1. Atomic Structure & Periodic Table review
8th Grade Science Quick Review
Dana Frank

2. Which of the following is the most accurate representation of an atom
Which of the following is the most accurate representation of an atom? Justify your answer. 1 2 3 4

3. Label the protons, neutrons & electrons What is the charge of each Where is most of the mass of an atom located? Most of the space? 3

4. An atom has an atomic number of 1, what can you infer about its structure? An ion has an atomic number of 3, what can you infer about its structure?

5. Calculate the mass of the following atoms
Find the number of protons, neutrons and electrons for each of the following neutral atoms
Calcium
Chlorine
Calculate the mass of the following atoms
Element A has 12 protons, 13 neutrons & 12 electrons
Element B has 9 protons, 7 neutrons & 9 electrons

6. What are the 3 classes of elements on the periodic table
What are the 3 classes of elements on the periodic table? What are the properties of each? Where are they located on the periodic table?

7. Periodic Table Trends
Find 2 elements with 2 valence electrons Find 3 elements with 3 energy levels Find 3 elements with similar properties

8. Describe the properties of these groups/families
Alkali metal
Halogen
Noble Gas
Alkaline Earth Metal

9. Use the table….. What do Na, K and Rb have in common?
What do Mg, P and Cl have in common?
Dull, brittle and non conductive best describes which of the following: Pd, S, Mg, Fe
Which of the following elements are very reactive: Au, Fe, Cl, Zn
How are groups 1, 2 and 17 different from transition metals (groups 3-12)?

10. Describe the changes in element properties as you move from left to right across period # 4 Why do most atoms form compounds or molecules?

11. D F E B A C
An element does not form compounds with other elements ______
An element has 6 energy levels _____
A reactive element with 1 valence electron _______
A relatively stable, malleable element _______
Two elements with similar properties _____ ______

12. Conservation of Mass Reaction Rate
review

13. How can you affect the rate of a reaction?

14. Increase or decrease the number of successful collisions between atoms
Temperature…. increase temp, increase the number of successful collisions
Surface area…increase surface area, increase the number of successful collisions
Concentration of reactants…increase concentration, increase the number of successful collisions
Add a catalyst..lowers the energy required for the reaction to take place or better aligns reactants

15. Reactants and Products
Identify the reactants in the following reactions 2Na + 2H2O  2NaOH + H2

16. Reactants and Products
Identify the products in the following reactions 2Ag2O  4Ag + O2

17. Law of conservation of mass
What is the law of conservation of mass? How does it relate to chemical reactions?

18. Law of conservation of mass
What is the law of conservation of mass?
Matter is not created or destroyed
Mass of reactants = mass of products
Total mass stays the same during a reaction
How does it relate to chemical reactions?
Chemical reactions must be balanced
Same elements present in reactants and products
Same number of each element in reactants and products.

19. Before balancing an equation, you need to know how to read a formula
2NaOH
8H2
4Ag
What are the subscripts for each
of the following formulas?
What if an element doesn’t have
a subscript?
What information does the
subscript tell you?

20. Before balancing an equation, you need to know how to read a formula
2NaOH
8H2
4Ag
What are the subscripts for each
of the following formulas?
What if an element doesn’t have
a subscript? We assume it’s a “1”
2H2O1
2Na1O1H1
What information does the
subscript tell you? The number of
atoms of each element in a
molecule.

21. Before balancing an equation, you need to know how to read a formula
8H2SO4
What are the coefficients for each
of the following formulas?
What if a reactant doesn’t have
a coefficient?
What information does the
coefficient tell you?

22. Before balancing an equation, you need to know how to read a formula
8H2SO4
What are the coefficients for each
of the following formulas?
What if a reactant doesn’t have
a coefficient? Then we assume it is
a “1”
e) 1O2 
What information does the
coefficient tell you? How many
molecules of a reactant are present
in a reaction

23. Rules for balancing a chemical equation
Change the coefficients (BIG NUMBERS),
do not change the subscripts (little numbers)
Why:?
If you change the subscript, you change the identity (and properties) of the substance.
C6H12O6 is sugar
C4H6O2 is white glue
C3H8O is isopropyl alcohol

24. Check to see if these are balanced if they aren’t balanced, balance them
P O  P2O5
NaCl F2  NaF Cl2

25. Check to see if these are balanced if they aren’t balanced, balance them
4P O  P2O5
CH O  CO H2O
2NaCl F2  NaF Cl2

26. Sometimes you are asked to demonstrate the law of conservation of mass this way…
40 g of Ca reacts with 71 g of Cl to produce _____ g of CaCl.
2. _____ g of potassium reacts with 16 g of oxygen to produce 94 g of potassium oxide.
3. 14 g of lithium react with _____ g sulfur to produce 46 g of lithium sulfide.
4. 24 g of magnesium reacts with 38 g of fluorine to produce _____ g magnesium fluoride.

27. Which of the following shows mass being conserved during a reaction?
2C8H O2  6CO2 + 18H2O b
2H2 + O2  2H2O c
2HgO  Hg + O2 d
2FeO2  Fe2 + O3

28. Which of the following shows mass being conserved during a reaction?
2C8H O2  6CO2 + 18H2O b
2H2 + O2  2H2O c
2HgO  Hg + O2 d
2FeO2  Fe2 + O3
Because it is balanced,
it shows that the mass during the reaction stayed the same

29. Every chemical reaction obeys the law of conservation of mass…
Every chemical reaction obeys the law of conservation of mass….but, sometimes a reaction makes it hard to observe.
What type of reaction circumstance would make it difficult to observe or measure the law of conservation of mass?

30. Every chemical reaction obeys the law of conservation of mass…
Every chemical reaction obeys the law of conservation of mass….but, sometimes a reaction makes it hard to observe.
What type of reaction circumstance would make it difficult to observe or measure the law of conservation of mass? An open system/container and gas as a reactant or product…..because if the system isn’t closed, the mass of the gas cannot be accounted for.

31. Review questions
What parts of an atom are involved in a chemical reaction? Why? What are the three types of physical changes? What is the difference between a physical and a chemical change? How do you know a chemical change has occurred?

32. A forklift uses liquid natural gas (LNG) as a fuel source
A forklift uses liquid natural gas (LNG) as a fuel source. LNG is created by cooling and compressing the gas enough to transform it into a liquid state. During operation, the forklift engine converts the LNG to carbon dioxide and water. The process also releases heat. While operating the forklift, its operator collides with a stack of pallets and severely dents the frame of the lift. While examining the damage, the supervisor notices that a large area of the surface of the forklift has become orange with rust Identify the physical changes in the passage above. Explain your response. Identify the chemical changes in the passage above. Explain your response.