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Yes, I graded your tests…
• I’m passing them back now
• Have your midterm review guide answers out. Remember, this was for homework!
MIDTERM IS TOMORROW!!!!!!
This counts 5% of your final grade!
Test 2
• The periodic table is organized bya. Increasing proton number
b. Increasing atomic mass
c. Increasing neutron number
d. alphabetically
• Which compounds are identical?– Compound A 10 g 2 mL– Compound B 40 g 8 mL– Compound C 5 g 2 mL– Compound D 40 g 5 mL
a. compounds A & B
b. compounds A & C
c. compounds B & C
d. compounds B & D
e. none are the same
• There is an unknown metal. What data could you collect to identify it?
a. Color
b. Mass
c. Density
d. temperature
Midterm Review Guide Answers
• Dependent vs Independent Variable– Independent- what we change the cause– Dependent- what changes & we observe, the effect
– Fertilizer in plant growth experiment• Independent = fertilizer dependent = plant
growth
– Time in evaporation experiment• Independent = time dependent = evaporation
– Temperature in experiment to determine the heat produced by candle waxes
• Independent = candle wax dependent = temperature
Midterm Review Guide Answers
• Lab equipment– Volume
• Graduated cylinder
– Mass• Triple beam balance
– Meniscus• Read volume
Midterm Review Answers• Significant Figures
– Groups of data go up and down– 0.89, 0.91, 0.90
1 2 3 4
Accurate? Yes Yes No No
Precise? No Yes No Yes
Midterm Review Answers• Dimensional Analysis
– 14.8 hours– 2300 grams– 34 meters– 5.8 meters
• Scientific Notation– 3.2 x 10-5
– 2.7 x 1012
Midterm Review Answers
• Physical/Chemical Change– Chemical change = iron rusting– Water displacement = volume = extensive– Color = intensive
Changes in Matter
• Evidence of chemical reaction:1. Gas is produced2. Color Change3. Change in smell4. Formation of solid—precipitate5. Light is produced6. Temperature change
-exothermic-endothermic
Midterm Review Answers
• Solids, liquids, gases– Liquid = Fixed volume, variable shape– Gas = Highest kinetic energy– Gas = Variable shape, variable volume– Solid = Particles vibrate around a central point
– Gas = Compressible– Gas = Most kinetic energy
Midterm Review Answers
• Heterogeneous / Homogeneous– Heterogeneous = looks different, not uniform– Homogeneous = looks same, uniform
– Homogeneous = Kool Aid
Midterm Review Guide
• Density– 2 g/mL– Sink b/c density is greater than 1– Aluminum has a density of 2.63 g/mL. Which
one is aluminum?• Choice 1: Mass = 427 g Volume = 175 mL
• Choice 2: Mass = 526g Volume= 200 mL
Midterm Review Answers
• Atomic Structure– Ba: 81 neutrons (81.3), 56 protons, 56 electrons– 20 amu (10 protons + 10 neutrons)– 14 neutrons (26-12)– Neutron– Rutherford found the nucleus of an atom– 1s2, 2s2, 2p6
– Electrons releasing light as they fall back to their ground state orbital
Midterm Review Answers• Isotopes
– 6 P+, 8 No, 6 e-– Neutrons
• Atomic Mass– Atomic Mass = protons + neutrons– Which would have the greatest effect on the
atomic mass?– 30 % Iron-56– 60% Iron-57– 10% Iron-59
Midterm Review Answers• Conservation of Mass
– Each side must have the same number of atoms of each element
• Electron Configuration– Sulfur– Down (up, up, up, down)– S orbital =2, p orbital = 6, d orbital = 10, f
orbital = 14– 6 valence electrons
Midterm Review Answers
• Alpha, beta, gamma– Gamma- most penetrating– Alpha- positive– Gamma – no mass, no charge– Beta - electron
He42 01 00
Midterm Review Answers• Fission/Fusion
– Nucleus split in two• Fission
– Occurs on the sun– Combining of 2 nuclei into one
• Fusion
Midterm Review Answers
• Half Life– 12.5 grams– 6 half lives
• Radioactive Waste– Nuclear waste is radioactive; the problem is
storage– No
Midterm Review Answers
• Indicators of a chemical change– Change in color– Change in temperature
• Evidence of chemical reaction:1. Gas is produced2. Color Change3. Change in smell4. Formation of solid—precipitate5. Light is produced6. Temperature change
-exothermic-endothermic
Midterm Review Answers
• Neutral Atom– 10 P+, 10 e-, 10 N0
• Kinetic/Potential Energy– Kinetic = energy of motion– Potential = stored energy– A skydiver in freefall– Gas
Midterm Review Answers
• Exothermic / Endothermic Reactions– Exothermic = energy is released– Endothermic = energy is absorbed
• Endothermic = Temperature decreases• Exothermic = Fire• Endothermic = Cold compression pack• Endothermic = Ice melting
Midterm Review Answers
• Dependent / Independent Variables– Fertilizer or growth rate of plants
• Independent = fertilizer• Dependent = growth rate
– Increase in heat or speed of molecules• Independent = increase in heat• Dependent = speed of molecules
Midterm Review Answers• Periodic Table
– Solid– Families are vertical– 4 energy levels– 6 valence electrons
Bingo!• Put the following words on your Bingo card
Isotope Gamma Alpha Chemical Physical
Half life Proton Gas Float Density
Homogeneous
Fusion Fission Endothermic Liquid
8 14 6 Precision Solid
Neutron Electron Increase Decrease Free space
• Type of radiation that is made of a helium particle and can be stopped with paper
a. alpha
b. beta
c. gamma
• Density of water is 1.0 g/mL
• Which set of data would be precise but not accurate?
a. 1.22, 1.70, 0.82
b. 0.85, 0.87, 0.86
c. 1.01, 1.00, 1.03
• When an object has a density of less than 1 g/mL, we know the object will ________ in water
a. sink
b. float
• Nuclei are radioactive when they become unstable due to the ratio of neutrons to
a. protons
b. electrons
• Subatomic particle that is outside the nucleus and carries a negative charge
a. proton
b. neutron
c. electron
• Atoms with the same number of protons but a different number of neutrons
a. half life
b. isotope
c. element