1. Changes to a substance that do not involve a permanent reordering of atoms are know as a physical change.
2. Changes that reorder atoms to form new molecules, such as the reaction between sodium and chlorine ions to form sodium chloride, are known as chemical change.
3. What does the release or absorption of energy indicate? A chemical change
4. Which of these is an example of a chemical change? firework exploding
5. Which of the following changes can alter the form of a substance but does not necessarily change it to an other substance? all of the above
6. Chemical compounds undergo both physical and chemical changes. Which of the following is an example of a chemical change? salt (NaCl) being dissolved into water
7. In physical science lab, Kim and Dawn added small pieces of magnesium to hydrochloric acid. They observed that bubbles formed, the test tube got hot, and the magnesium disappeared. What is a sign that a chemical reaction has taken place in this experiment? gas is produced
8. .If two poisonous elements are combined chemically, which of the following will be true of the resulting compound? The compound may or may not be poisonous, depending on the chemical properties of the new substance.
9. What type of change is described in the paragraph above? How do you know? This is a physical change, because the two substances were separated physically by boiling.
10. What conclusion should Max draw from his observations? The tablet that was placed in the water changed directly into a gas through a physical change.
11. Which of these is true of a chemical reaction? Energy is either released or absorbed.
12. What should you do to complete this task? To determine the substances, we will compare the physical and chemical properties of the two substances and perform tests to check if they are reacting the same way in the tests performed. If they react the same way, they are same.
13. Which of these is a chemical property of a substance? flammability
14. Atoms in the same _______ of the periodic share the same chemical properties. group (row)
15. Which of the following are physical properties? Check all that apply. conductivity, melting point, malleability, density and solubility
16. Which of the following represent chemical properties? Check all that apply. oxidation, combustibility , oxidation
17. What characteristic of an atom determines its properties? The atomic number of neutrons
