Ch. 1 Flashcards
What is “matter”?
The physical matter of the universe. It has mass, occupies space, has properties that distinguish it, and is made up of different combinations of only a relatively small # of elements. The fundamental building block of matter is atoms.
How many significant figures should be listed in the answer when the calculation performed involves either multiplication or division?
The answer should have the same # of significant figures as the the least significant # used in the calculation. E.g. 3.45/1.2 = 2.875 = 2.9 (because 1.2 has only 2 sf while 3.45 has 3, so the answer should have 2 sf).
How many significant figures should be listed in the answer when the calculation performed involves either addition or subtraction?
The answer should have the same # of decimal places as the measurement with the fewest decimal places used in the calculation (i.e. sf doesn’t matter here, but decimal places do!). 1.234 + 2.3 = 1.534 = 1.5 (because 2.3 occupies the tenths place while 1.234 occupies the thousandths place).
Define “precision”
How close several measurements are to each other (“good grouping”, but not necessarily in the right place/accurate).
Define “accuracy”
How close measurements are to the TRUE value.
What is the calculation for density?
d= m/v
Density = mass/volume
Often measured as g/cm^3 or g/mL.
What is “volume”?
An amount of space a substance takes up. Measured by lengthlengthlength, or length^3.
Commonly measured in cm^3 or “cc” which stands for “centimeters cubed”.
What is the difference between a cc and a mL?
Both are equivalent and used to measure volume but cc’s are usually used to measure solids while mL’s are used to measure fluids.
What is “density”?
The amount of mass per unit.
(Density = mass/volume)
Often measured as g/cm^3 or g/mL.
What is an atom?
Atoms make up matter, are made of subatomic particles, and when combined form molecules.
What is an element?
A substance made purely of one type of atom.
What is the difference between a solid, a liquid, and a gas?
Solid: Has a definite shape AND volume.
Liquid: Has a definite volume. Takes the shape of the container it is in.
Gas: Compressible (no definite volume) and takes the shape of the container it is in.
What is a pure substance?
A classification of matter.
Composition doesn’t vary from sample to sample.
What is an element?
A classification of matter.
Cannot be decomposed into simpler substances. Organized into periodic table of elements.
What is a compound?
A classification of matter.
A combination of two or more ELEMENTS into distinct (unchanging, definite) proportions. E.g. CO2 will always be 1 carbon and 2 oxygen.
What is a molecule?
A classification of matter.
Two or more ATOMS.
(All compounds are molecules, but not all molecules are compounds!)
What is a mixture?
Two or more components that do not have definite proportions E.g. saltwater or a bag of mixed nuts - you know it’s a combination, but saltwater could be used to describe 1 tsp salt to 1mL of water or 1 tsp salt to 1 L of water).
What are the two types of mixtures and how are they defined?
Mixtures are two or more components that do not have definite proportions.
Homogenous Mixtures - Are uniform throughout and often called solutions.
Heterogenous Mixtures - Vary through the sample. Not really a common thing in chemistry. E.g. is a bag of nuts or a wax candle with flower pieces inside. You can pick out the parts you want, so it’s not consistent throughout.
What is a solution?
A solution is a homogenous mixtures (the two terms are interchangeable). It is a mixture of of two or more components that do not have definite proportions.
What is the difference between physical and chemical properties of matter?
Physical properties are measurable without changing the identity of the compound/substance. E.g. color, odor, melting point, boiling point (both involve changing state only), and density.
Chemical properties - describe chemical reactivity of a substance, and in order to measure these properties, we have to change the substance into another substance. E.g. Burning something requires oxygen to create a chemical reaction and the loss of electrons. Iron rusting is another example.
How are physical changes different from chemical changes?
Physical changes alter the physical appearance of something but do not change its chemical composition (e.g. boiling/melting is a state change, but the chemical bonds are not broken, therefore the compounds/molecules/substance remains the same).
Chemical changes are REACTIONS, they transform the substance into a NEW substance (e.g. rusting).
What are intensive properties?
(Inherent) properties - i.e. They do not depend on the amount of a substance in order to be expressed. They can, to some extent, be used to identify the substance. E.g. include boiling point, melting point, and density.
What are extensive properties?
Properties that depend upon the amount o a substance and cannot really be used to identify it (e.g. mass, heat evolved/required).
What is the formula for converting from degrees Fahrenheit to degrees Celsius?
C = 5/9 (F-32)
What is the formula for converting from degrees Celsius to Kelvin?
K = C + 273.15
At what temperature does water freeze in Fahrenheit, Celsius, and Kelvin?
32 F
0 C
273.15 K
At what temperature does water boil in Fahrenheit, Celsius, and Kelvin?
212F
100C
373.15 K
What is “room temperature” in Fahrenheit, Celsius, and Kelvin?
75 F
25 C
298.15 K
What is average “body temperature” in Fahrenheit, Celsius, and Kelvin?
98.6 F
37 C
310.15 K
What is the Atomic Theory of Matter?
- Elements are composed of atoms
- Atoms of an element are identical to one another but different from atoms of other elements
- Atoms of one element cannot be changed into atoms of another element (by any chemical means).
- Atoms cannot be created or destroyed in reactions (Law of Conservation of mass/matter)
- Compounds are combinations of two or more different types of elements; must have the same relative # and type of atoms (Law of Constant Composition).
Who invented the Atomic Theory of Matter?
John Dalton
What is the Law of Conservation of Mass/Matter?
Atoms cannot be created or destroyed in reactions