lecture 1 Flashcards
How do scientists know that it is extraterrestrial glycine and not contamination from Earth?
They measured the atomic isotopes contained in the sample.
Law of Conservation of Mass
the total mass remains constant during a chemical reaction
A _______is a tentative explanation of some regularity of nature
hypothesis
If a hypothesis successfully passes many tests, it becomes known as a
thoery
a theory is
a tested explanation of basic natural phenomena.
two principal ways of classifying matter: are
its physical state and chemical constitution
physical states are
Solid
Liquid
Gas
chemical constitution is
Element
Compound
Mixture
solid form of matter characterized by rigidity; a solid is relatively _________ and has a fixed _____&______
incompressible,shape and volume.
liquid matter that is a relatively ________ fluid; liquid has a fixed_____ but no fixed _____
incompressible, volume, shape.
Gas matter that is an easily _____ fluid; a given quantity of gas will fit into a ______
compressible, container of almost any size or shape.
Intensive Properties
Are independent of the amount of the substance that is present.
Density, boiling point, color, etc.
Extensive Properties
Depend upon the amount of the substance present.
Mass, volume, energy, etc.
Physical Changes
in matter that do not change the______ of a substance. examples
composition ,state, temperature, volume
Chemical changes result in _______ _____ and are usually ________ , examples
new substances, irreversible Combustion, oxidation, decomposition,
A physical property is a
characteristic that can be observed for a material without changing its chemical identity.
examples of physical property
are physical state (solid, liquid,or gas), melting point, color, etc.
A chemical property is
characteristic of a material involving its chemical change.
examples of chemical property
corrosiveness).
Flammability,reactivity with acid,
An element is
a substance that cannot be decomposed by any chemical reaction into simpler substances.
The smallest unit of an element
is the atom.
A compound is a
substance composed of two or more elements chemically combined.
The smallest unit of a compound is the
molecule.
law of definite proportions states
that a pure compound, whatever its source, always contains definite or constant proportions of the elements by mass.
A mixture is a material that
can be separated by physical means into two or more substances.
Unlike a pure compound, a mixture has _____ ______
variable composition.
Mixtures are classified as:
2 way
heterogeneous, homogeneous
heterogeneous mixtures consist of
physically distinct parts (such as a mixture of sugar and salt crystals)
homogeneous mixtures are
when the properties are uniform throughout (such as sodium chloride dissolved in water)
Homogenous mixtures are often called
solutions
