Unit 2 Study Guide

The energy required to start a chemical reaction is ___.

• Endothermic

• Exothermic

• Activation

• Released

Energy is _____ when new bonds form.

• Absorbed

• Released

• Gained

• Lost

Energy is ______ when bonds break.

• Gaiined

• Lost

• Released

• Absorbed

An _______ reaction is when more thermal energy is absorbed than is released.

• Endothermic

• Exothermic

An _______ reaction is when more thermal energy is released than is absorbed.

• Exothermic

• Endothermic

Which observation(s) might be used as evidence that a chemical reaction occurred?

• Color change

• Properties change

• Odor change

• All of the above

_________ is (are) made of more than one atom.

• Molecules

• Protons

• Neutrons

• An element

Which is an example of a physical change?

• Burning wood

• Freezing water

• Rust on a car

• Cooking food

Which is an example of a chemical change?

• Burning wood

• Cooking food

• Rust on a car

• All of the above.

Which of the following help a chemical reaction to happen faster?

• Molecule

• Atom

• Catalyst

• Density