Chapter 1 Flashcards
Matter, Energy, and Measurement
What is chemistry?
the study of matter, its properties, and the changes it undergoes
What is matter?
anything that has mass and takes up space; 3 states: solid, liquid, gas
What is a substance?
a substance has distinct properties and a composition that does not vary from sample to sample; 2 types: element, compound
What is an element?
a substance that can NOT be decomposed to simpler substances; made up of a unique kind of atom, but can be made of more than one atom of that kind
What is a compound?
a substance that CAN be decomposed to simpler substances because it is made up of more than one element; made of atoms from two or more elements
What are atoms?
the building blocks of matter
What are molecules?
groups of atoms
What is the Law of Constant Composition?
states that compounds have a definite composition, meaning the relative number of atoms of each element in the compound is the same in any sample
What is a heterogenous mixture?
a mixture that can VARY in composition throughout a sample
What is a homogenous mixture?
a mixture with the same composition throughout the sample; EVENLY MIXED; aka a solution
What are physical properties?
properties that can be observed WITHOUT CHANGING a substance into another substance (ex. color, odor, density, melting and boiling points, hardness)
What are chemical properties?
properties that can only be observed when a substance is CHANGED into another substance (common ex. flammability - ability to burn in oxygen, a form of reactivity)
What are intensive properties?
properties that are independent of the amount of the substance that is present (ex. density, boiling point, color); important for identifying a substance
What are extensive properties?
properties that depend on the amount of the substance present (ex. mass, volume, energy)
What are physical changes?
changes in matter that do NOT change the composition of a substance (ex. changes of state, temperature, and volume)
What are chemical changes?
changes that result in new substances (ex. combustion, oxidation, decomposition)
How can mixtures be separated?
based on physical properties of the components of the mixture; filtration, distillation, chromatography
What is filtration?
solid substances are separated from liquids and solutions; based on different phases
What is distillation?
uses differences in boiling points of substances to separate a homogenous mixture into its components; based on different boiling points
What is chromatography?
separates substances on the basis of differences in the ability of substances to adhere to the solid surface; based on ability to adhere to a stationary phase
What is energy?
capacity to do work or transfer heat
What is work?
energy transferred when a force exerted on an object causes a displacement of that object
What is heat?
the energy used to cause the temperature of an object to increase
What is force?
any push or pull on an object
What is kinetic energy?
the energy of motion
What is potential energy?
stored energy; potential energy of an object depends on its relative position compared to other objects
What are six basic types of energy?
chemical
heat
electrical
mechanical
light
nuclear
What are the SI units (International System of Units)?
length - meter (m)
mass - gram (g)
temperature - Kelvin (K) or degrees Celsius
time - second (s)
amount of a substance - mole (mol) 6.022x10^(23) things
volume - cubic centimeter (cc, cm^3, or mL) or liter (L)
What are these prefixes: mega, kilo, centi, milli, micro, nano?
mega - 1x10^6 - 1,000,000
kilo - 1x10^3 - 1000
centi - 1x10^-2 - 0.01
milli - 1x10^-3 - 0.001
micro - 1x10^-6 - 0.000001
nano - 1x10^-9 - 0.000000001
What is the freezing point, boiling point, and density of water?
freezing point - 0 C / 32 F / 273 K
boiling point - 100 C / 212 F / 373 K
density - 1 g/mL
How do you convert kelvin to Celsius?
K = C + 273
How do you convert Celsius to Fahrenheit?
F = 9/5 C + 32
What is the unit of energy?
Joule (J)
What is an exact number?
a number that is counted or given by definition (12 eggs in 1 dozen)
What is an inexact number?
a number that depends on how it was determined; scientific instruments have limitations and individuals can read some instrumentation differently; aka measured number
What is precision?
a measurement of how closely individual measurements agree with one another
What is accuracy?
a measurement of how closely individual measurements agree with the correct, or “true”, value
What figures are significant?
- all nonzero digits
- zeroes between nonzero digits
- zeroes at the beginning of a number are NEVER significant
- zeroes at the end of a number are significant if it contains a decimal point
How do you use significant figures in calculations?
+/- answers are rounded to least significant decimal place
multiplication/division answers rounded to same number of digits as the measurement with the fewest number of significant figures
