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
most nuclei are stable, but
some are unstable and decay spontaneously, editing radiation
each radioactive isotope has
a specific mode and rate of decay
transmutation
a change in the nucleus of an atom that converts the atom to another
transmutation can occur
naturally or can be induced by bombarding the nucleus with high-energy particles
spontaneous decay can involve the release of
alpha particles
beta particles
positrons
gamma radiation
different emissions differ in
mass, charge, ionizing power, penetrating power
nuclear reactions include
natural transmutation
artificial transmutation
fission
fusion
both benefits and risks are associated with
fission and fusion reactions
nuclear reaction can be represented by equations that include
symbols that represent atomic nuclei
subatomic particles
emissions such as alpha, beta, gamma
the energy released in a nuclear reaction (fission or fusion) comes from
the fractional amount of mass converted into energy
the energy released during nuclear reaction is much greater than
the energy released during chemical reactions
risks with the use of radioactive isotopes
biological exposure
longterm storage and disposal
mutations
nuclear accidents
benefits of radioactive isotopes (in research, medicine, and industry)
radioactive dating tracing chemical/biological processes industrial measurements nuclear power detection and treatment of disease (such as cancer)
each electron in an atom has its own
distinct amount of energy
when an electron gains a specific amount of energy it is in the
excited state
electron going from higher to lower energy state
energy is emitted (can identify the element)
electron orbitals
ground state
most probable electron location
valence electrons
the outer most electrons
valence electrons affect
chemical properties of the element
lewis dot structure
shows valence electrons
placement on periodic table
indicate physical and chemical properties
elements on table are arranged in
increasing atomic number
elements can be classified by their properties, such as
metals, nonmetals, metalloids (B, Si, Ge, As, Sb), noble gases
elements can be differentiated by physical properties, such as
density, conductivity, malleability, solubility, and hardness
elements can be differentiated by heir chemical properties by
how they act in a chemical reaction
groups 1, 2, and 13-18
each group has same # of valence electrons
have similar properties, but not helium
as the elements go down in groups
atomic radius increases
electronegativity decreases
first ionization energy decreases
metallic properties decrease
when atom gains 1+ electrons
radius increases
becomes more negative
when an atom loses 1+ electrons
radius decreases
becomes more positive
degree of polarity is determined by
electronegativity difference between two bonded atoms
when a bond is broken
energy is absorbed
when a bond is formed
energy is released
atoms attain a stable valence electron configuration by
bonding with another atom
noble gases have
stable valence electron configurations and generally do not bond
major categories of compounds
ionic
molecular
chemical bonds are formed when valence electrons
transfer from one atom to another (ionic)
share between atoms (covalent)
mobile within a metal (metallic)
electronegativity indicates
how strongly an atom attracts electrons in a chemical bond
electronegativity values are assigned
according to arbitrary scales
metals tend to react with
nonmetals to form ionic
nonmetals tend to react with
other nonmetals to form molecular (covalent) compounds
ionic compounds containing polyatomic ions have
both ionic and covalent bonding
intermolecular forces created by an unequal distribution of charge result in
varying degrees of attraction between molecules
the polarity of a molecule is determined by the
shape of the molecule and the distribution of charge around
symmetrical molecules
nonpolar
asymmetrical molecules
polar
diatomics
H, N, F, O, I, Cl, Br
hydrogen bonding is
a strong intermolecular force
organic compounds contain
carbon atoms that bond to one another
how to name compounds
IUPAC
hydrocarbons
hydrogen and carbon only
saturated hydrocarbons
only single carbon-carbon bonds
unsaturated hydrocarbons
at least one multiple carbon-carbon bond
categories of organic compounds
organic acid alcohol esters aldehydes ketones ethers halides amines amides amino acid
types of organic reactions
addition substitution polymerization esterification fermentation saponification combustion
isomers of organic acids
have the same molecular formula, but different structures and properties
a solution is a
homogenous mixture
solubility is dependent on
temperature, pressure, chemical natures of solute and solvent
concentration can be expressed as
molarity
percent by mass
parts per million
salt
freezing point decreases
boiling point increases
greater concentration
the greater the effect
electrolyte
releases mobile ions in aq solution
allows solution to conduct electricity
rate of chemical reaction depends on
temp concentration nature of reactants surface area presence of a catalyst
Le Châtelier’s principle is used to
predict effects of stress on a system at equilibrium
catalyst provides
alternative reaction pathway that has lower activation energy
collision theory
a reaction is most likely to occur if reactants of particles collide w/ proper energy and orientation
some chemical and physical changes can reach
equilibrium
at equilibrium the rate of forward reaction equals
the rate of reverse reaction
the measurable quantities at equilibrium
remain constant
acidity or alkalinity are measured by
pH level
on the pH scale, each decrease of one unit of pH represents
a tenfold increase in hydronium ion concentration
in the process of neutralization, an arrhenius base and an arrhenius aside react to form
salt and water
arrhenius bases yield
hydroxide ions as the only negative ions in an aq solution
arrhenius acids yield
hydrogen ions as the only positive ions in an aq solution
arrhenius bases and acids are
electrolytes
titration
lab process to determine concentration of an unknown
voltaic cells
spontaneously coverts chem. energy to elect. energy
electrolytic cells
require elec. energy to produce chem. change
electrolysis
redox reaction involves
transfer of electrons
reduction
gain of electrons
half-reaction can be written
to represent reduction
to represent oxidation
oxidation
loss of electrons
in a redox reaction
of electrons lost = # of electrons gained
oxidation states can be assigned to
atoms or ions
change in oxidation # indicates
that oxidation or reduction has occurred
an electrochemical cell can be
voltaic of electrolytic
in electrochemical cell
oxidation occurs at the anode
reduction occurs at the cathode
