1. Midterm Review Chemistry Level 2

2. Chapter 1 What is chemistry? What is matter?
The field of science that studies the composition and structure of matter
What is matter?
Anything that has mass and occupies space
  Be able to describe each step of the scientific method. Provide a couple examples where you used the scientific method to solve a problem in your life and label each part.
State a Problem, Hypothesis, Experiment, Reach a Conclusion

3. Chapter 1 - Continued
Theory v. Scientific Law --- What is the difference? Think of examples for both and identify the limitations. Can they be proved/disproved supported/falsified? Which one is more powerful than the other?
Law summarizes observations but theories provide an explanation
Limitations:
A scientific Theory CAN NEVER BE PROVED

4. Chapter 1 - Continued
What are variables? What step of the scientific method involves manipulating variables?
Variables are factors that can change
Experimenting
In large, why has science advanced as much as it has over the years?
Advancements in science has taken part largely because of advancements in technology

5. Chapter 2 Name some examples of physical properties.
Mass, volume, density, boiling point, melting point, solubility, phase (solid, liquid or gas), color, texture, hardness, etc…

6. Chapter 2 (continued)
Define the particle arrangement of a solid, liquid and gas. What can you say about their shapes and the volume they occupy?
 Solids have an orderly arrangement of particles with a definite shape and a definite volume
Liquids have a less orderly arrangement of particles with no definite shape and definite volume
Gases have a random arrangement of particles with no definite shape and no definite volume.

7. Chapter 2 (continued)
Identify physical properties from chemical properties. For example zinc metal is hard, silver in color, is easily shaped and reacts vigorously with hydrochloric acid. What are some physical and chemical properties of zinc?
Physical
Metal, hard, silver, malleable
Chemical
Reacts with hydrochloric acid

8. Chapter 2 (continued)
What is the difference between a physical and chemical change? How do you know when one occurred? Think of examples.
 A physical change is one in which the substance still retains its identity
Evaporating, breaking, bending, cutting, etc…
A chemical change is one in which its chemical identify has changed
Rusting, burning, explosion, decaying, etc…

9. Chapter 2 (continued)
What are symbols? What are formulas? When should you capitalize letters? What are subscripts?
Symbols represent elements
Formulas represent compounds
The first figure in a properly written chemical symbol always is capitalized.

10. Chapter 2 (continued)
An object has a volume of 12mL and a mass of 3.5g. What is the object’s density?
 0.29 g/mL
An object has a mass of 357g and volume of 75mL. What is the object’s density?
 4.8 g/mL
An object has a mass of 4.2g and a volume of 19.3mL. What is the object’s density?
0.22 g/mL

11. Chapter 3
What is an advantage of the metric system compared to the English system?
Based on a power of 10
What is the SI unit of mass? What is the SI unit for temperature?
 kilogram – mass
Kelvin - temperature
Define weight. Does weight change based on location?
 the pull on a given mass by gravity
the weight of an object depends on its location
Which temperature scale has no negative numbers?
Kelvin

12. Chapter 3 (continued) Convert the following:
50oC = ___323_______K
-25oC = ___248___K
Count the number of significant figures in these problems
50,400 mg = _____3_______
kg = _____2_______
mg = _____6______
L = _______5_______

13. Chapter 3 (continued)
Round problems 1-4 to two significant figures and write the answer in scientific notation. 50,400 mg = ____5.0 X 104 mg________ kg = ____4.6 X 10-4 kg_______ mg = ____9.2 X 102 mg______ 1,045 L = _______1.0 X 103 L______

14. Chapter 3 (continued)
Review rules regarding adding/subtracting and multiplying/dividing
What is the result of adding g +4.5g = 6.5 g
What is result of subtracting m – 3.6m = 0.8 m
What is the result of multiplying 5.2 X 102 by X 10-4m = 7.1 X 10-2 m
What is the result of dividing 4.3 X102 by 2.0 X 104g = 2.2 X 10-2 g

15. Chapter 3 (continued) Define density.
Ratio of an object’s mass to its volume
Density is found by dividing mass by volume
volume = 90.0 g density = 0.70g/mL mass = 63 g
mass = 55 g density = 12.3 g/mL volume = 4.5 mL
mass = 7.0 g volume = 9.1 cm3 density = 0.77 g/cm3
What is the density of an object that has a mass of 5.6g and a volume of 25cm3?
0.22 g/cm3

16. Chapter 4 Fill in the table below: Proton Positive (+) 1 amu
Charge
Mass
Location
Proton
Positive (+)
1 amu
In nucleus
Neutron
No charge
Electron
Negative (-)
0 amu
Outside nucleus

17. Chapter 4 (continued)
What does the atomic number of an element indicate?
 # of protons
What does the mass number of an element indicate?
number of protons + neutrons
If an atom has an atomic number of 36 and a mass number of 84 how many protons, neutrons and electrons are present in this atom?
36 Protons, 36 electrons, and 48 neutrons

18. Chapter 4 (continued) What does the number 13 represent in carbon-13?
Mass Number (number of protons and neutrons)
How do you calculate the number of neutrons in an atom?
Mass Number - # of Protons = # of Neutrons 
Who was Democritus?
One of the first to suggest the idea of atoms ( B.C.)
What is the unit that is used to measure a weighted average atomic mass?
Amu (atomic mass unit)

19. Chapter 4 (continued) What is an isotope? What is an ion?
Isotopes of the same element have different numbers of neutrons
What is an ion?
Ions are atoms that have number of protons not equal to electrons
How many protons, neutrons and electrons are present in this neutral atom? 3919K
19 protons, 19 electrons, and 20 neutrons

20. Chapter 5 Describe the quantum mechanical model of an atom?
Based on the probability of finding an electron
Which scientist developed the quantum mechanical model of an atom?
Erwin Schrödinger
What are the shapes of an s and p orbitals?
S is a spherical shape
P is a dumbbell shape

21. Chapter 5 (continued)
What is a principal energy level, sublevel and atomic orbital?
Principal energy level contains one or more types of sublevels
Sublevels are atomic orbital shape represented by the following letter s, p, d and f
Atomic orbitals are the regions of space where electrons are located in the different sublevels

22. Atomic Orbitals
P sublevel
S sublevel
1s 2s 2p
Atomic Orbitals
Principal Energy Level 2
Principal Energy Level 1

23. Chapter 5 (continued)
What is the maximum number in each s, p, d and f orbitals?
S (1 orbital), p (3 orbitals), d (5 orbitals), f (7 orbitals)
What types of atomic orbitals are in the 1st, 2nd and 3rd principal energy levels?
1st (s atomic orbitals)
2nd (s and p)
3rd (s, p, and d)

24. Chapter 5 (continued)
If the spin of one electron is clockwise in an orbital the spin on the second electron must be counterclockwise?
Using the Aufbau diagram what orbital would come after 3p? 4s
What is the number of electrons in the outermost energy level of sulfur? 6

25. Chapter 5 (continued)
What happens when an electron moves from a lower to higher energy level?
absorb a quantum of energy
When an electron moves from a higher to lower energy level what happens?
lose a quantum of energy
When does emission of light occur?
Drops from a higher to lower energy level

26. Chapter 5 (continued)
Which of the following quantum leaps would be associated with the greatest energy emitted?
n = 4 to n=2
n = 5 to n= 1

27. Chapter 5 (continued)
How are frequency and wavelength of light related?
They are inversely proportional to each other
Which variable is directly proportional to energy?
frequency
Define a photon.
Quanta of light

28. Chapter 5 (continued)
What is the wavelength of a radiation with a frequency of 5 X 1018 Hz (s-1)? (c = 3.00 X 108 m/s)
6 X m
What is the frequency of light having a wavelength of 4.2 X 10-8m?
7.1 X m
What is the energy of a photon with a frequency of 2.5 X 1015 Hz? [E = h v] (h = 6.63 X J s)
1.7 X J

29. Chapter 5 (continued)
What are the electron configurations for the following elements:
Na: 1s2 2s2 2p6 3s1
Ar: 1s2 2s2 2p6 3s2 3p6
Zn: 1s2 2s2 2p6 3s2 3p6 4s2 3d10
As: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3
Br: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5
Sr: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2

30. Chapter 6
Another name for the representative elements is Group A elements. Where are these elements located on the periodic table?
In the s and p sublevels
Who was the first scientist to arrange the elements according to similar chemical and physical properties in order of increasing atomic mass?
Dmitri Mendeleev

31. Chapter 6 (continued)
What is characteristic of the electron configurations of noble gases?
The highest occupied s and p sublevels are completely filled
Which subatomic particle plays the greatest role in determining the properties of an element?
electron

32. Chapter 6 (continued) What is the periodic trend for: Atomic radius
Increase Top to Bottom and Right to Left
Ionic radius
Increase Top to Bottom and Right to Left for both Cations and Anions
Ionization energy
Increase Bottom to Top and Left to Right
Electronegativity

33. Chapter 6 (continued) Na, Mg, Al, Si, S, or Cl
What is the energy required to remove an electron from an atom in the gaseous state called?
Ionization Energy
Which element would have the lowest first ionization energy?
Na, Mg, Al, Si, S, or Cl 
Which element has the largest atomic radius? H, Li, Na, K, Rb, Cs or Fr
Li, Be, B, C, N, O, or F

34. Chapter 6 (continued)
Which element has the highest electronegativity value on the periodic table?
Fluorine
Define ion, cation, and anion.
Ion: charged atom
Cation: positively charged atom
Anion: negatively charged atom

35. Chapter 6 (continued)
What are the ionic charges for the representative elements?
+1, +2, +3, +/- 4, -3, -2, -1
Write the charges for each one of these ions as a superscript
Li Ca+2
O Al+3
S Br-1
Na+1 Rb+1

36. Chapter 7 How many valence electrons would these atoms have?
Li: 1 valence electron
N: 5 valence electrons
O: 6 valence electrons
Cl: 7 valence electrons

37. Chapter 7 (continued) What is an ionic compound?
A compound composed of cations and anions
Held together by ionic bonds
What are some characteristics of ionic compounds?
Can conduct electric current when dissolved or in molten state
Has a high melting point
Crystalline solid
Brittle

38. Chapter 7 (continued)
What is the electron configurations of the following ions:
N3- 1s2 2s2 2p6
Al3+ 1s2 2s2 2p6
Cl1- 1s2 2s2 2p6 3s2 3p6
Ca2+ 1s2 2s2 2p6 3s2 3p6

39. Chapter 7 (continued) What is a metallic bond?
The attraction of metal ions to mobile electrons
What are some properties of metals?
Conductive (heat and electricity)
Malleable
Ductile
Luster
Why do metals have these properties
They have mobile valence electrons

40. Chapter 8
In a single covalent bond, how would two atoms still achieve a stable noble-gas electron configuration?
Two atoms share two electrons
How many electrons are required to create a single, double and triple covalent bond?
2 shared electrons makes a single covalent bond
4 shared electrons makes a double covalent bond
6 shared electrons makes a triple covalent bond

41. Chapter 8 (continued) What is an unshared pair of electrons
Pair of valence electrons that does not participate in bonding
According to VSEPR theory, why do molecules adjust their shapes?
to keep pairs of valence electrons as far apart as possible

42. Chapter 8 (continued)
What is a polar covalent bond? What is a non-polar covalent bond? How do you determine which type of bond would form?
Polar Covalent bonds are the result of uneven sharing of electrons
Based on the range of electronegativity values for the two atoms
Those atoms closest to Fluorine will acquire the most polar charge
Non-polar covalent bonds are the result of an even sharing of electrons

43. Chapter 8 ( continued)
Which type of solid has the strongest bond structure and therefore the highest melting point?
Ionic Solids
Metallic Solids
Network Solids