Chapter 1 Vocab (Brown-LeMay Chemistry The Central Science) Flashcards
Chemistry
The science that deals with the composition, structure, and properties of substances and with the transformations that they undergo
Matter
material substance that occupies space, has mass, and is composed predominantly of atoms consisting of protons, neutrons, and electrons, that constitutes the observable universe
Element
one of the basic substances that are made of atoms of only one kind and that cannot be separated by ordinary chemical means into simpler substances
Atom
the smallest particle of a substance that can exist by itself or be combined with other atoms to form a molecule
Property
a quality or trait belonging to a substance
Molecule
The smallest particle of a substance that retains all the properties of the substance and is composed of one or more atoms
Gas
A substance of very low density that has no definite shape or volume.
Liquid
An amorphous (non-crystalline) form of matter between a gas and a solid that has a definite volume, but no definite shape.
Solid
state of matter characterized by particles arranged such that their shape and volume are relatively stable
Mixture
an association of substances, which cannot be represented by a chemical formula
•In a heterogeneous mixture the substances are not uniformly dispersed.
•”homogeneous mixture” is loosely used to describe two or more substances that are uniformly dispersed as in a solution of water and sodium chloride (salt water).
Solution
a uniformly dispersed mixture of molecules or ions. The substance being dissolved is the solute, while the substance into which the solute is dissolved is the solvent.
Pure substance
material that is composed of only one type of particle
Compound
substance composed of atoms or ions of two or more elements that are chemically combined
Law of constant composition
Or
Law of definite proportions
all samples of a given chemical compound have the same elemental composition by mass.
Physical properties
Properties that do not change the chemical nature of matter. Examples of these are: color, smell, freezing point, boiling point, melting point, infra-red spectrum, attraction (paramagnetic) or repulsion (diamagnetic) to magnets, opacity, viscosity and density
Chemical properties
A _______ is a characteristic or behavior of a substance that may be observed when it undergoes a chemical change or reaction.
Examples of these properties of a substance can include:toxicity, oxidation, flammability, heat of combustion, enthalpy of formation, chemical stability under specific conditions, and radioactivity
Physical change
Any change that occurs without altering the chemical composition of a substance is a physical change. These can include changing the color, shape, state of matter, or volume of a substance.
Chemical change
any change that results in the formation of new chemical substances Iron rusting (iron oxide forms) Gasoline burning(water vapor and carbon dioxide forms)
Chemical reaction
process in which atoms of the same or different elements rearrange themselves to form a new substance
Intensive property
do not depend on the amount of matter, such as density and color
Extensive property
depend on the amount of matter that is being measured, such as mass and volume
Scientific method
a method or procedure consisting of systematic observation, measurement, experimentation, and the formulation, testing, and modification of hypotheses
Scientific law
statement based on repeated experimental observations that describes some aspects of the universe. Always applies under the same conditions, and implies that there is a causal relationship involving its elements.
Hypothesis
Statement that can be supported or refuted through carefully crafted experimentation or observation.
Theory
well-established explanation for scientific data
Metric system
system of weights and measures based on the meter as a unit of length, the kilogram as a unit of mass, and the liter as a unit of volume.
International System of Units(SI units)
the kilogram (kg), for mass the second (s), for time the kelvin (K), for temperature the ampere (A), for electric current the mole (mol), for the amount of a substance the candela (cd), for luminous intensity the meter (m), for distance
Mass
- The quantity of matter contained in a particle or body regardless of its location in the universe and the gravitational force applied to it.
- Mass is constant, while weight is affected by the distance of the object from the center of the earth (or other such body).
- Mass is not affected by gravity. The mass of an object is responsible for its inertia (i.e. its resistance to being accelerated).
Kelvin scale
the temperature scale used in chemistry, physics and some engineering calculations. Zero degrees Kelvin (-273 centigrade) is the temperature at which all thermal motion ceases
Celsius scale
The scale for measuring temperature used internationally where the freezing point of water is zero and the boiling point of water at sea level is 100 degrees
Density
The ratio of mass to unit volume expressed in grams/cm^3 for solids and liquids and grams/liter in gases (density=mass/volume).
Precision
In measurement indicates a set of measurements that are very similar. They may or may not be close to the true answer.
Accuracy
In measurement indicates that a set of measurements are close to the true answer, though they are not necessarily precise.
Significant figure
any digit of a number that is known with certainty; any digit of a number beginning with the leftmost non-zero digit and ending with the rightmost non-zero digit
Dimensional analysis
Dimensional Analysis is a way chemists and other scientists convert units of measurement. We can convert any unit to another unit of the same dimension. This means we can convert some number of seconds into another unit of time, such as minutes, because we know that there are always 60 seconds in one minute
Conversion factor
a numerical ratio to express a measurement from one unit to another unit in the same dimension.
To change a time measurement from hours to days, a ______ of 1 day = 24 hours.
Change of state
The physical process where matter moves from one state to another. Examples of such changes are melting, evaporation, boiling, condensation, freezing, crystallization, and sublimation.
