Page 261 - Science Course 3 (Book 1)

Mo7-L3: Vocabulary Review

Direction: On each line, write the term from the word bank that correctly replaces the underlined words in
each sentence. NOTE: You may need to change a term to its plural form.

activation energy catalyst endothermic
enzyme exothermic inhibitor

1. Preservatives in food are substances that slow down, or even stop, a chemical
reaction.

2. An example of the minimum amount of energy needed to start a chemical
reaction is a flame that causes wood to combust.

3. Catalysts that speed up chemical reactions in living cells help break down food
for absorption by the intestine.

4. A(n) substance that increases reaction rate by lowering the activation energy of a
reaction does not increase the amount of product that is made; it only makes a
given reaction happen faster.

5. Burning a log in the fireplace is an example of a reaction that is a chemical
reaction that releases thermal energy.

6. Frying an egg is an example of a reaction that is a chemical reaction that absorbs
thermal energy.

Mo7-L3: Key Concept Organizer

Direction: Use the diagram to respond to each statement on the lines provided.

Breaking a bond absorbs Forming a bond
energy from the releases energy to the
surroundings. surroundings.

Chemical bonds
contain
chemical energy.

Some chemical reactions Some chemical reactions
absorb more energy than release more energy than
they release. they absorb.

1. Explain what happens when chemical bonds break.

2. Explain what happens when chemical bonds form.

3. Contrast what happens to energy in different chemical reactions.

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