Chapter 1 - Matter and Measurement Flashcards
What is Chemistry?
- The scientific study of matter, its properties, its
interactions with other matter and with energy - Chemistry comprises everything in the universe
except for the space in a vacuum
What is a law in chemistry?
A law, which has no exceptions, describes some aspect of the natural world
What is a theory in chemistry?
Theories explain observations and laws. A theory that is not 100% correct can still be useful
What are the three main states of matter?
The three classical states are solid, liquid and gas
What are some non-classical states matter can exist in?
Glass, plasma, liquid crystal and supercritical fluids
What is a pure substance?
A substance that has constant compositions
What is an element?
A substance that cannot be decomposed chemically into simpler substances
What is a compound?
A substance that can be broken down into elements
What is a homogeneous mixture?
A substance that has a visibly distinguishable parts, also known as a solution
What is a heterogeneous mixture?
A substance where you can see the components, which can be separated
What is a physical change?
A change in the form of a substance, but not its chemical composition
What is a chemical change?
A substance that becomes a new substance(s) with a different chemical composition and properties
What are the most common SI Base Units?
Length = Meter = m
Mass = Kilogram = kg
Time = Second = s
Temperature = Kelvin = K
Amount of substance = Mole = mol
What are the most common Metric prefixes?
Mega- M - 10^6
Kilo - k - 10^3
Deci - d - 10^-1
Centi - c - 10^-2
Milli - m - 10^-3
Micro - u - 10^-6
Nano - n - 10^-9
Pico - p - 10^-12
What are the equations used for temperature conversions?
Tk = Tc + 273.15
Tc = Tk - 273.15
Tf = Tc (9/5) + 32
Tc = (Tf - 32) (5/9)
What is a derived unit?
Metric units that are combinations of base units
What is volume?
The amount of space something occupies, the most common derived unit
What is density?
- Another common derived unit
- Density = mass per unit volume
- Often seen in g/cm^3 or g/mL
What are sig figs?
- All the certain digits and the first uncertain digit
of a measurement - Indicate precision in a measurement or
experiment
How do you count sig figs?
- Non-zeros are always significant
- There are three types of zeros
- Leading zeros are not significant
- Captive zeros are always significant
- Trailing zeros are significant if the number has
a decimal point
- Exact numbers have no effect on the number of
significant numbers
What is an exact number?
Units that can’t be measured
- Counted objects
- Defined amounts
- Formula numbers
- Etc.
How do you decide sig figs when using addition and subtraction?
- The result has the same number of decimal
places as the least precise measurement used in
the calculation - It’s possible to gain sig figs by addition and to lose them by subtraction
How do you decide sig figs when using multiplication and division?
The result has the same number of significant figures as the least precise measurement used in the calculation
How do you decide sig figs when doing combined calculations?
- In a series of calculations, don’t round (to adjust
the significant figures) until the end - For different kinds of operations, evaluate the
sig figs in the intermediate answer then do the
remaining steps
What is accuracy?
How close a particular value is to the true or accepted value
What is precision?
Reproducibility, how close several measurements are to each other
What are conversion factors?
Relationships between two different units
- multiplying by a conversion factor is like
multiplying by 1
- arrange conversion factors so the given unit
cancels to the desired unit
- combine as many conversion factors as
necessary, but all units must cancel except the
desired unit
