CHEMISTRY VOCAB

Atomic Radius
one half the distance between the nuclei of two atoms of the same element when they are joined
non metals
poor conductors of heat and electricity
periodic law
when elements are arranged in order of increasing atomic # there is periodic repetition of physical and chemical properties
halogens
elements found in group 7A
transition metals
elements with s and d orbitals of the highest occupied energy level containing electrons
cation
ion with a positive charge
ionization energy
energy required to remove an electron from an atom
electronegavity
the ability of an atom of an element to attract electrons when the atom is in a compound
anion
ion with negative charge
base
an ionic compound that produces hydroxide ions when dissolved in water
binary compound
composed of two elements and can be either ionic or molecular
law of definite proportions
in samples of any chemical compound, masses of elements are always in same proportions
acid
compound that contains one or more hydrogen atoms and produces hydrogen ions when dissolved in water
polyatomic ion
ions composed of more than one atom
law of multiple proportions
whenever the same two elements form more tahn one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole #’s
monatomic ions
ions consisting of a single atom
matter
anything that has a mass and occupies space
technology
which society….
biotechnology
applies science to the production of biological products or processes
pollutant
material found in air, water, or soul that is harmful to humans etc
scientific method
scientific approach to the solution of a scientific problem
observation
using your senses to obtain info
experiment
procedure that is used to test a hypothesis
manipulated variable
variable that you change during experiment
responding variable
variable that is observed during the experiment
theory
well-tested explanation for a broad range of observations
scientific law
concise statement that summarizes the results of many observations and experiments
mass
measure of the amount of matter the object contains
volume
measure of space occupied by the object
extensive property
property that depends on the amount of matter in a sample
intensive property
property that depends on the type of matter in a sample not amount of matter
substance
matter with uniform and definite composition
physical property
quality or condition of a substance that can be observed or measured without changing the substance’s composition
solid
definite shape definite volume not easily compresed
liquid
indefinite shape definite volume not easily compressed
Gas
indefinite shape indefinite volume easily compressed
physical change
some properties of material change, but the composition of the material does not change
mixture
physical blend of two or more components
heterogeneous mixture
mixture where composition is not uniform throughout
homogeneous mixture
compostition is uniform throughout
solution
homogeneous mixture
phase
any part of a sample with uniform composition and properties
filtration
process separating solid from a liquid in a heterogeneous mixture
distillation
liquid boiled to produce vapor then condenced to for a liquid
element
simplist form of matter that has a unique set of properties
compound
substance that contains two or more elements chemically combined in a fixed porportion
chemical change
change that produces matter of a dif composition than the one before
chemical symbol
one or two lettered symbol
chemical property
ability of a substance to undergo a specific chemical change
product
substance produced in the reaction
reactant
substance present at the start of the reaction
chemical reaction
one of more substances change into one or more new substances
precipitate
sold that forms and settles out of a liquid mixture
law of conservation of mass
states that in any physical change or chemical reaction, mass is conserved. Mass is neither created nor distroyed
measurement
quantity that has both a # and a unit
scientific notation
given # is written as the product of two numbers
ex) 6.02 X 10^23
accuracy
measure of how close a measurement comes to the actual or true value of whatever is measured
precision
measure of how close a series of measurements are to one another
accepted value
correct value based on reliable references
experimental value
value measured in the lab
error
difference between experimental value and accepted value
percent error
absolute value of the error divided by the accepted value, multiplies by 100%
ex) percent error= |error|/accepted value X 100%
significant figure
include all digits that are known, plus last digit that is estimated
SI
revised version of the metric system
weight
force that measures the pull on a given mass by gravity
temperature
measure of how hot or cold an object is
the celsius scale
sets the freezing point of water to zero and boiling point to 100
kelvin scale
freezing point 273.15 K boililng 373.15 K
absolute zero
zero point on the Kelvin scale -273.15 degrees celsius
energy
capacity to do work or to produce heat
Joule (J)
SI unit of energy
1 J=0.2390 cal
1cal= 4.184 J
Calorie(cal)
quantity of heat that raises the temp of 1 g of pure water by 1 degree celsius
conversion factor
ratio of equivalent measurements
dimensional analysis
way to analyze and solve problems using units, or dimensions, of the measurements
Density
ratio of mass of an object to its volume
ex) D=M/V
atom
smallest particle of an element that retains its identity in a chemical reaction
electrons
negatively charged subatomic particles
cathode ray
glowing beam
protons
positively charged subatomic particles
neutrons
subatomic particles with no charge but with a mass nearly equal to that of a proton
nucleus
tiny central core of an atom and is composed of protons and neutrons
atomic #
# of protons in the nucleus
mass #
total # of protons and neutrons in atom
Number of neutrons
= mass #- atomic #
isotopes
atoms that have the same# of protons but different # of neutrons
atomic mass unit (amu)
defined as 1/12th of the mass of a carbon-12 atom.
atomic mass
weighted average mass of the atoms in a naturally occurring sample of the element.
period
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energy levels
fixed energies electron can have
quantum
amount of energy required to move an electron from one energy lever to another
atomic orbital
often thought of as a region of space in which there is a high probability of finding an electron
electron configuration
electrons arranged in various orbitals around the nuclei of atoms
aufbau principle
electrons occupy the orbitals of lowest energy first
pauli exclusion principle
atomic orbital may describe at most two electrons
hund’s rule
electrons occupy orbitals of the same energy in a way that makes the # of electrons with the same spin direction as large as possible
amplitude
wave’s height from zero to the crest
wavelenth
distance between the crests
frequency
v;# of wave cycles to pass a given point per unit of time
electromagnetic radiation
includes radio waves, microwaves, light etc
spectrum
different frequencies
atomic emission spectrum
frequencies of light emitted by electron
ground state
electron has lowest possible energy
photons
light quanta
heisenberg uncertainty principle
it is impossible to know exactly both the velocity and the position of a particle at the same time
periodic law
when elements are arranged in order of increasing atomic #, there is a periodic repetition of their physical and chemical properties
metals
good conductors of heat and electric currents
metalloid
generally has properties that are similar to those of metals and nonmetals
noble gases
elements in group 8A
representative elements
display a wide range of physical and chemical properties
inner transition metal
highest occupied s sublevel and a nearby f sublevel generally contain electrons
transition metals
highest occupied s and d sublevel contain electrons
anion
ion with negative charge
valence electrons
are the electrons in the highest occupied energy level
electron dot structures
diagrams that show valence electron dots
octet rule
in forming compounds atoms tend to achieve the electron configuration of a noble gas
halide ions
ions produced when atoms of chlorine and other halogens gain electrons
ionic compounds
compounds composed of cations and anions
ionic bond
electrostatic forces that hold ions together in ionice compounds
chemical formula
shows the kinds and #’s of atoms in the smalles representative unit of a substance
formula unit
lowest whole number ration of ions in an ionic compound
coordination #
# of ions of opposite charge that surround the ion in a crystal
Metallic bonds
consist of the attraction of free-floating valence electrons for the positively charged metal ions
alloys
mixtures composed of two or more elements at least one of which is a metal
covalent bond
atoms held together by sharing electrons
molecule
neutral group of atoms joined together by covalent bonds
diatomic molecule
molecule consisting of 2 oxygen atoms
molecular compound
compound composed of molecules
molecular formula
chemical formula of a molecular compound
single covalent bond
2 atoms held together by sharing a pair of electrons
structural formula
represents the covalent bonds by dashes and shows the arrangements of covalently bonded atoms
unshared pair
pair of valence electrons that is not shared between atoms
double covalent bond
bond involving two shared pairs of electrons
triple covalent bond
bond formed by sharing 3 pairs of electrons
coordinate covalent bond
covalent bond in which one atom contributes both bonding electrons
bond dissociation energy
energy required to break the bond between two covalently bonded atoms
resonance structure
structure that occurs when it is possible to draw two or more valid electron dot structures that have the same # of electron pairs for a molecular molecule or ion
molecular orbital
orbitals that apply to the entire molecule
molecular orbital
orbitals that apply to the entire molecule
bonding orbital
molecular orbital that can be occupied by two electrons of a covalent bond
sigma bond
when 2 atomic orbitals combine to for a molecullar orbital that is symmetrical around the axis connecting two atomic nuclei
pi bond
bonding electrons are most likely to be found in a sausage shaped regions above and below the bond axis of the bonded atom
tetrahedral angle
109.5
hybridization
several atomic orbitals mix to for the same total # of equivalent hybrid orbitals
nonpolar covalent bond
bonding electrons share equally
polar covalent bond
covalent bond between atoms in which the electrons are shared unequally
polar molecule
one end of the molecule is slightly negative and the other end is slightly positive
dipole interactions
occur when polar molecules are attracted to one another
dispersion forces
the weakest of all molecular interactions, are caused by the motion of electrons
hydrogen bonds
are attractive forces in which a hydrogen covalently bonded to a very electronegative atom is also weakly bonded to an unshared electron pair of another electronegative atom
network solids
solids in which all the atoms are covalently bonded to each other
binary compound
composed of 2 elements and can be either ionic or molecular
mole
representative particles measuring the amount of a substance
representative particle
refers to the species present in a substance
avagadros #
6.02 X10^23
molar mass
mass of mole
STP
temp of 0
percent composition
percent by which mass of each element in the compound
empirical formula
gives the lowest whole-number ratio of atoms of the elements in a compound
chemical equation
representation of a chemical reaction
skeleton equation
chemical equation that does not indicate the relative amounts of the reactants and products
catlyst
substance that speeds up
coefficients
small whole numbers placed in front of
balanced equation
each side of the equation has the same # of atoms
combo reaction
chemical change in which two or more substances react to form a single new substance
single replacement reaction
chemical change in which one element replaces a second element in a compound
activity series
lists metals of decreasing reactivity
combustion reactions
reacts with oxygen
complete ionic equation
equation that shows dissolved ionic compounds as dissociated free ions
spectator ion
ion appears on both sides
net ionic equation
directly involved