1. Basic Chemistry Review for test

2. What is an atom?

3. Answer:
The basic unit of all matter
Small in size

4. What are the subatomic particles in an atom?

5. Answer
Proton
Neutron
Electron

6. Where are the 3 subatomic particles found?

7. Answer Proton and Neutron – NUCLEUS of the atom (center)
Electrons – found rapidly moving in energy levels (energy clouds)

8. What are the electrical charges to the subatomic particles?

9. Answer Proton = Positive (+) Neutron = Neutral (0)
Electron = Negative (e-)

10. What subatomic particles contribute to the MASS of the atom ?

11. Answer
Proton
Neutron
Remember – the electrons are SOOOO LIGHT that they are not part of the mass (atomic weight)

12. How are atoms considered “electrically equal” or “neutral”?

13. Answer There is an equal number of protons and electrons
If there are more protons – then the atom would have an overall POSITIVE charge
If there are more electrons – then the atom would have an overall NEGATIVE charge

14. Label the following: Use the terms Symbol Atomic Weight (Mass)
Atomic Number

15. Answer
A Atomic Number Symbol Atomic Weight (mass)

16. What are the main elements found in living things?

17. Answer Hydrogen Oxygen Nitrogen Carbon
There is also phosphorus and sulfur, but I only want you to focus on the four listed above.

18. Practice The symbol for Krypton is The mass number for Calcium is
The atomic number for Beryllium is

19. Practice The symbol for Krypton is Kr The mass number for Calcium is
The atomic number for Beryllium is 4

20. What does the coefficient represent?

21. Answer The number of molecules present
LARGE NUMBER written before the element symbol
Ex: 4CO2
There are 4 molecules of carbon dioxide

22. What does the subscript represent?

23. Answer The number of atoms present
SMALL NUMBER written within the chemical formula
Ex: 4CO2
There are 8 atoms of oxygen
Remember to distribute (4 x 2=8)

24. More Practice 5C2H4 How many molecules are present?
How many atoms of Carbon are present?
How many atoms of Hydrogen are present?
How many TOTAL atoms are present?

25. More Practice - Answers
5C2H4
How many molecules are present? 5
How many atoms of Carbon are present? 10 (5x2 – remember to distribute)
How many atoms of Hydrogen are present? 20 (5x4 – remember to distribute)
How many TOTAL atoms are present? (distribute and then add up)
(5x2) = 10
(5x4) = 20
= 30

26. Chemical bonds involve …
A. Electrons
B. Protons
C. Neutrons
D. Valence Electrons

27. ANSWER = Chemical bonds involve …
A. Electrons
B. Protons
C. Neutrons
D. Valence Electrons
Choice D is the most accurate answer here

28. In covalent bonds, electrons are …
Gained
Lost
Shared

29. ANSWER - In covalent bonds, electrons are …
Gained
Lost
Shared

30. Where are valence electrons found?

31. Answer
In the outermost energy level of an atom

32. How many electrons should be in the valence shell to have an atom be considered “Stable and Unreactive”

33. Answer
8 electrons!

34. What rule does this 8 number follow?

35. Answer 8 – OCTET rule ****EXCEPTION****
The outermost energy level will be complete when it contains 8 electrons.
Atoms will gain/lose/share electrons to reach this stability!
****EXCEPTION****
Hydrogen and Helium follow the DUET RULE (can only have 2 electrons in the outermost shell to be stable and unreactive)

36. Which of the following atoms are unstable and reactive?
Carbon
Neon
Helium
Magnesium

37. ANSWER - Which of the following atoms are unstable and reactive?
Carbon – 4 opportunities to bond (vacancies)
Neon
Helium
Magnesium – 6 opportunities to bond (vancancies)
Neon is stable because it is a noble gas – already has 8 electrons
Helium is stable because it is also a noble gas – but follows duet rule so it has 2 electrons

38. What’s the difference between a…
Single Bond
Double Bond
Triple Bond

39. What’s the difference between a…
Single Bond
Atoms share 2 electrons (1 pair)
Double Bond
Atoms share 4 electrons (2 pairs)
Triple Bond
Atoms share 6 electrons (3 pairs)

40. What does a structural formula tell us?

41. Answer - Types of Elements Number of atoms Location of atoms Example –
1 Oxygen
2 Hydrogen

42. What do the lines represent in a structural formula ?

43. Answer
COVALENT BONDS
SHARING OF ATOMS!!

44. Draw the Lewis Dot Structure of
Phosphorus
Hydrogen
Nitrogen
Oxygen

45. ANSWER Draw the Lewis Dot Structure of
Phosphorus
Hydrogen
Nitrogen
Oxygen

46. This is the bohr model for what compound?

47. Answer
WATER

48. What is the structural formula for C2H6

49. Answer

50. What is a chemical reaction?

51. Answer Changes or transforms one set of chemicals into another
CHANGES to the BONDS – breaking and reforming bonds

52. What’s the difference between…
Reactants
Products

53. ANSWER What’s the difference between…
Reactants
ENTER into a chemical reaction (before the arrow)
Products
PRODUCED by a chemical reaction (after the arrow)

54. Label the diagram using the following terms…
Reactants
Products
Coefficients
Subscripts

55. ANSWER Label the diagram using the following terms…
C - Reactants
D - Products
A - Coefficients
B – Subscripts
Reactants REACTto produce PRODUCTS

56. What is the Law of Conservation of Matter?

57. Answer Matter cannot be created nor destroyed
Arrangement of atoms is what is changed
# each atom in Reactants must equal # each atom in products
The mass of reactants = the mass of products

58. Is this equation balanced?
Na + Cl2  NaCl

59. Is this equation balanced?
ANSWER - NO
2Na + Cl2  2NaCl

60. What are the properties of water ?

61. Water is polar It has polar covalent bonds between the atoms
It has hydrogen bonds between the molecules (weaker than covalent)
Cohesion, adhesion, liquid is more dense than the solid, high heat capacity, universal solvent