the nails. Watch what happens for a few minutes. While you wait, ask an adult to heat a kettle of water.
1. Put a nail into each of the three small jars. Pour just enough vinegar into the jars to cover the nails. Watch what happens for a few minutes. While you wait, ask an adult to heat a kettle of water.
When you are finished, answer the problem question using the link to the right!