regents concepts and skills Flashcards
matter is classified as
a pure substance or as a mixture of substances
three phases of matter
solid, liquid, gas
structure shows phase
a pure substance
has a constant composition and constant properties
elements cannot be
broken down by chemical change
mixtures can be
separated by physical means
when different substances are mixed
a homogenous or heterogeneous mixture is formed
proportions of a mixture can be varied, but
each component retains its original properties
different properties of substances…
permit physical separation of the components
forms of energy
chemical, electrical, electromagnetic, thermal, mechanical, nuclear
physical change results in
rearrangement of existing particles in a substance with the same properties
chemical change results in
formation of different substances with changed properties
the modern model of the atom
has evolved over a long period of time through the work of many scientists
each atom has a
nucleus with an overall positive charge surrounded by one or more negatively charged electrons
subatomic particles in the nucleus are
neutrons (n) and protons (+)
proton
positive
neutron
neutral
electron
negative
number of protons equals
number of electrons in an atom
protons and neutrons are
about equal in mass
electrons are (mass)
smaller than protons/neutrons
isotopes
same number of protons, but different number of neutrons
atomic number
number of protons
identifies element
mass number
sum of protons and neutrons
identifies an isotope
when an atom gains electrons
it becomes negative
when an atom loses electrons
it becomes positive
chemical compound can be represented by
a specific chemical formula and assigned name based on the IUPAC system
types of chemical formulas
empirical
molecular
structural
in all chemical reactions there is a conservation of
mass, energy, and charge
types of reactions include
synthesis, decomposition, single-replacement, double-replacement
the mass of each proton and each neutron
is appx. equal to one amu (atomic mass unit)
mass of an atom is very nearly qual to
its mass number
the average atomic mass of an element is
the weighted average of the masses of naturally occurring isotopes
empirical formula is
the simplest whole number ratio of atoms in an element
empirical formula is different from
the molecular formula (actual ratio of atoms in a molecule of that compound)
formula mass of a substance
sum of the atomic masses of it’s atoms
molar mass (gram formula mass)
the mass of one mole of that substance
one mole
avogadro’s number
6.02 x 10^23
percent composition by mass of each element in a compound
can be calculated mathematically
a balanced chemical equation represents
conservation of atoms
coefficients in a balanced chem equation can be used to determine
mole ratios in reaction
heat is a transfer of energy from
a body of higher temp to a body of lower temp
thermal energy is associated with
the random motion of atoms and molecules
chemical and physical reactions can be
exothermic or endothermic
energy released or absorbed is equal to
the difference between potential energy of products and potential energy of reactants
energy released or absorbed by a chemical reaction can be represented by
a potential energy diagram
entropy
a measure of randomness or disorder of a system
greater entropy
greater disorder
systems in nature tend to undergo changes toward
lower energy, higher entropy
temperature is the measurement of
average kinetic energy of the particles in a gas
temperature is not
a form of energy
the concept of an ideal gas
a model to explain the behavior of gases
a real gas is most like an ideal gas when
the real gas is at low pressure and high temperature
kinetic molecular theory (KMT) for an ideal gas is that the particles are/have
in random, constant straight-line motion
separated by great distances relative to size
no attractive forces between them
collisions that may result in the transfer of energy between particles (but total energy of system remains the same)
kinetic molar theory describes
relationships of pressure, volume, temperature, velocity, and frequency
equal volumes of different gases at the same temp and pressure contain
equal numbers of particles
concepts of kinetic and potential energy can be used to explain
processes such as fusion (melting), solidification (freezing), vaporization (boiling, evaporation), condensation, sublimation, deposition
stability of an isotope
ratio of neutrons and protons in nucleus