chemistry

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High School Chemistry - Core Concept Cheat Sheet
01: Introduction to Chemistry
Key Chemistry Terms
• Metric System: System of measurement based on
multiples of 10.
• SI System: Systeme International d’Unites (International
system of units).
• Meniscus: Curved appearance at the top of liquids in
containers due to the attraction between the liquid and the
container.
• Uncertainty: The last digit in a measurement is
uncertain—each person may see it slightly differently when
reading the measurement.
• Significant Figures: Digits that were actually measured
and have physical significance. Also called “significant
digits”.
Metric System
The metric system uses prefixes to indicate multiples of 10
Metric Prefixes commonly used in chemistry
Prefix Symbol Multiple
Kilo k 1000
Deci d 0.1
Centi c 0.01
Milli m 0.001
Micro μ 0.000001
Nano n 0.000000001
The “base unit” is when there’s no prefix.
To determine the equivalent in “base units”:
1. Use prefix to determine multiple.
2. Multiply number by the multiple.
3. Write the result with the base unit.
Examples:
1.25 mL “milli” means 0.001 0.00125 L
87.5 kg “kilo” means 1000 87500 g
SI System
The SI system gives the fundamental unit for each type of
measurement.
SI Units commonly used in chemistry
Measurement Unit Symbol
Mass Kilogram kg
Volume Liter L
Temperature Kelvin K
Length Meters m
Time Seconds s
Amount of
substance
Mole Mol
Energy Joule J
Charge Coulomb C
Non-SI Units commonly used in chemistry
Measurement Unit Symbol
Length Angstrom Å
Pressure Atmosphere Atm
Kilopascal kPa
Energy Calorie cal
Temperature Celsius °C
Measurements & Uncertainty
Most commonly used instruments for
measurements in chemistry
Quantity Instrument
Mass Balance
Volume Graduated cylinder
Temperature Thermometer
Measurement & Uncertainty (Cont.)
• When measuring volumes, always read from the bottom of
the meniscus.
• When recording measurements, record 1 more decimal place
than the “lines” give you.
o Record a “0” at the end if it is on the line
o Record a “5” at the end if it is in-between lines
• Zero’s at the end of a reading are important—they indicate
that it was “on the line”.
Examples:
reading: 4.35 mL reading: 25.0 mL
• The last digit recorded is always assumed to be uncertain.
• The uncertainty is assumed to be +/- 1 unless otherwise
stated.
Examples:
A reading
of…
Is assumed to be
between…
10.05 mL 10.04 mL & 10.06 mL
10.0 mL 9.9 mL & 10.1 mL
10 mL 9 mL & 11 mL
Significant Figures
Significant figure rules are used so that everyone that reads
data or results understands to what precision data was
recorded.
Only figures that were actually measured are significant.
Summary of rules for counting significant figures:
1. If there is a decimal point anywhere in the
number: Start with the first non-zero number and
count all digits until the end.
2. If there is not a decimal point in the number:
Start with the first non-zero number and count
until the last non-zero number
Examples:
10.020 g Rule #1 10.020 5 significant figures
0.00240 L Rule #1 0.00240 3 significant figures
1250 mL Rule #2 1250 3 significant figures
10200 mg Rule #2 10200 3 significant figures
How to Study Chemistry
• Memorize basic information to speed up problem-solving
later.
• Try to learn vocabulary quickly so you’re familiar with it
when you see it.
• Brush up on algebra—don’t try to memorize every variation
of an equation!
• Look for commonalities between different problems—many
different types of problems are similar than they appear.
• Break each problem down into steps—always identify the
given information and where you’re headed.
• Try to understand why behavior occurs & look for patterns.
• Connect new concepts to previously learned concepts.
• Keep up with the work—don’t let yourself fall behind.
• Ask for help when you need it!