Science and Measurement Flashcards
What is chemistry
the study of matter and energy
matter
anything that has mass and occupies space
elements
the simplest form of matter that has distinct physical and chemical properties and cannot be broken down chemically into simpler, stable substances; building blocks for everything
atom
the smallest amount of an element that still has the characteristics of that element
chemical bonds
An attraction between atoms of different elements; can be broken and re-formed
compound
a chemical combination of elements that has its own set of properties and a definite composition
The two types of pure substances:
elements and compounds
mixture
two or more pure substances physically combined; no definite composition and can be heterogeneous or homogeneous
Homogeneous mixtures
also called solutions
Which phases can solutions be found in?
gas, solid, aqueous
Element examples
Hydrogen, sodium
Compound examples
water (H2O), Table salt (NaCl)
Heterogeneous mixture examples
oil and water mixture, chicken noodle soup
homogeneous mixture examples
brass, vodka
properties
characteristics by which something can be identified
Physical Properties
describe or identify a substance w/o changing its chemical composition
Physical Properties Examples
color, melting point, conductivity
Chemical properties
characteristic chemical reactions a substance undergoes
Extensive Properties
depend on the amount of a substance present
Extensive properties examples
mass, volume
Intensive properties
properties that are the same regardless of sample size
Intensive properties Examples
density, color, melting point
Physical Change
Chemical composition is not altered; Iron and sulfur can be mixed but remain iron and sulfur. They can be separated based on their different solubilities (another physical property).
Reactant
starting material in a chemical change (reaction)
product
resulting material in a chemical change (reaction)
Chemical changes
alter the chemical structure of a substance by breaking and/or forming chemical bonds
Mass
how much matter an object has; directly proportional to weight
Energy
capacity to do work
Law of Conservation of Energy
Energy cannot be created or destroyed but can be converted from one form to another
Scientific Method
A process that combines observation, hypothesis, and experimentation
Hypotheses
the initial explanation for some observed fact(s), based on observation/evidence; are to be revised and tested through experimentation
Theories
explain and predict many different observations that are linked by the same underlying phenomena; generally widely accepted as valid explanations of phenomena
Scientific Laws
observations that are always true; statements of a phenomenon w/o explanation
Law of Conservation of Mass
in any chemical reaction or physical change, the total mass present after the change is equal to the total mass present before the change; discovered by Lavoisier; does not apply to nuclear reactions
Base Units (fundamental units)
units defined by a particular physical measurement
SI unit of length
meter, m
SI unit of mass
Kilogram, kg
SI unit of time
second, s
SI unit of temperature
Kelvin, K
SI unit for Amount of a Substance
Mole, mol
Tera-
10^12
Giga-
10^9
Mega-
10^6
Kilo-
10^3
Deci-
10^-1
Centi-
10^-2
Milli-
10^-3
Micro-
10^-6
Nano-
10^-9
Pico-
10^-12
Qualitatitve
the identity or form of a substance present
quantitative
the amount of a substance present
accuracy
the closeness of the average of a set of measurements to the true value
precision
the closeness of all of a set of measured values to one another
significant digit
every digit that reflects the precision of the measurement, including the estimated digit at the end
Density
the measure of how much mass something has relative to its volume; m/v
Three temperature scales
Fahrenheit, Celsius, Kelvin
Conversion from Fahrenheit to Celsius
C = 5/9(F-32)
F = 9/5(C+32)
Celsius to Kelvin
K= C+273.15
