Parts of a chemical Reaction & Exo and Endo

What is the little number after an element in a chemical equation called.
Example: H₂

• Coefficient 
• Subscript
• Atom
• Equation

What is the number before a chemical formula called?
Ex: 2H₂ + O₂ --> 2H₂O

• Coefficient
• Subscript
• Atom
• Equation

How many Al atoms are in this compound?         4Al₂O₃

• 2
• 8
• 6
• 4

Number of H in 3(NH₄)₂CrO₄

• 4
• 6
• 8
• 24

What is a chemical equation?

• Describes the number of elements in a compound.

• One or two letters that represent the elements on the periodic table.

• The number to the lower right of an element that shows the number of atoms bonded.

• A written description of a chemical reaction.

In a chemical reaction, molecules in the reactants interact to form...

• new substances (the products)

• They don't interact.

• the same substances (physical change)

What is the left part of a chemical equation called?
2H_{2 +} O₂ --> 2H₂O

• Reactants
• Products 
• Yields 
• Chemical Equation 

What is the right part of a chemical equation called...
2H_{2 +} O₂ --> 2H₂O

• Reactants
• Products 
• Yields 
• Chemical Equation 

Which of these is evidence that a chemical reaction took place in this picture?

• production of a gas

• formation of a precipitate

• color change

When you mix two liquids and get a solid like these examples, that's called a _____________.

• precipitate

• color change

• change in state