Chemical Reactions
7th Grade Science · 9 lessons
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Lessons
- 1The Periodic TableThe periodic table organizes elements by their properties. Elements in the same column (group) have similar characteristics, such as the noble gases which rarely react.Experiment
- 2Conservation of MassConservation of mass means that matter cannot be created or destroyed in a chemical reaction. If you start with 10 grams of reactants, you end with 10 grams of products.Experiment
- 3Endothermic and ExothermicEndothermic reactions absorb heat from surroundings, making things feel cold. Exothermic reactions release heat, like combustion. Both types of reactions are essential in nature.Experiment
- 4Reading Chemical FormulasChemical formulas show the types and numbers of atoms in a molecule. CO₂ has one carbon and two oxygen atoms. The subscript tells how many of each atom.Lesson
- 5The Law of Definite ProportionsThe law of definite proportions states that a compound always contains the same elements in the same ratio by mass. Water is always 11.2% hydrogen and 88.8% oxygen.Experiment
- 6DistillationDistillation separates mixtures based on different boiling points. Heating salt water causes water to evaporate and condense, leaving salt behind and producing fresh water.Experiment
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