Compounds, Bonding, and Reactions

What is an element?

• ⦁ A pure chemical substance

• ⦁ A physical combination of two or more different substances

• ⦁ A chemical combination of two or more different substances

• ⦁ A type of compound

What is a chemical bond?

• ⦁ A mixture of two or more different substances

• ⦁ A type of compound

• ⦁ An attraction between atoms that forms a chemical combination of atoms

• ⦁ An attraction between atoms that forms a physical mixture of atoms

How many nitrogen atoms are in one molecule of (NH4)2SO4?

• 1

• 2

• 4

• 8

What is a chemical reaction?

• The process of physically combining two different substances

• The process that leads to the change of one set of chemical substances into another

• The process of spontaneously creating new substances from nothing

• The process of changing an element into a completely new element

Complete the statement. __________ are the substances that undergo a chemical change to be become __________.

• ⦁ Reactants, products

• ⦁ Products, reactions

• ⦁ Elements, compounds

• ⦁ Compounds, elements

Which of the following would NOT indicate that a chemical reaction is taking place?

• A burst or light

• A color change

• A temperature change

• A phase change

You mix two liquid substances together and bubbles appear. What does this indicate?

• A solid has formed.

• A gas has formed.

• Condensation has taken place.

• Evaporation has taken place.

What does the Law of Conservation of Mass tell us about chemical reactions?

• ⦁ Matter can be created but not destroyed

• ⦁ Matter can be destroyed but not created

• ⦁ Matter can be created or destroyed

• ⦁ Matter cannot be created nor destroyed

Which of the following is an example of a mixture?

• Oxygen

• Water

• Salt water

• Salt

What is a valence electron?

• An electron in the innermost shell of an atom

• An electron in the outermost shell of an atom

• An electron with a stronger negative charge

• A highly energized electron