1. In NaCO3, how many different elements are there? List them.
Three, Na, C and O
100
6. What does the conservation of mass mean?
Conservation of mass states that we cannot create or destroy matter. It means that was we begin with, will be what we end with.
100
11. What are the starting materials in a chemical equation?
The reactants.
100
16. What is the part of the atom that is responsible for chemical bonds?
Valence electrons are responsible for chemical bonds.
100
21. What is the definition of and endothermic reaction?
A chemical reaction that absorbs energy in the from of heat.
200
2. What are the type and number of atoms in the reactants Zn + CuSO4?
Zn = 1
Cu = 1
S = 1
O = 4
200
7. A chemical equation that has the same number and type of atom on each side of the yield sign is said to be this.
A balanced equation has the same number and type of atom on each side of the yield sign.
200
12. What are the end results of a chemical reaction called?
Products are the end result of a chemical reaction.
200
17. What happens when chemical bonds break and new bonds are formed?
When new chemical bonds are formed that means a chemical reaction has happened.
200
22. What is the definition of a balanced chemical equation? What do you have to do to check this?
A chemical equation is balanced if it has the same number and type of atom on each side of the yield. To find out you have to count the atoms.
300
3. How are coefficients used in chemical equations? What does 2KNO3 mean?
The coefficients tell us how many molecules there are in a chemical equations. 2KNO3 = KNO3 and KNO3
300
8. If a chemical reactions begins with 25g of reactants then, according conservation of mass how much should the products weigh?
25g
300
13. What is the arrow called in a chemical equation, and what does it mean?
The arrow is called a yield symbol and it means that a chemical reaction has happened and that the reactants have formed those products.
300
18. Which of the following pairs of atoms could form an ionic bond?
Na and Ne
K and P
Mg and S
Mg and S. Mg gives or loses two electrons, S takes two electrons.
300
23. What is the definition of an exothermic reaction?
An exothermic reaction gives off energy in the form of heat.
400
4. How many atoms total are there in Pb(NO3)2?
There are 9 atoms total.
400
9. If a chemical equation is in alignment with the conservation of mass then what can be said about the products and reactants?
There will be the same number and type of elements.
400
14. You will see two different numbers in a chemical equation. What are these two numbers and what does each mean?
There are coefficients, these tell you how many molecules there are in a chemical reaction. There are also subscripts, these tell you how many of an atom (or small groups of atoms) are in a chemical formula.
400
19. What columns give or lose electrons? Which columns take electrons?
Columns 1 and 2 give, 16 and 17 take electrons.
400
24. Differentiate between chemical and physical change.
In a chemical change you produce something brand new. In a physical change what you began with is what you end with.
500
5. What is the type and number of each atom in the following equation? CH4 + 2O2 --> CO2 + 2H2O
Reactants: Products:
C = 1 C = 1
H = 4 H = 4
O = 4 O = 4
500
10. Is the following chemical equation in alignment with conservation of mass? SO3 + H2O --> H2SO4 How do you know?
Yes, you have to count the reactants and the products.
500
**Daily Double**
15. Write a balanced equation and label the six parts found in a chemical equation. Describe what three of them mean.
Answers may vary. But must include: chemical symbol, reactants, yield, products, coefficients and subscripts.
500
20. Why is it important for the chemical equation to be written correctly?
It is important so that the reaction is correctly described.