Glossary of Midterm Chemistry Notecards

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what is matter
anything that has mass and takes up space
what is the mass of an object
the amount of matter the object contains
what is made up of matter
materials may differ in terms of the ____ of matter they contain
what is a substance
matter that has a uniform and definite composition
what are substances also referred to
pure substances
how many kinds of matter do substances contain
one kind of matter
why isn't lemonade a substance
not all samples of lemonade are identical
what is a physical property
a quality or condition of a substance that can be observed or measured without changing the substance's composition
what are examples of physical properties
color, solubility, odor, hardness, density, melting point, and boiling point
what are the three physical states
solid, liquid, and gas
what are examples of solids
coal, sugar, ice and iron
what is a solid
matter that has a definite shape and volume

shape of solid does not depend on the shape of its container

particles are packed tightly together

cannot be squashed into a smaller volume

expand only slightly when heated
what are examples of liquids
water, milk, and blood
what is a liquid
a form of matter that flows, has a fixed volume, and takes the shape of its container


expand when heated
what is always the same no matter what shape liquids take
the amount of space, or volume
particles in a gas are
spaced far apart
particles in a liquid are
particles are in close contact with one another, but are not rigidly packed
gases expand without
limit to fill any space
what is a gas
a form of matter that takes both the shape and volume of its container

easily compressed
difference between gas & vapor & steam
gas is limited to those substances that exist in the gaseous state at ordinary room temperature

vapor describes the gaseous state of a substance that is generally a liquid or solid at room temperature
what is steam
a gaseous form of water
why is steam referred to as a vapor
water is a liquid at room temperature and moist air contains water vapor
what is a physical change
such a change, which alters a given material withought changing its composition
what are examples of physical changes
cutting, grinding, bending, changes in room temp - melting & freezing of water, conversion of water to steam, condensation of steam to water
what is a mixture
a phsyical blend of two or more substances
what is one important characteristic of a mixture
their compositions may vary
what are the two kinds of mixtures
heterogeneous or homogeneous
what is a heterogeneous mixture
one that is not uniform in

composition of one portion of a mixture would be different from another portion
what is a homogeneous mixture
completely uniform composition

components are evenly distributed throughout the sample
what is the special name given to homogeneous mixtures by chemists
solutions may be
gases, liquids, or solids
what is a phase
any part of a system with uniform composition and properties
how many phases does a homogeneous mixture consist of
single phase
how many phases does a heterogeneous mixture consist of
two or more phases
how would you separate the components of tap water
what is distillation
when a liquid is boiled to produce a vapor that is then condensed again to be a liquid
describe the process of distilliation
first heated in a flask to form staem that enters a glass tube

the solid substances that originally dissolved in the water remain in the distillation flask bc they do not change into a vapor

the steam cools and forms droplets of water inside the tube

the water drips into a receiver, where its collected

the resulting distilled water is pure except for the dissolved gases

water from which even the dissolved gases are removed is a pure substance
what two groups can substances be classified into
elements and compounds
what are elements
the simplest forms of matter that can exist under labatory conditions
what cannot be separated into simpler substances by chemical means
what are the building blocks for all other substances
what are examples of elements
oxygen, hydrogen, and carbon
how can compounds be formed by elements
when two or more elements combine chemicall with one another
what are compounds
substances that can be separated into simpler substances only by chemical means
what is one process of separating compounds into simpler substances
how can you decide whether a sample of matter is a substance or a mixture
considering whether the material in question is always a single kind of material
what is a chemical symbol
a one or two letter symbol that represents elements
what do most of symbols for elements consist of
first one or two letters of the element's name
the first letter of a chemical symbol is always ______
if a second letter is used in a chemical symbol it is ______
in some cases, the symbol does not resemble the common name

these chemical symbols are derived from
latin or greek names
chemical symbols provide a shorthand way to
write the chemical formulas of compounds
the elements that make up a compound
are always present in the same proportion
a specific compound is always made up of the same
elements in the same proportions
the formula for a specific chemical compound
is always the same
what is a chemical reaction
when one or more substances change into new substances
what are the starting substances in chemical reactions
what are the substances formed in chemical reactions
what is a chemical property
the ability of a substance to undergo a chemical reaction and to form new substances
when is a chemical property observed
only when a substance undergoes a chemical change
what does a chemical change always result in
a change in chemical composition of the substances involved
what words signify a chemical change
burn, rot, rust, decomose, ferment, explode, and corrode
what does the arrow in a formula stand for
change into or produce
the reactants are written to the ____ side of the arrow
the products are written to the ___ side of the arrow
how can you tell whether a chemical reaction has taken place
energy is always absorbed or given off in chemical reactions

change in color

change in odor

production of a gas or solid from a liquid
what types of changes are reversible
physical changes
what types of changes not easily reversed
chemical changes
what is the most familiar chemical change
what is combustion
the quantity of matter is ______ during any chemical reaction
the mass of products is always ______ to the mass of reactants
what is the law of conservation of mass
in any physical change or chemical reaction, mass is neither created nor destroyed; it is conserved
what type of measurements will you use in chemistry
International System of Measurements (SI)
what are qualitative measurements
they give results in a descriptive, nonnumerical form
what are quantitative measurements
give results in a definite form, usually as numbers and units
what is scientific notation
when a number is written as the product of two numbers: a coefficient and 10 raised to a power
what is the exponent if the number is greater than ten in scientific notation
positive and equals the number of places the original decimal point has been moved tothe left to write the number in scientific notation
what is the exponent if the number is less than ten in scientific notation
negative exponent and value of exponent equals the number of places the original decimal point has been moved to the right to write the number in scientific notation
how do you multiply numbers written in scientific notation
multiply the coefficients and add the exponents
how do you divide numbers written in scientific notation
first divide the coefficients then

subtract the exponent in the denominator from the exponent in the numerator
what must you do before adding or subracting numbers written in scientific notation
you must make the exponents the same because the exponents determine the locations of the decimal points in the original numbers

the decimal points must be aligned before you add the two numbers
what is accuracy
a measure of how cloase a measurement comes to the actual or true value of whatever is measured
what is precision
a measure of how close a series of measurements are to one another
what does the precision of a measurement depend on
more than one measurement
how can one evaluate the accuracy of a measurement
it must be compared with the correct value
what is the accepted value
the correct value based on reliable sources
what is the experimental value
the value measured in the lab
what is the error
the difference between the accepted value and the experimental value
error can be positive or negative depending on
wheter the experimental value is greater than or less than the accepted value
what is the percent error
the absolute value of the error divided by the accepted value, multiplied by 100%
using the absolute value of the error means that
the percent error will always be a positive value
what are significant figures
all of the digits that are known, plus a last digit that is estimated
why must measurements always be reported to the correct number of sig figs
bc calculated answers depend upon the number of significant figures in the values used in the calculation
what is the International System of Units (SI)
a revised version of the metric system
what are the seven SI base units
mega, kilo, deci, centi, milli, micro, nano, pico
what is mega
1 mill times larger
1 000 000
what is kilo
1000 times larger
what is deci
10 times smaller
what is centi
100 times smaller
what is milli
1000 times smaller
what is micro
1 mill times smaller
1/1 000 000
what is nano
1000 mill times smaller
1/1 000 000 000
what is pico
1 trill times smaller
1/1 000 000 000 000
what is the order of the metric units of length
kilo, hecto, deka, g/l/m, deci, centi, milli
what is volume
the space occupied by any sample of matter
what is a liter
measures volume
how can you measure volume of a liquid
graduated cylinder, pipet, or buret, flask
when will the volume of any solid, liquid, or gas change
with temperature
the force of gravity on earth is about ___________ than on the moon
6 times
what is weight
a force that measures the pull on a given mass by gravity
what is mass
a measure of the quantity of matter
although the weight of an object can change with its location, it's mass
remains constant regardless of its location
objects can become _____ but never _____
weightless, massless
the mass of an object is measured in comparison to a standard mass of
1 kilogram
what can you use to measure the mass of an object
a platform balance
what is density
the ratio of the mass of an object to its volume
what is the units for density
grams per cubic centimeter
density is a characteristic property that depends on
only the composition of a substance not on the size of the sample
if the density of one sample is less than another, then what will happen
it will float on top of the other
because density is mass divided by volume, the desnity of a substance generally ____ as its temperature _______
decreases, increases
what is specific gravity
a comparison of the density of a substance with the density of a reference substance, usually at the same temperature
what are the units for specific gravity
no units
how can the specific gravity of a liquid be measured
what are examples of uses of specific gravity
diabetes, checkin condition of antifreeze in your car, acid in an automobile battery
what a three-step-problem-solving approach
1. analyze
2. calculate
3. evaluate
how do you find density
density = mass / volume
how do you find volume
volume = mass / density
how do you find mass
mass = density x volume
what is a conversion factor
a ratio of equivalent measurements

the measurement in the numerator is equivalent to the measurement in the denominator
another way to look at conversion factors
smaller number & larger unit
larger number & smaller unit
what is dimensional analysis
a way to analyze and solve problems using the units or dimensions of the measurements
what did democritus of abdera, a teacher who lived in Greece during th fourth century b.c., first suggest?
the existence of the tiny fundamental particles that make up matter
what did democritus call the tiny fundamental particles that make up matter
what did the beleive about atoms
that they were indivisible and indestructible
what did democritus's not work
they were not useful in explaining chemical behavior

lacked experimental support
the modern process of discovery regarding atoms began with
john dalton

english schoolteacher
what did dalton do that democritus didn't do
performed experiments to test and correct his atomic theory
what did dalton study
the ratios in which elements combine in chemical reactions
what did dalton form based onthe results of his experiments
hypotheses and theories to explain his observations
what is Dalton's atomic theory
1. all elements are composed of tiny indivisible particles called atoms

2. atoms of the same element are identical. the atoms of any one element are different from those of any other element

3. atoms of different elements can physically mix together or can chemically combine with one another in simple whole-number ratios to form compounds

4. chemical reactions occur when atoms are separated, joined, or rearanged. atoms ofone element, however, are never changed into atoms of another element as a result of a chemical reaction
what is an atom defined as
the smallest particle of anelement that retains the properties of that element
how many copper atoms could u line up to produce a 1cm line?
1 000 000 000
how can you see atoms
scanning tunneling microscope
what is one important change today about dalton's atomic theory
atoms are now known to be divisible

they can be broken down into evensmaller, more fundamental particles
what are the tree kinds of subatomic particles
electrons, protons, and neutrons
what are electrons
negatively charged subatomic particles
who discovered electrons
J.J. thomson
how did thomson discover electrons
he performed experiments that involved passing electric current through gases at low pressure
thomson sealed the gases in glass tubes fitted at botheds with metal disks called
what is an anode
a positively charged electrode
what is a cathode
negatively charged electrode
what is the cathode ray
a glowing beam that formed between the electrodes, from cathode to the anode
what are cathode rays attracted to
metal plates that have a positive lectrical charge
plates that carry a negative electrical charge ______ the rays
what did thomson propose about cathode rays
that its a stream of tiny negatively charged particles moving at high speed (electrons)
thomson also showed that the production of cathode rays did not depend on
the kind of agas in the cathode-ray tube or the type of metal used for the electrodes
what did thomson conclude
that electrons must be parts of the atoms of all elements
thomson and other determined that an electron's mass is about ________ of the mass of a hydrogen atom
the american scientist robert a milikan carried out experiments that allowed him
to find the quantity of charge carried by an electron

determined the ratio of the charge to the mass of an electron
an electron carries exactly
one unit of negative charge
the mass of an electron is ______ the mass of a hydrogen atom (millikan)
atoms have no net electric charge, so they are
electrically neutral
waht did E Goldstein observe
a cathode ray tube and found rays traveling in the direction opposite to those f the cathode rays
what did goldstein call the rays that he observed
canal rays
what did he conclude of canal rays
thy they were composed of positive particles
what are protons
positively charged subatomic particles
each proton has a mass about ______ times of that an electron
who confirmed the existence of the neutron
james chadwick
what are neutrons
subatomic particles with no charge
wat does the mass of a neutron nearly equal
the mass of a proton
the fundamental building blocks of atoms are
electrons, protons, and neutrons
what did ernest rutherford's test use
the relativey massive alpha particles
what are alpha particles
helium atoms that have lost their two electrons and have a double positve charge because of the two remaining protons
what did rutherford do in his experiment
directed a narrow beam of alpha particles at a very thin sheet of gold foil
what was the prevailing theory
the alpha particles should have passed easily through the gold with only a slight defelection due to the positive charge thought to be spread out in the gold atoms
the great majority of alpha particles
passed straight through the gold atoms without deflection
a small fraction of the alpha particles
bounced off the gold foil at very large angles

some even bounced straight back toward the source
what was the new theory that rutherford suggested about atoms
that they were mostly empty space (lack of deflection of most of the alpha particles)
what did rutherford conclude
all the positive charge and almost all the mass are concentrated in a small region that has enough positive charge to account for the great defelection of some of the alpha particles
what is the nucleus
central core of an atom and is composed of protons and eutrons
what is the atomic number of an element
the number of protons in the nucleus of an atom of that element
what does the atomic number identify
an element
the number of protons equal the
number of electrons
why do the number of electrons in an atom always equal the number of protons in the nucleus
because atoms are electrically neutral
what is the mass number
the total number of protons and neutrons in an atom
if you know the atomic number and mass number of anatom you can determine
the atom's composition
how can you find the number of neutrons
mass number - atomic number
how can you use the mass number and the name of the element to designate atoms

(example of gold)
what are isotopes
atoms that have the same number of protons but different numbers of neutrons
isotopes also have different _____ _______ because they have diff numbers of neutrons
mass numbers
why are isotopes chemically alike
they have identical numbers of protons and electrons
wat are the three known isotopes of hydrogen
most common hydrogen isotop
no neutrons
mass number of 1
one neutron
mass number of 2
two neutrons
mass number of 3
what is atomic mass unit (amu)
1/12 the mass of a carbon-12 atom
waht is the atomic mass of an element
a weighted average mass of the atoms in a naturally occuring sample of the element
what did Dmitri Meneleev do
listed the elements in columns in order of increasing atomic mass

arranged the columns so that the elements with the most similar properites were side by side
dmitri mendeleev constructed
the periodic table
what is the periodic table
an arrangement of the elements according to similaities in their properties
why did mendeleev leave blank spaces in the table
there were no known elements with the appropriate properties and masses
what did henry mosely do
determined the atomic number of the atoms of the elements

arranged the elements in a table by order of atomic number instead of atomic mass
how is the periodic table arranged today
in order of atomic number
where is the atomic number of each element shown
centered above the symbol
where is the atomic mass and the name of the element shown
below the symbol
the elements are listed in order of _______ atomic number
what are periods
horizontal rows of the periodic table
how many periods are there in the periodic table
what is the periodic law
when the elements are arranged in order of increasing atomic number there is a periodic repitition of their physical and chemical properties.
elements that have similar chemical an dphysical properties end up in the same
what is a group or family
each vertical column of elements in the periodic table
the elements in any group of the periodic table have similar
physical and chemical properties
what are Group A elements called and why
representative particles

they exhibit a wide range of both physical and chemical properties
what are metals
high electrical conductivey and a high luster when clean
except for hydrogen, the reprentative particles onthe left side of the table are
what are the Group 1A called
alkali metals
what are the Group 2A called
alkaline earth meatls
most of the elements that are not Group A elemnts are also metals which include
transition metals and inner transition metals
what are the Group A elements
Group A1-Group7A and Group 0
what do inner transtion and transition metals make up
the Group B elements
inner-transition metals
appear below the main body of the periodic table

also called rare-earth metals
all metals are solid at room temp except for
about 80% of all elements are
nonmetals occupy what part of the periodic table
upper-right corner
what are nonmetals
elements that are generally nonlusterous and that are generally poor conductors of electricity
the nonmetals of Group &A are caleld
wat are the nonmetals of group 0 known as
noble gases
what does the heavey stair-step line divide
metals from nonmetals
wat are most of the elements that border tisline
what are metalloids
elements with properties that are intermediate between those of metals and nonmetals
what are the building materials of the substances that make up all living and nonliving things
which elements tend to exist as isolated atoms
noble gas elements
what does monatomic mean
they consist of single atoms
what is a molecule
the smallest electrically neutra unit of a substance that still has the properties of the substance
what are molecules made up of
two or more atoms that act as a unit
what are molecular compounds
compounds composed of molecules
what do molecular compounds tend to have
relatively low melting and boiling points
what are the molecules in molecular compounds composed of
two or more nonmetals
the molecules of a given molecular compound
are all the same
what are ions
atoms or groups of atoms that have a positive or negative charge
when does an ion form
when an atom or group of atoms loses or gains electrons
what is a cation
any atom or group of atoms that has a positive charge
a cation has _____ electrons than the electrically neutral atom from which it formed
for metallic element, the name of a cation is the same as
the name of the element
what are anions
atoms or groups of atoms that have a negative charge

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