Exam 1 Flashcards
Polyatomic Ion
an ion composed of more than one atom
What are the polyatomic ions?
OH- Hydroxide
NO3- Nitrate
SO4-2 Sulfate
Examples of Chemistry in everyday life
digesting food
synthesizing polymers for clothing, cookware, and credit cards
refining cruel oil into gasoline and other products
The 3 domains of chemistry
Macroscopic
microscopic
symbolic
Macroscopic
realm of everyday things that are large enough to be sensed directly by human sight or touch
Microscopic
almost always visited in the imagination. some aspects are only visible through a microscope
Symbolic
the specialized language used to represent components of the macroscopic and microscopic domains
Matter
anything that occupies space and has mass
Solid
is rigid and possesses a definite shape
liquid
flows and takes the shape of its container
Gas
takes both the shape and volume of its container
Plasma
a gaseous state of matter that contains an appreciable amount of electrically charged particles
Mass
a measure of the amount of matter in an object
Weight
refers to the force that gravity exerts on an object
Law of Conservation of Matter
There is no detectable change in the total quantity of matter present when matter converts from one type to another
True for both chemical and physical changes
Element
a type of pure substance that cannot be broken down into simpler substances by chemical changes
Compounds
pure substances that can be broken into simpler substances by chemical changes
The two types of mixtures
Homogenous
heterogeneous
Homogenous mixture
exhibits a uniform composition and appears visually the same throughout
Solution
another name for homogenous mixture
Heterogenous mixture
has a composition that varies from point to point
Atom
the smallest particle of an element that has the properties of that element and can enter into a chemical combination
Molecules
consists of two or more atoms connected by strong forces known as chemical bonds
Properties
the characteristics that enable us to distinguish one substance from another
Physical property
a characteristic of matter that is not associated with a change in its chemical composition
Examples of Physical properties
density
color
hardness
melting and boiling points
electrical conductivity
Physical change
a change in the state or properties of matter without any accompanying change in its chemical composition
Chemical property
the change of one type of matter into another type (or the inability to change)
Examples of a chemical property
flammability
toxicity
acidity
reactivity
and heat of combustion
Extensive property
depends on the amount of matter present
Examples of an extensive property
mass, volume, heat
Intensive property
Does not depend on the amount of matter present
Examples of an intensive property
density
temperature
boiling point
Measurements provide three kinds of information
number- the size or magnitude of the measurement
unit- a standard of comparison for the measurement
indication of the uncertainty of the measurement
Femto f
10 to the -15
pico p
10 to the -12
nano n
10 to the -9
micro m
10 to the -6
mili m
10 to the -3
centi c
10 to the -2
deci d
10 to the -1
kilo k
10 to the 3
mega M
10 to the 6
giga G
10 to the 9
tera T
10 to the 12
SI unit of length
meter (m)
SI unit of mass
kilogram (kg)
SI unit of temperature
kelvin (K)
SI unit of time
second (s)
Volume
the measure of the amount of space occupied by an object
SI unit of volume
cubic meter (m3)
density
the ration of the mass of a sample of the substance to its volume
Density formula
mass divided by volume
SI unit for density
kilogram per cubic meter (kg/m3)
Exact number
result of a counting measurement, the only type of measurement that is free from uncertainty
significant figures
all the digits in a measurement, including the uncertain last digit
Are nonzero digits significant figures
yes always
are captive zeroes significant figures
Yes always
Are trailing zeroes significant figures
only when they are to the right of the decimal place or in scientific notation
Are leading zeroes significant figures
no
What is the significant figures rule when adding or subtracting numbers
round to the same number of decimal places as the number with the least number of decimal places
What is the significant figures rule when multiplying or dividing
round to the same number of digits as the number with the least number of significant figures
Less than 5
round down
more than 5
round up
deciding digit is 5
go up or down but make sure it ends up even
A measurement is precise if
it yields very similar results when repeated in the same manner
A measurement is accurate if
it yields a result that is very close to the true or accepted value
Dimensional analysis
the mathematical approach based on the premise that the units of quantities must be subjected to the same mathematical operations as their associated numbers
Conversion factor
a ratio of two equivalent quantities expressed with different measurement units
Celsius scale
water freezes at
0
Celsius scale
water boils at
100
Fahrenheit scale
water freezes at
32
Fahrenheit scale
water boils at
212
Kelvin scale
water freezes at
273.15
Kelvin scale
water boils at
373.15
Dalton’s Atomic Theory
- Matter is composed of exceedingly small particles called atoms. An atom is the smallest unit of an element that can participate in a chemical change
- An element consists of only one type of atom, which has a mass that is characteristic of the element and is the same for all atoms of that element
- Atoms of one element differ in properties from atoms of all other elements
- A compound consists of atoms of two or more elements combined in a small, whole-number ratio. In a given compound, the number of atoms of each of its elements are always present in the same ratio
- Atoms are neither created nor destroyed during a chemical change, but instead rearrange to yield a different type of matter
Law of Conservation of Matter
Atoms are neither created nor destroyed during a chemical change, then the total mass present when matter changes from one type to another will remain constant
Law of definite proportions
all samples of a pure compound contain the same elements in the same proportion by mass
Who discovered the electron
J.J. Thompson
How did J.J. Thompson discover the electron
Cathode ray tube
when a high voltage was applied across electrodes, a visible beam called a cathode ray appeared between them. Always deflected towards the positive charge and away from the negative charge
Much lighter than atoms
Electron
a negatively charged, subatomic particle with a mass more than one thousand times less than that of an atom
Robert A Millikan did what experiment
Oil drop experiment
What did the oil drop experiment find
The charge of the oil drops were always a multiple of a specific charge, so Millikan concluded that 1.6 x 10 to the -19 C was the charge of a single electron
Mass of an electron=9.107 x 10 to the -31 kg
Thompson thought atoms resembles _______ While Nagaoka proposed that atoms resembled ________
Plum pudding
Saturn
Who discovered the nucleus
Ernest Rutherford
What experiment did Ernest Rutherford perform
Gold foil scattering experiment
What did the Gold foil scattering experiment find
The volume occupied by an atom must consist of a large amount of empty space.
A small, relatively heavy, positively charged body, the nucleus must be at the center of each atom
nucleus contained most of the atom’s mass
Negatively charged electrons surround the nucleus
the proton is located in the nucleus
Proton
a positively charged, subatomic particle located in the nucleus
Isotopes
Atoms of the same element that differ in mass
Neutrons
uncharged, subatomic particles with a mass approximately the same as that of protons
also found in the nucleus
How are electrons and protons similar
charged subatomic particles
How are electrons and protons different
Different masses
Electron- negatively charged, in the rings around the nucleus
Proton- positively charged, in the nucleus
How are protons and neutrons simialar
same mass
both in the nucleus
How are protons and neutrons different
Protons are positive
Neutrons have no charge
What contains the majority of an atom’s mass
the nucleus
What occupy almost all of an atom’s volume
Electrons
amu
Atomic mass unit
e
fundamental unit of charge
Properties of a proton
Mass- 1.0073 amu
charge- +1
Properties of a neutron
Mass- 1.0087 amu
Charge- 0
Properties of an electron
Mass-0.00055 amu
Charge- -1
Atomic Number
the number of protons in the nucleus of an atom
the key to identifying atoms
Neutral atoms
the number of protons equals the number of electrons
Mass number
the total number of protons and neutrons in an atom
How to find the number of neutrons
the difference between the mass number and the atomic number
Ions
when the number of protons and electrons are not equal, the atom is electrically charged
equation for charge of an atom
number of protons-number of electrons
Atoms acquire charge by
losing or gaining electrons
Anion
an atom that gains one or more electrons and exhibits a negative charge
cation
an atom that loses one or more electrons and exhibits a positive charge
Chemical symbol
an abbreviation that we use to indicate an element or an atom of an element
Isotopes have
the same number of protons but the number of neutrons are different
Each proton and neutron has a mass of
about 1 amu
Electrons weigh less/more than a proton or neutron
far less
Atomic mass of a single atom in amu is approximately equal to its
mass number
Average mass
(fractional abundance x isotopic mass)
Example: Boron
19.9% 10B with a mass of 10.0129 amu
80.1% 11B with a mass of 11.0093
=(0.199 x 10.0129 amu)+(0.801x11.0093 amu)
= 10.81 amu -> what is on the periodic table
Mass spectrometry
how to find the occurrence and natural absences of isotopes
Molecular formula
a representation of a molecule or compound which consists of the following
- chemical symbols to indicate the types of atoms
- subscripts after the symbol to indicate the number of each type of atom in the molecule
Structural formula
shows the same information as a molecular formula but also shows how the atoms are connected
Empirical formula
indicates the simplest whole-number ratio of the number of atoms (or ions) in the compound
molecular formula
indicates the actual numbers of atoms of each elements in a molecule of a compound
Isomers
compounds with the same chemical formula but different molecular structures
Structural Isomers
Molecules that have the same formula but different structures and therefore different chemical properties
Mole
is an amount unit
defined as the amount of a substance containing the same number of discrete entities (such as atoms, molecules, or ions)
A mole provides
a link between the mass of a sample and the number of atoms, molecules, or ions in that sample
Avogadro’s Number
the number of entities composing a mole
6.02214179 x 10^23
molar mass
of an element is the mass in grams of 1 mole of that substance, a property expressed in units of grams per mole
molar mass of a substance is equivalent to
its atomic or formula mass in amu
- a single 12C atom has a mass of 12 amu
-a mole of 12C atoms have a mass of 12 g
Particles and waves are connected on a fundamental level called
wave-particle duality
Wave
an oscillation or periodic movement that can transport energy from one point in space to another
Speed of light
c= 2.998 x 10^8 m/s
Wavelength
distance between two consecutive peaks or troughs in a wave
Frequency
Number of successive wavelengths that pass a given point in a unit time
Amplitude
One-half the distance between the peaks and troughs
Waves are characterized by
Wavelength
frequency
amplitude
hertz (Hz)
the unit for frequency
common multiples of hertz
Megahertz (1 MHz= 1 x 10^6 Hz)
Gigahertz (1 GHz= 1 x 10^9 Hz)
The product of a wave’s wavelength and its frequency is
the speed of the wave
wavelength and frequency are
inversely proportional
as the wavelength increases, the frequency decreases and vice versa
Electromagnetic spectrum
the range of all types of electromagnetic radiation
Frequency=
speed of light divided by amplitude
Interference patterns
arise when light passes through narrow slits closely spaced about a wavelength apart
Dark regions correspond to regions where the peaks for the wave from one slit happen to coincide with the troughs for the wave from the other slit
destructive interference
brightest regions correspond to the regions where the peaks for the two waves happen to coincide
constructive interference
Standing waves
remain constrained within some region of space
play an important role in understanding of the electronic structure of atoms and molecules
one-dimensional standing wave
a vibrating string that is held fixed at its two end points is an example of this
quantization
only discrete values from a more general set of continuous values are observed
a system with fixed end points restricts the number and type of possible waveforms is an example of this
nodes
harmonic waves all have one or more points between the two end points that are not in motion
these points are called nodes
Continuous spectrum
sunlight consists of a range of broadly distributed wavelengths that form
Blackbody
a convenient, ideal emitter that approximates the behavior of many materials when heated
ultraviolet catastrophe
theoretical expressions as functions of temperature fit the observed experimental blackbody curves well at larger wavelengths.
but there are significant discrepancies at shorter wavelengths
Planck’s constant
quantity h
h=6.626 x 10^34 J s
used for the understanding of motions of atoms and subatomic particles, as well as how quantum mechanics and modern electronics operate
Photoelectric effect
the emission of electrons when electromagnetic radiation, such as light hits a material
does not depend on the brightness of the light but increased with increasing frequency of light
Photons
A particle representing a quantum of light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency but has zero rest mass
Wave particle duality
at deep fundamental level still not fully understood light is both wavelike and particle-like
Electrons are ejected when hit by
photons having sufficient energy (a frequency greater than the threshold
Photons produced in this manner have a range of energies, and thereby produce a
continuous spectrum
Continuous spectrum
an unbroken series of wavelengths
Line spectra
very narrow line widths interspersed throughout the spectral regions
each element displays its own characteristic set of lines
According to classical electromagnetic theory, only ________ should be observed
continuous spectra
Rydberg constant
1.097 x 10^7 m^-1
empirical formula that predicted all of hydrogen’s emission lines
1/amplitude= Rydberg constant (1/N1^2- 1/N2^2)
Bohr’s work convinced scientists to abandon classical physics and spurred the development of modern
quantum mechanics
Bohr incorporated what into classical mechanics description of the atom
Planck’s ideas of quantization
Einstein’s finding that light consists of photons whose energy is proportional to their frequency
assumed that the electron orbiting the nucleus would not normally emit any radiation
rather the electron emits or absorbs a photon if it moved to a different orbit
When the electron is in this lowest energy orbit (n=1), the atom is said to be in its
ground state
If the atom receives energy from an outside source, it is possible for the electron to move to an orbit with a higher n value
excited state
which has a higher energy
When the atom absorbs energy as a photon, th electron
moves from an orbit with a lower n to a higher n
when an electron falls from an orbit with a higher n to a lower n, the atom
emits energy as a photon
limitations of the Bohr model
unable to extend his theory to the next atom, He
does not account for electron-electron interactions in atoms with more than one electron
quantum numbers
integer numbers having only specific allowed values and used to characterize the arrangement of electrons in an atom
Wave-particle duality first observed with photons is actually a
fundamental behavior intrinsic to all quantum particles
Heisenberg Uncertainty Principle
it is fundamentally impossible to determine simultaneously and exactly both the momentum and the position of a particle
