Midterm Exam Flashcards
(Vocab)
Scientific Method
Organized approach to solve a problem
What are the steps of the scientific method and explain?
Observe - Define the problem (use 5 senses)
Hypothesis - Reasonable explanations for what was observed (educated guess)
Experiments - Test each hypothesis in order to prove/disapprove them
Analysis - Compares the results from the experiments to the original hypothesis
Conclusion (Theory) - A hypothesis supported by experimental evidence
(Vocab)
Law
Used to describe a natural phenomenon which has been tested over a long period of time
(Vocab)
Theory
A hypothesis supported by experimental evidence
(Vocab)
Chemistry
The study of matter + the changes it undergoes
What is the difference between an element and a compound?
Elements = made up of one atom
compounds = made up of 2 or more diff. elements (multiple atoms)
Give examples of an element.
Hydrogen, Helium, Carbon etc. (anything on the Periodic Table)
Give examples of a compound.
CO2 (carbon dioxide), NO2 (nitrogen dioxide)
(formed when elements chemically combine)
(Vocab)
Homogeneous mixture + examples
Has a uniform composition (parts of the mixture + cannot be picked out)
Ex: milk, sugar
(Vocab)
Heterogeneous mixture + examples
Doesn’t have a uniform composition (Parts of the mixture can be physically seen + picked out)
Ex: cereal, salad, pizza
(Vocab)
Chemical changes + examples
One or more substances react to form new substances w/ diff. chemical + physical properties (The beginning substances w/ diff. than the ending substances)
Ex: rusting, burning, decaying
(Vocab)
Physical changes + examples
Changes in appearance w/o changing composition
Ex: cutting, breaking, freezing, boiling, melting
(Vocab)
Physical Properties + examples
Properties that can be measured or observed w/o changing the identity (or composition) of a substance
Ex: color, odor, texture, taste
(Vocab)
Chemical Properties + examples
Properties that indicate how a substance reacts w/ other substances.
Ex: flammable, combustible, burnable
(Vocab)
Law of Conservation of Matter/Mass
In any chemical or physical change, matter cannot be created or destroyed (mass of reactants = mass of products)
Explain the difference between accuracy and precision.
Accuracy = How close a measurement is to the true or accepted value
Precision = How close multiple measurements are to each other
Write out 3.5 x 10^-5 in long form.
0.000035
Write out 7,123 in scientific notation
7.123 x 10^3
Write out 0.000000081 in scientific notation
8.1 x 10^-8
Write out 8 x 10^8 in long form.
800,000,000
Answer (6 x 10^-8) x (4x10^-4) in proper scientific notation.
2.4 x 10^-11
Write out 453,000 in scientific notation
4.53 x 10^5
Write out 0.000157 in scientific notation
1.57 x 10^-4
Solve: 30,000 x 0.0004 in scientific form
1.2 x 10^1
Write out 2 x 10^3 in long form.
2000
Solve: (3 x 10^-8) x (7 x 10^6) in scientific notation
2.1 x 10^-1
Write out 0.0029 in scientific notation.
2.9 x 10^-3
Solve: 37,000 x 7,000 in scientific notation
2.59 x 10^8
Write out 41,000 in scientific notation.
4.1 x 10^4
Write out 60,007,000 in scientific notation.
6.0007 x 10^7
List the rules for Significant Figures
1) All non-zero digits are significant
2) Leading zeros are never significant (zeros to the left)
3) Captive zeros are always significant (zeros in the middle)
4) Trailing zeros are sometimes significant (zeros at the end)
- they are sig. if the # contains a decimal point
- they aren’t sig. if # does NOT contain a decimal point
What is the rule for Addition and Subtraction when solving an equation with sig. figs.?
the answer is rounded to the same # of decimal places as the # used in the calculation with the least decimal places.
Ex #1: 7.12 - 1.345 = 5.775 = 5.78
(7.12 has the least number of decimal places in the equation so we would round our answer 5.775 to have the same amt of decimal places. This would make the answer 5.78, which is also rounded to the nearest hundredth, DONT FORGET TO ROUND)
Ex #2: 5.7 + 2.11 = 7.81 = 7.8
What is the rule for Multiplication and Division when solving an equation with sig. figs.?
the answer is rounded to the same # of sig. figs. as the # used in the calculation with the least sig. figs.
Ex #1: 17.85/2.13 = 8.38028 = 8.38
(You divide the 2 #’s and get that long number but since 2.13 is the # with the least sig. figs. you round your answer to get the same amt of sig. figs., which is 3, this will lead you to get the answer 8.38)
Ex #2: 0.0561 x 0.030 = 0.001683 = 0.0017 (rounded)
What is Dimensional Analysis?
A method used to convert units
Solve using Dimensional Analysis, How many seconds are in 1.50 weeks?
907 s
how many sig. figs. are in the number 0.02?
1
(Vocab)
Matter
Anything that has mass + volume (everything)
How many g are equal to 345.7 mg?
0.3457
How many Micrograms (μg), Microliters (μL), and Micrometers (μm) are in grams (g), liters (L), and meters (m)?
10^-6μg = 1g
10^-6μL = 1L
10^-6μm = 1m
(Vocab)
Mass
The amount of matter in an object
how many sig. figs. are in the number 0.020?
2
Solve using Dimensional Analysis, how many feet are equal to 54.7 inches?
4.56 ft
How many Kg are equal to 45,000 mg?
0.045 kg
How many Milligrams (mg), Milliliters (mL), and Millimeters (mm) are in grams (g), liters (L), and meters (m)?
1000mg = 1g
1000mL = 1L
1000mm = 1m
Answer the equation with the correct amt of sig. figs.
16.590/1.8 = ?
9.2
how many sig. figs. are in the number 2.0x10^-3?
2
How many mins are in an hour?
60 mins.
How much feet are in a mile?
5280 feet
Mount Everest is approximately 8,000 meters high. How many miles high is Mount Everest?
5 miles
What is the symbol and meaning for the prefix micro?
Symbol: μ
Meaning: millionth (10 ^-6)
Answer the equation with the correct amt of sig. figs.
3.085 + 2.77448 = ?
1.112
Answer the equation with the correct amt of sig. figs.
3.42 + 8.132 = ?
11.55
How many hours are in a day?
24 hours
how many sig. figs. are in the number 2,002?
4
Answer the equation with the correct amt of sig. figs.
1.2 x 1.3 = ?
1.6
Answer the equation with the correct amt of sig. figs.
32.88/4.38 = ?
7.51
A homerun in a baseball game was measured at 450 ft. How many meters is this equal to?
14 meters
How many ounces are in a pound?
16 ounces
What is the symbol and meaning for the prefix Kilo?
Symbol: K
Meaning: thousand
Answer the equation with the correct amt of sig. figs.
2.16 x 1.8 = ?
3.9
how many sig. figs. are in the number 20,000?
1
Answer the equation with the correct amt of sig. figs.
4.55 + 3.45 = ?
8.00
What is the symbol and meaning for the prefix Milli?
Symbol: m
Meaning: thousandth
how many sig. figs. are in the number 20,020?
4
A chemistry student has a weight of 155 lbs. What is the student’s weight in grams? (1oz = 28.34 g)
70,300 g
What is the symbol and meaning for the prefix Centi?
Symbol: c
Meaning: hundredth (0.01)
Answer the equation with the correct amt of sig. figs.
4.3324 x 1.2 = ?
5.2
How many Decigrams (dg), Deciliters (dL), and Decimeters (dm) are in grams (g), liters (L), and meters (m)?
10dg = 1g
10dL = 1L
10dm = 1m
What is the symbol and meaning for the prefix Deci?
Symbol: d
Meaning: tenth (0.1)
how many sig. figs. are in the number 1.09x10^4?
3
How many grams (g), liters (L), and meters (m) are in Megagrams (Mg), Megaliters (ML), and Megameters (Mm)?
1Mg = 1,000,000g
1ML = 1,000,000L
1Mm = 1,000,000m
What is the symbol and meaning for the prefix Mega?
Symbol: M
Meaning: Milllion
How many centimeters are in an inch?
2.45cm
The Empire State Building is approximately 381 meters high. How many miles high is the Empire State Building?
0.237 miles
Change 0.00765 into mL
765 mL
What are the base units?
mass: in grams (g)
volume: in liters (L)
length: in meters (m)
how many sig. figs. are in the number 0.055870?
5
How many grams (g), liters (L), and meters (m) are in Kilograms (kg), Kiloliters (kL), and Kilometers (km)?
1kg = 1,000g
1kL = 1,000L
1km = 1,000m
A chemistry student’s height is measured at 68.5 inches. How tall is the student in cm?
17.4 cm
How many mm are equal to 4.75 x 10^-2 m?
47.5 mm
How many ML are equal to 4.567 x 10^4 mL?
4.567 x 10^-5 mL
How many seconds are there in 2.5 days?
21 seconds
How many Centigrams (cg), Centiliters (cL), and Centimeters (cm) are in grams (g), liters (L), and meters (m)?
100cg= 1g
100cL = 1L
100cm= 1m
How many centimeters are in a meter?
100 centimeters
How many inches are in a foot?
12 inches
(Vocab)
Pure Substances + examples
Have uniform + definite composition
Ex: Elements + Compounds
What is the difference between compounds and mixtures?
In compounds = elements are bonded to each other
In Mixtures = the substances are blended (no definite composition - cannot assign a fixed ration)
Is breaking chalk a chemical or physical change?
Physical change
Is molding clay a chemical or physical change?
Physical Change
Is buring toast physical or chemical change?
Chemical change
Is rusting iron a physical or chemical change?
Chemical change
Give an example to show a measurement that is accurate and precise.
27.00 mL
27.00 mL
27.00 mL
What are the 2 major areas that matter is classified into?
1) Pure substances
2) Mixtures
Give an example to show a measurement that is neither accurate nor precise.
31.57 mL
25.06 mL
29.72 mL
Give an example to show a measurement that is precise but not accurate.
30.00 mL
29.97 mL
30.00 mL
What was the 1st idea of the atom?
The 1st idea of atom was from the Greek philosopher, Democritus. He believed that matter was composed of tiny indivisible particles called atoms. Since it was so long ago, and they had very little technology, he had no experimental evidence to support his thoughts.
State 4 major ideas of Dalton’s Atomic Theory:
1) All elements are composed of invisible particles called atoms
2) Atoms of the same element are identical. The atoms of any one element are diff. from those of another
3) Atoms of diff. elements mix or combine in whole number ratios
4) Chemical reactions occur when atoms separate, join, or rearrange. In a chemical reaction, atoms of another element NEVER change into another.
What is the experiment that led to the discovery of the electron?
The Cathode Ray Tube Experiment led to the discovery of an atom. There was a tube with insert gas and 2 plates, a positive and a negative one. The particles in the gas were attracted to the positive plate, and therefore we conclude that the particles must have a negative charge (opposites attract)
Explain Rutherford’s gold foil experiment.
Rutherford shot a high beam of positive alpha particles into a sheet of gold foil. Some of the particles were scattered/deflected which led to the conclusion that the atom has a tiny, hard, and dense crystal at the center of the atom, called the nucleus.
What are the 3 subatomic particles, what are their charges and where are they located?
Protons: positive charge, nucleus
Neutrons: neutral, nucleus
Electrons: negative charge, in the electron cloud outside the nucleus in energy levels.
What does the atomic number represent?
The number of protons in the element
What does the mass number represent and what is the formula to find it?
The number of protons and neutrons combined
(protons + neutrons = rounded atomic mass/mass #)
What are isotopes? How are they the same? How are they different?
Isotopes are atoms with the same number of protons, but different number of neutrons. They are the same because they are all chemically alike, but the are different because they have different mass numbers.
What does the atomic mass represent?
The average (weighted) of all the element’s isotopes
What is an ion?
Atom or group that has a positive + negative charge.
What are the 2 ways in which you can form an ion?
1) When an atom gain electrons
2) When an atom loses electrons
What is density? What is the formula?
Density is the amount of mass per unit volume.
Formula: D= m/v
Calculate the atomic mass of Carbon if the two common isotopes of Carbon have masses of 12 amu (98% abundance) and 13.003 amu (1.11% abundance)
12.011 = atomic mass of Carbon
Who discovered the proton?
Eugene Goldstein
Calculate the atomic mass of sulfur if the four common isotopes of sulfur have masses
of 31.972 amu (95.00 % abundance), 32.971 amu (0.76%), 33.967 amu (4.22 %), and 35.967 amu (0.014 %).
32.05 = atomic mass of sulfur
Who discovered the neutron?
James Chadwick
Which scientist said that the atom was mostly empty space?
Ernest Rutherford
What is the formula for finding the number of neutrons?
Neutrons = mass # - atomic #
How are isotopes written?
Element - mass #
