Breaking and Forming Bonds in Reactions

Start with Interpret Coefficients, Subscripts and State Symbols so students can read equations, then move to the particle diagram and balancing sheets. Use the data sheets on reaction rate, cold packs and unknown powders as lab style practice.

Classify reactions such as burning methane as exothermic or endothermic from bond energy. The directions on the page read: Read the text and diagrams. Then answer the questions on page 2. An answer key is included.

Yes, both. We made it for 8th grade matter, and it works the same at home or at school. At home, a student can work through it alone and then go over it with you, which shows quickly what is solid and what needs another look. In class it works as independent practice, homework or a warm-up, and you can print one copy or a full set.

Change only the coefficients, the big numbers in front, until each kind of atom matches on both sides. Changing a subscript would make a different substance. Balance Equations With Polyatomic Groups shows how to count a group such as SO4 as one unit when it stays whole.

Atoms are never created or destroyed in a reaction, they only rearrange into new substances. In a closed system the total mass stays the same. In an open system a gas can escape or join from the air, so the measured mass can change, as on Conservation of Mass in Open and Closed Systems.

Compare the properties of the substances before and after, such as density, melting point and whether they dissolve. If the properties change, a new substance formed. Use Properties to Decide If a Reaction Happened compares four tests, from dried sugar to burned magnesium.

Temperature, surface area, concentration and catalysts all change how often particles collide with enough energy. What Changes the Speed of a Reaction explains each factor, and Graph How Temperature Changes Reaction Time has students graph antacid fizzing times.