unit one definitions Flashcards
chemistry
field of science that examines the properties and behavior of matter, as well as the change of matter
what is the scientific method
the path that leads from experiments, hypotheses, and observations into theories or laws
what is the pathway of the scientific method?
questions/observations -> hypothesis -> experimental tests -> repeatable results that either support or refute the hypothesis
observation
something you notice in nature or an experiment
hypothesis
a tentative explanation or prediction based on observations. MUST be falsifiable to be considered scientific
experiment
carried out to test a hypothesis
Theory (model)
a set of assumptions put forth to EXPLAIN some aspect of observed behavior.
why/how
law
concise statement or summary of generally observed behavior that is always the same under the same conditions.
describing WHAT will occur
law vs theory
a law is a summary of what happens.
a theory is an attempt to explain WHY it happens
matter
anything that has mass and takes up space
solid
rigid, fixed volume and shape, slightly compressible.
solid particles have some energy which causes them to vibrate back-and-forth however, they rarely move past neighboring particles
liquid
definite volume, no definite shape (assumes shape of container), slightly compressible.
particles are arranged randomly and can FLOW past each other
gas
no fix volume or shape (assumes volume and shape of container), highly compressible
particles fly around, colliding with one another and the walls of the container
gas
no fix volume or shape (assumes volume and shape of container), highly compressible
particles fly around, colliding with one another and the walls of the container
Qualitative examples
color, smell, appearance, etc.
quantitative examples
volume, speed, time, mass
pure substance
a substance with a constant composition (ex. water, sugar, etc)
can further be broken down into compounds and elements
compound
two or more DIFFERENT atoms joined together by chemical bonds in fixed ratios
(ex H2O, CaCO3, LiCl, etc)
Elements
substance that cannot be further broken down into anything simpler, composed of a single type of atom
(ex. He, Ni, Mg, etc.)
what are the diatonics
H2, N2, O2, F2, Cl2, Br2, I2,
(should also know P4 and S8)
molecules
two or more atoms (can be the same or different) held together by chemical bonds
molecules vs compounds
molecule: two or more of the same type of element
compound: two or more different types of elements
Mixture
consists of two or more pure substances that have variable composition and can be separated by physical techniques
(ex. wood, gasoline, soil, etc.)
there are two types of mixtures
homogeneous mixture
(aka solutions)
having visibly indistinguishable parts.
two or more substances in the same phase, evenly distributed, constant composition
(ex. Saltwater)
Heterogeneous mixture
having visibly distinguishable parts. components are unevenly distributed and there is not a constant composition throughout
(ex. sweet tea and ice)
know the difference between pure substances and homogeneous mixtures
Distillation
A method of separation that depends on the boiling points of a liquid mixture to separate them
this is a good option when the components of the mixture have different boiling points
Filtration
simple method of separating a solid and liquid. The mixture is passed through a mesh, allowing the liquid to pass, leaving behind the solid.
chromatography
method to separate a liquid or gaseous phase.
Law of conservation of mass
mass is neither created nor destroyed
Law of conservation of mass
mass is neither created nor destroyed
law of definite proportion (or constant composition)
A given compound always contains the same proportion of elements by mass
extensive property
A property that depends on the amount of matter in a sample
(ex. mass, volume, length)
Intensive property
A property that is independent on the amount of matter in a sample
(ex. Color, density, boiling point, melting point, molar mass)
Density
The mass of a substance per unit of
volume
d = mass/volume
Physical change
change in the form of a substance (state or size/shape), but not an actual chemical composition
Physical change examples
ice, melting, water boiling off, cutting a sheet of paper
Chemical change
Changing the chemical composition of a substance
Chemical change examples
Iron rusting, woodburning, baking, a cake, removing carbon from carbon dioxide, lighting a match
Kinetic molecular theory of matter
as matter gains energy, it’s temperature increases. As temperature increases the average kinetic energy of the particles also increases. As the kinetic energy increases matter, transforms from solid, two liquid, to gas.
which state of matter has the most kinetic energy? Which has the least?
The gas phase has the most kinetic energy and solid has the least
Energy
The capacity to do work or transfer heat
Kinetic energy
energy because of motion, dependent on the mass and velocity of an object
Thermal energy
The form of kinetic energy associated with heat in matter
potential energy
Energy due to position in space or composition. The energy stored in chemical bonds is a type of potential energy.
accuracy vs precision
accuracy: the true value
precision: involves several measurements and how similar they are. Looks at reproducibility
accuracy vs precision
accuracy: the true value
precision: involves several measurements and how similar they are. Looks at reproducibility
what is an isotopes
Isotopes are versions of a particular element that have different numbers of neutrons
ions
Ions are atoms (or molecules) that have lost or gained electrons and have an electrical charge.
