chapter 2: atoms, molecules,, and ions Flashcards
question of whether matter is or isn’t … led to many ….
continuous; experiments
antoine Lavoisier’s experiments resulted in the
law of conservation of mass
law of conservation of mass: mass is neither … nor .. during
gained; destroyed; chemical reactions
law of constant composition: all samples of pure substance have the
same elements in the same proportions by mass
law of multiple proportions: for compounds that are formed by the same elements, the masses of the first element that combine with a certain mass of the second element is always
a ratio of small whole numbers
Democritus proposes matter is … and called the smallest particles of matter…
discontinuous; atoms
(Dalton’s theory) all matter is made up of
atoms
(Dalton’s theory) atom: smallest unit of an element that
retains the properties of the element
(Dalton’s theory) element is made up of one type of …, and the properties of the atoms of an element are ..
atom; identical
(Dalton’s theory) compounds have atoms of
2 or more elements
(Dalton’s theory) the number of atoms in a compound is
the same
(Dalton’s theory) atoms merely…during chemical reactions
rearrange
(Dalton’s theory) explanation of law of constant composition: compounds are always composed of the same
atoms in the same ratios
(Dalton’s theory) explanation of the law of multiple proportions: compounds can be made from the same elements in different ratios in which the ratio of atoms will be
whole numbers
(Dalton’s theory) explanation of law of conservation of mass: in chemical reactions, atoms are merely …., …., and ….; since the number of atoms and the atoms themselves aren’t changing, the mass
rearranged; combined; separated; doesn’t change either
atoms can be … into several different ..
subdivided; subatomic particles
the three major subatomic particles comprising atoms include:
protons, neutrons, and electrons
the manner in which atoms combine and behave is determined by the … and .. of each subatomic particle
number; type
JJ Thomson used a gas discharge tube to show that cathode rays were
electrically charged particles
cathode rays traveled in …. and were deflected by … and …
straight lines; electric and magnetic fields
Thomson determined by the direction of the rays’ deflection that the particles were
negatively charged
electrons:
negatively charged particles
Robert A. Milikan measured the
charge of the electron
(Milikan’s experiment) exposed tiny oil drops to
high-energy radiation
(Milikan’s experiment) measured the rate that the electrically charged oil droplets fell in the
presence/absence of an electric field
(Milikan’s experiment) calculated the … on the oil drop
charge
(Milikan’s experiment) noted that the charge was a multiple of a
single quantity
(Milikan’s experiment) this quantity is the charge of an
electron (e)
with the knowledge of the charge, the … of the electron was measured
mass
in a study meant to analyze deflection of alpha particles as they passed through gold foil, Rutherford recognized that some of the alpha particles were
deflected back toward the source
Rutherford proposed a nuclear model of the atom, which suggested that atoms contain
nuclei of positive charge
nucleus contains most of an atom’s
mass
electrons comprise most of the atom’s
volume
Rutherford found that every element has a different
positive charge
Rutherford suggested the existence of a
proton
the mass of the proton is … times that of the electron
1836
Rutherford was unable to explain why protons were,….., considering that …. between like charges typically exists
close together; repulsion
the existence of a neutral particle was proposed because the proton didn’t account for
the entire nuclear mass
james chadwick discovers
neutrons
neutron’s mass is close to that of a
proton
strong nuclear binding forces hold the particles of nuclei
together
ratio of neutrons to protons is around:
1.0 to 1.6
charges of the electron and proton are equal in
magnitude.
atoms contain equal numbers of
electrons and protons
mass of protons and neutrons are almost equal, while the mass of an electron is
very small
atomic number (Z): amount of .. in an atomic nucleus; … an element
protons; identifies
number of neutrons in atoms of the same element are not always the same:
isotopes
mass number (A): amount of
protons and neutrons in an atom
isotopes have the same … but different ..
atomic number; mass numbers
most elements occur in nature as mixtures of
stable isotopes
about 75% of naturally occurring elements have
2 or more stable isotopes
isotopes disproves one aspect of
Dalton’s atomic theory
to portray specific isotopes, the following notation is used:
a X
z
X→
element’s symbol
a→
mass number
z→
atomic number
the atomic number and element’s symbol do not both have to be included, because either one can
identify the element
ions: charged atoms that are formed when atoms
lose/gain electrons
cation: … formed when an atom … one or more electrons
positive ion; loses
anion: ….; formed when an atom … one or more electrons
negative anion; gains
notation used to identify ions, and notation used to identify isotopes can be
combined
atomic mass unit (u):
1/12 mass of Carbon-12 atom
atomic mass unit is the standard unit to measure
atomic mass
all other atomic masses are compared with the
Carbon-12 standard
1 u =
1.66 x 10-27 kg
masses of neutrons and protons are approximately
1 u
atomic masses of all the elements found with
mass spectrometers
(mass spectrometer) a sample of an element in gaseous form is exposed to a beam of high energy electrons which convert the atoms of the element to
cations
(mass spectrometer) a magnetic field deflects the cations into a
curved path
(mass spectrometer) the degree of curvature determines the
mass and charge of the ion
(mass spectrometer) the charge to mass ratio of the ions is then
calculated
mass spectrometer measures .. and …. of isotopes in a sample of an element
masses; relative abundance
isotopic compositions of most naturally occurring elements are … and aren’t influenced by the … of the sample
constant; origin
isotopic mass: mass of an
isotope of a given element
a weighted average mass can be calculated that considers the
abundance of isotopes
atomic mass: weighted … of the naturally occurring element
average mass
atomic mass is an average: portrays natural isotopic
distribution of an element
classification of elements enables comprehension of
elements’ properties
periodic table arranges the elements into …, with elements of similar properties falling in the same …
rows; column
Mendeleev initially arranged elements by increasing …., although he deviated from this to place elements with similar … together
atomic mass; properties
Mendeleev predicted the existence of other
elements
Moseley ordered the elements based on their
atomic numbers
period: … of the periodic table
horizontal row
properties of elements vary across
periods
groups: …. of the periodic table
columns
properties of elements in the same groups are
similar
numbers associated with rows refer to the outermost … in which electrons can be found in their ground state
energy level
numbers associated with groups can provide insight into the …. in the outermost energy level of an atom
electron configuration
classification of elements also involves indicating whether the elements are
metals, nonmetals, or metalloids
metal:
shiny, good electrical conductor
nonmetals: elements that don’t …, elements in … part of the periodic table
conduct electricity; top right
metalloids: have properties of … and ….; …. of electricity; elements along the line that divides … and ….
metals nonmetals; semiconductors; metals; nonmetals
representative/ main-group elements: elements in groups
1,2, 13-18
transition metals: … block elements from group ..
d; 3-12
lanthanides: elements that follow
lanthanum
actinides: elements that follow
actinium
inner transition metals:
lanthanides and actinides
alkali metals (group 1):
soft, low melting metals, reactive, abundant
alkali metal reactivity increases
down the group
alkali metals occur in compounds rather than as
free elements
alkaline earth metals (group 2) less reactive than
alkali metals
Mg and Ca are
abundant
halogens (group 17): term means
salt formers
halogens (group 17): among most reactive
nonmetals
halogens (group 17): reactivity decreases down the
group
halogens (group 17): fluorine is the most … of all the elements
reactive
chlorine is the most … of the halogens
abundant
noble gases (group 18): generally
unreactive
molecule: combination of atoms that acts as a single particle due to the strong
attraction between the atoms
molecules are electrically
neutral
molecules of different atoms form
molecular compounds
diatomic molecules consist of
2 atoms
if all the atoms in a molecule are the same, the substance is
an element
if atoms of two or more elements are present, the substance is a
molecular compound
molecular formula: shows the … of a molecule and indicates the number of each
composition; type of atom in a molecule
subscripts give the number of
atoms of an element
structural formula: shows how atoms are c
connected in a molecule
molecular mass: sum of the masses of a molecule’s
atoms
molecular mass is expressed in
atomic mass units
the number of sig figs when calculating atomic mass is sometimes
random
(atomic mass) use either one or two digits after the decimal point, whichever corresponds with the
precision that is wanted
some compounds contain elements in the form of
ions
ionic compound: compound do
cations and anions that are joined together
ionic compounds are held together by
electrostatic forces
all ionic compounds are electrically neutral because the sum of the charges of the cations and anions equal
zero
the exact number of ions in an ionic crystal varies with the
size of the sample
empirical formula: gives the relative numbers of atoms in a substance with the smallest possible
whole-number subscripts
empirical formulas of ionic compounds indicate
electrical neutrality
empirical formulas of ionic compounds indicate
electrical neutrality
metals form
cations
nonmetals form
anions
for groups 1-3, the metals form cations that have charges that are equal to their
group numbers
main group nonmetals form anions that have charges based on their distance from the
noble gases
when charges of ions in an ionic compound are known, the formula is written by adjusting the … on the ions so that the sum of charges is …
ions; zero
monatomic ions: ions that are formed from
single atoms
polyatomic ion: group of atoms with a
charge
polyatomic ions behave like a …. because of the
single particle; strong attractive forces
ammonium is the most common
polyatomic cation
empirical formula of an ionic compound with polyatomic ions is also dependent on
charges
formula mass: sum of atomic masses of all atoms in an ionic compound’s
empirical formula
formulas for ionic compounds give the relative numbers of
cations and anions
for monatomic ions: cation is named by the element’s …; anion is the root of the element name with suffix …
name; -ide
binary compounds: comprised of
2 elements
name of binary compounds doesn’t include
numerical prefixes
name of polyatomic ions are used in the
compound name
metals from other groups can have more than one
cation
…. used to specify the charges of metals that have more than one cation
roman numerals
older system with suffixes … and … to indicate charges
-ous; -ic
acids: produce … in aqueous solution
hydrogen ions
when the name of the anion ends in -ide (exception: hydroxide), acid name is found by adding prefix … and changing the ending to ..; followed by the word ..
hydro-; -ic; acid
anions found in acids combine with a sufficient number of hydrogen ions to give
electrical neutrality
if polyatomic anion ends in -ate, the name of the acid will end in … followed by ..
-ic; acid
if polyatomic anion ends in -ite, the name of the acid will end in … followed by …
-ous; acid
(molecular compounds) element father to the left in the periodic table is given
first
(molecular compounds) element closer to the bottom in any group is given
first
(molecular compounds) We name the 1st element in the compound followed by the name of the 2nd element with its ending changed to
ide
prefixes indicate the number of atoms of each element in
a molecule
(molecular compounds) hydrogen is given second when it combines with elements from groups
1A to 5A
(molecular compounds) hydrogen is first when it combines with group
6A and 7A
oxygen is always last, except when it combines with
fluorine
general order in which elements are given in a molecular compounds formula:
B, Si, C, As, P, N, H, Se, S, I, Br, Cl, O, F
organic compounds: compounds that have
carbon
hydrocarbons: organic compounds that only have
hydrogen and carbon
alkanes: simplest class of
hydrocarbons
general formula for alkanes is:
CnH2n+2
alkanes have an … ending
-ane
(alkanes) linear chains of carbon with enough hydrogen sot that each carbon is connected to
4 other atoms
alkanes with more than three carbon atoms may have different arrangements of carbon chain that have
branching
for those that are branched, the substituent attached to the longest chain is the
alkyl group
names of alkanes are based on the length of the
hydrocarbon chain
n-alkanes are
straight, unbranched chains
(names of alkanes) methane
CH4
(names of alkanes) ethane
C2H6
(names of alkanes) propane
C3H8
(names of alkanes) n-Butane
C4H10
(names of alkanes) n-Pentane
C5H12
(names of alkanes) n-Hexane
C6H14
(names of alkanes) n-Heptane
C7H16
(names of alkanes) n-Octane
C8H18
(names of alkanes) n-Nonane
C9H20
(names of alkanes) n-Decane
C10H22
(names of alkanes) methyl
CH3 -
(names of alkanes) ethyl
C2H5 -
(names of alkanes) propyl
C3H7 -
(names of alkanes) butyl
C4H9 -
(names of alkanes) pentyl
C5H11 -
(names of alkanes) hexyl
C6H13 -
(names of alkanes) Heptyl
C7H15 -
(names of alkanes) Octyl
C8H17 -
(names of alkanes) Nonyl
C9H19-
(names of alkanes) decyl
C10H21 -
cycloalkanes: hydrocarbons that contain a
ring of carbon atoms
cycloalkanes formula
CnH2n
substituents of cylcoalkanes are named in the same manner as alkanes, except they have the prefix
cyclo-
When branching occurs in alkanes, branched hydrocarbon substituents are referred to as … and the ane ending is removed and a … ending is added
alkyl groups; -yl
(naming alkanes) locate the longest .. or biggest ..
chain; ring
(naming alkanes) locate substituents and number the chain to minimize the number of the
substituent
(naming alkanes) name the substituent, properly located on the chain by a number followed by a
dash
(naming alkanes) add the base alkane name of the longest
carbon chain
more complex organic compounds have
functional groups
functional groups: atoms/ small groups of atoms that undergo
reactions
halogesn are
functional groups
molecular compounds form when two or more
nonmetals combine
(ionic solids) 3d structure held by strong
electrostatic orces
(ionic solids) hard, brittle
crystalline solids
(ionic solids) high melting
points
(ionic solids) must be heated to very high temperatures to be
vaporized
(ionic solids) when ionic substances dissolve they separate into
cations and anions (dissociation)
(ionic solids) when ionic substances that have polyatomic ions dissolve, the polyatomic ions do not
separate
(ionic solids) measuring electrical conductivity distinguishes ionic compounds from most
molecular compounds
(ionic solids) solid ionic compounds don’t
conduct electricity
(ionic solids) electrolyte: substance that produces ions when
dissolved in water; conduts electricitiy
(ionic solids) pure water and solutions of most other molecular compounds are poor electrical conductors→
nonelectrolyte
(small molecular compounds) typically exist as .., …, or …
gases; liquids; low-melting solids
(small molecular compounds) forces that hold one molecule to another are
weak
(small molecular compounds) low melting
points
(small molecular compounds) in liquid phase: molecules are close but can
move
(small molecular compounds) in gas phase: molecules are moving and
far apart
(small molecular compounds) no phase conducts
electricity
