Chem 105 Test 1 (Ch. E-2) Flashcards
qualitative observations
descriptive in nature (e.g., changes in color/physical shape)
quantitative observations
measurements, counted values
measurements are a numerical value with a ? and ? unit
scalar and dimensional
systematic or determinate error
error is in the same direction (either higher or lower than should be)
random/indeterminate error
equal probability of measurement being lower or higher than it should be; difficult to correct/find source
SI unit for length, mass, time, temp, amount of a substance, electric current, and luminous intensity
meter (m), kilogram (kg), second (s), Kelvin (K), mole (mol), ampere (A), candela (cd)
mega- (M)
base x 10^4
kilo- (k)
base x 10^3
deci- (d)
base x 10^-1
centi- (c)
base x 10^-2
milli- (m)
base x 10^-3
micro- (mc or µ)
base x 10^-6
nano- (n)
base x 10^-9
pico- (p)
base x 10^-12
water boils at
212 F, 100 C, 373 K
water freezes at
32 F, 0 C, 273 K
absolute zero
-459 F, -273 C, 0 K
how to convert degrees Celsius to degrees Fahrenheit
F = 1.8(C) + 32
how to convert degrees Celsius to Kelvin
T(K) = t(*C) + 273.15
precision
repeat-ability
accuracy
actual closeness to value
significant figures rules
leading zeroes are not significant, trailing zeroes after a nonzero digit are not significant unless there is a decimal point
multiplication and division with significant figures
the least precise value determines the number of significant figures
addition and subtraction with significant figures
the value with the smallest decimal measurement determines the number of significant figures
density
mass / volume; an intensive physical property
physical or chemical changes in matter result in matter either gaining or releasing energy, which is ?
the capacity to do work
work
the action of a force applied across a distance
force
a pull or push on an object
electrostatic force
the push or pull on objects that have an electrical charge
first law of thermodynamics
energy of the universe is conserved
system
the area or location under study
universe
the system and its surroundings
endothermic reaction
heat transfers from surroundings to the system; the energy of the system increases, the energy and temperature of the surroundings decreases
exothermic reaction
heat transfers from the system to the surroundings; the energy of the system decreases, the energy and temperature of the surroundings increase
Calorie (cal)
the amount of heat needed to raise the temperature of 1g H2O by 1*C (1 cal = 4.184 J)
Kilocalorie (kcal)
1 kcal = 1000 cal = 4184 J
Joule (J)
the amount of heat that will change the temperature of 1g H2O by 1*C (4.184 J = 1 cal)
Kilojoule (kJ)
1 kJ = 1000 J
Diet Calorie (Cal or C)
1 diet calorie = 1 kcal = 1000 calories
kilowatt-hour (kWh)
1 kWh = 3.60 x 10^6 J
matter
anything that has mass and occupies space
atoms
basic submicroscopic particles that constitute the fundamental building blocks of ordinary matter
molecules
substances formed when two or more atoms come together (bond) in specific geometric arrangements
matter can be classified according to ? and ? (and define)
its state (its physical form - S, L, G - based on what properties it exhibits) and its composition (the types of particles - elements, compounds, mixtures)
matter can be broken down into two categories based on whether it is one type of particle or not
yes > pure substance
no > mixture
pure substances can be broken down into two categories based on whether it is separable into simpler substances
no > element
yes > compound
mixtures can be broken down into two categories based upon whether they are uniform throughout
no > heterogeneous (e.g. wet sand)
yes > homogeneous (e.g. tea with sugar)
element
a substance that cannot be chemically broken down into simpler substances; basic building block of matter; composed of a single type of atom
compound
a substance composed of 2+ elements in fixed, definite proportions
scientific method steps
observations, formulation of hypothesis, experimentation, formulation of laws and theories
law
what, empirical; a brief statement that summarizes past observations and predicts future ones
theory
why; a well-established hypothesis or set of hypotheses form the basis for a scientific theory; can be validated by experimental results, but can never be conclusively proven
observation
describes characteristics/behavior of nature
hypothesis
a tentative interpretation or explanation of the observations
a good hypothesis is ?
falsifiable (able to be proven wrong)
? and ? were the first to propose that matter was composed of small, indestructible particles
Leucippus and Democritus
Dalton’s atomic theory
- each element is composed of tiny, indestructible particles called atoms
- all atoms of a given element have the same mass and other properties that distinguish them from the atoms of other elements
- atoms combine in simple, whole-number ratios to form compounds
- atoms of one element cannot change into atoms of another element; in a chemical reaction, atoms change only the way that they are bound together with other atoms
the law of conservation of mass
in a chemical reaction, matter is neither created nor destroyed
Proust’s law of definite proportions
all samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constituent elements
Dalton’s law of multiple proportions
when two elements (call them A and B) form two different compounds, the masses of element B that combine with one gram of element A can be expressed as a ratio of small whole numers
JJ Thompson’s cathode ray experiments
discovered the electron
Millikan’s oil drop experiement
determined the charge of an electron (-1.60x10^-19 C/e-)
JJ Thompson’s plum pudding model
negatively charged electrons were small particles held within a positively charged sphere
Rutherford’s gold foil experiment results and conclusion
a majority of the particles did not pass directly through the foil, but some were deflected while some even bounced back; matter must not be as uniform as it appears - it must contain large regions of empty space dotted with small regions of very dense matter
nuclear theory of the atom
- most of the atom’s mass and all of its charge are contained in a small core called a nucleus
- most of the volume of the atom is empty space, throughout which tiny, negatively charged electrons are dispersed
- there are as many negatively charged electrons outside the nucleus as there are positively charged particles (protons) within the nucleus, so that the atom is electrically neutral
later work by Rutherford and his student James Chadwick demonstrated that ?
the previously unaccounted for mass was due to neutrons - the neutral particles within the nucleus
the mass of the ? and ? are most similar
proton and neutron
the charge of the ? and ? are equal in magnitude but opposite in sign
proton and electron
charge of an electron
-1.60218x10^-19 C
mass of an electron
0.00091x10^-27 kg
the number of ? defines the element; it is its atomic number (Z)
protons
isotopes
all atoms of a given element have the same number of protons, but not necessarily the same number of neutrons
mass number (A) represents
the sum of the number of neutrons and protons in an atom
format for representing isotopes (2 options)
1) the chemical symbol with the mass number to the top left and the atomic number to the bottom left of it
2) chemical symbol/name - mass number (X-A)
natural abundance of isotopes
the percentage value of the relative amount of each different isotope in a naturally occurring sample of a given element
ions
the number of electrons in a neutral atom is equal to the number of protons in its nucleus, but, in chemical changes, atoms can lose or gain electrons and become charged particles called ions
positively charged ions
cations (formed from metal elements)
negatively charged ions
anions (formed from nonmetal elements)
atomic mass
the average mass of the isotopes that compose that element, weighted based on the element’s natural abundance of each isotope
how to calculate atomic mass
the sum of the (fraction of isotope n) x (mass of isotope n)
mass spectometry
measures the masses of atoms and the % abundance of isotopes of an element by separating particles according to their mass
Avogadro’s number (1 mole = ?)
6.022x10^23
subatomic particles of matter
electrons, protons, neutrons
natural duality of subatomic particles
appear to exist in two conditions; wave-matter duality concept
the quantum mechanical model tells us (3 things) about an atom’s electrons
- it explains the manner in which electrons exist and behave in an atom
- it forms the foundation of chemistry by explaining the periodic table and its trends, the behavior of elements in chemical bonding, and the colors of the atoms/their size
- it predicts the atomic properties that are directly related to the behavior of the electrons
light
a form of electromagnetic radiation; composed of perpendicular oscillating waves (one for the electric field and one for the magnetic field)
speed of light
3.00 x 10^8 m/s
frequency (v or nu)
the number of waves that pass a point in a given period of time; units are Hertz (Hz) or cycles/s (s^-1) (1 Hz = 1 s^-1)
total energy (E)
proportional to the amplitude of the waves and their frequency
frequency equation
v = c / λ
visible light
400 to 700 nm (red to violet)
? light has the lowest frequency
radio-wave
? light has the highest frequency
gamma-ray
constructive interference
waves that interact so that they add to make a larger wave are said to be in phase
destructive interference
waves that interact so that they cancel each other are said to be out of phase
diffraction
when traveling waves encounter an obstacle or opening in a barrier that is about the same size as the wavelength, they bend around it
interference pattern
a characteristic of all light waves; the diffracted of light through two slits separated by a distance comparable to the wavelength results in an interference pattern of the diffracted waves
photoelectric effect
when light is shined on a metal surface, electrons are produced from the surface
experimental observations of the photoelectric effect
a minimum frequency was needed before electrons would be emitted regardless of the intensity, called the threshold frequency; high-frequency light from a dim source caused electron emission without any lag time
Energy equation
E = hv = h (c / λ)
Planck’s Constant (h)
6.626x10^-34 J*s
kinetic energy of the ejected electron
Ephoton - Ebinding (hv - Φ)
emission spectrum
when the light emitted when atoms or molecules absorb energy passes through a prism, a pattern of particular wavelengths of light is seen that is unique to that type of atom or molecule
? can be used to identify the elements present in a material as each element has its own unique spectrum
line spectra
Bohr developed a model of the atom to explain
how the structure of an atom changes when it undergoes energy transitions
Bohr model of the atom
electrons travel in orbits that are at a fixed distance from the nucleus; electrons emit radiation when they “jump” from an orbit with higher energy down to an orbit with lower energy
De Broglie proposed that particles could have wave-like character and predicted that the wavelength of a particle was inversely proportional to its momentum; relation:
λ = h / (mass * velocity)
1 J = 1 ?
kg * m^2 / s^2
electrons behavior characteristics
from particulate perspective (e.g. matter, mass) particle nature = position
from energy perspective (e.g. wavelength, frequency) wave nature = interference pattern
the wave and particle nature of the electron are ? properties, meaning ?
complementary - the more you know about one, the less you know about the other
Heisenberg’s Uncertainty Principle
Heisenberg states that the product of the uncertainties in both the position and speed of a particle was inversely proportional to its mass (Δx * mΔv > h/4pi)
determinacy
definite, predictable future
indeterminacy
indefinite future, can only predict probability
why can’t we predict an electron’s path?
according to classical physics, particles move in a path determined by the particle’s velocity, position, and forces acting on it, but we cannot know both the position and velocity of an electron - the best we can do is to describe the probability an electron will be found in a particular region using statistical functions
Schrodinger’s Equation
Hψ = Eψ; allows us to calculate the probability of finding an electron with a particular amount of energy at a particular location in the atom; solutions may produce wave functions, ψ
a plot of distance versus ψ^2 represents ?
an orbital, a probability distribution map of a region where the electron is likely to be found
4 quantum numbers
principal quantum number (n - energy), angular momentum quantum number (l - orbital type), magnetic quantum number (m sub l - position of orbital in an x-y-z plot), and the spin quantum number (m sub s - orientation of the spin of the electron)
principal quantum number, n, the energy level - values
n ≥ 1
angular momentum quantum number, l, orbital type - values
0 to n-1
magnetic quantum number, m sub l, position - values
-l to +l, including zero
Energy of n =
-2.18x10^-18 J (1 / n^2)
spin quantum number, m sub s - values
-1/2 for spin down or +1/2 for spin up
the number of sublevels within a level
n
the number of orbitals within a sublevel
2l+1
the number of orbitals in a level
n^2
ΔEelectron
Efinal state = Einitial state
ΔE = -2.18x10^-18 J [(1 / (nf)^2) - (1 / (ni)^2)]
ψ^2 the probability density
the probability of finding an electron at a particular point in space - decreases as you move away from the nucleus
probability distribution function
represents the total probability at a certain distance from the nucleus
the maximum value of the probability distribution function
is the most probable radius
nodes in the probability distribution function
are where the probability drops to zero
l=0
s orbital; each principle energy level has one s orbital; spherical shaped; number of nodes = (n-1)
l=1
p orbitals; each principle energy state above n=1 has 3 p orbitals; two-lobed; one node at the nucleus - total of n nodes
l=2
d orbitals; each principle energy state above n=2 has 5 d orbitals; mainly four-lobed “shaped” orbitals; planar nodes - higher principle levels also have spherical nodes
l=3
f orbitals; each principle state above n=3 has 7 f orbitals; mainly 8-lobed; planar nodes - higher principle levels also have spherical nodes
the phase of an orbital
orbitals are determined from mathematical wave functions, which can have positive or negative values as wells as nodes where the wave function = 0; the sign of the wave function is called its phase
