Physics Flashcards
atomic number
number of protons in an atom’s nucleus
atomic mass
sum of mass of protons and neutrons
mass number
sum of protons and neutrons
isotopes
atoms of the same element that have different number of neutrons
nuclear force
force between 2+ parts of the atomic nuclei that is responsible for the binding of protons and neutrons
radioactive decay
occurs when some isotopes are unstable and this reaction releases energy to achieve a more stable nuclear configuration
half-life
time taken for the activity of a given amount of a radioactive substance to decay to half of its initial value
mass spectrometer
separates compounds based on mass-to-charge ratio (mass of the atom/charge)l
orbital
physical space where the electron is likely to be present
n quantum number
energy shell/level of an atom
l quantum number
subshell
ground state
electrons in an atom want to be arranged in a way so that the energy of an atom is as low as possible
photon
source of energy that electrons can absorb the make jump to a higher energy level
atomic emission spectrum
pattern of lines formed when light passes through a prism to separate it into the different frequencies of light it contains
pauli exclusion principle
states that no 2 electrons in an atom can have the same set of 4 quantum numbers
diamagnetism
electrons are paired, total spin = 0, slightly repelled
paramagnetism
electrons is unpaired, orbital has a net spin, slightly attracted to a magnetic field
aufbau principle
illustrates the filling order for atomic orbitals
bohr model
states that electrons encircle the nucleus in orbitals, electrons are not allowed to occupy any of the spaces in between the orbits
bohr model is based on the
wave-particle duality principle
heisenberg uncertainity principle
states that it is impossible to determine both the position and velocity of an electron simultaneously
shielding effect
decrease in the attraction between an electron and the nucleus in any atom with more than 1 electron shell
Zeff (effective nuclear charge)
net positive charge experienced by an electron in an atom
-seen on PT
photoelectric effect
when light strikes materials, it can eject electrons form them
E (photon) = hf
when the absorbed energy is greater than the atom ionization energy, the electron will
leave the atom w/ KE
KE = hf - IE
alkali metals
highly reactive +1 ox state, reactive with H and water
alkaline earth metals
melt at high temps, +2 ox state, reactive, only exists in compounds
chalcogens/oxygen group
contains metalloids and nonmetals
halogens
F, Cl, Br, I
-highly reactive, -1 ox state
noble gases
nonreactive, gases at RM
transition metals
high electric conductivity due to d-orbital electrons, different ox states
representative elements
have valence electrons in orbitals of either s or p
metals
found on left and middle of PT
-have high melting points, high densities, shiny, malleable, ductile, low Zeff, low EN, large atomic radius, small ionic radius, low ionization energy
non-metals
found on upper right side of PT
- high ionization energy, high electron affinity, high EN
- small atomic radii, large atomic radii, poor conductors of heat and electricity since they don’t want to give up electrons
ionization energy
energy required to remove electrons from gaseous atoms or ions
as atomic radius decreases , it becomes harder to
remove an electron that is closer to the nucleus
ionization energy increases as…
one moves across a period b/c electrons are held together by a higher effective nuclear charge
-decreases as one moves down a group since valence electrons are farther away from nucleus and experience greater shielding
electron affinity
energy change that occurs when a neutral atom gains an electron
electronegativity
tendency of an atom/molecule to attract electrons
molecular weight
total mass of atoms in a molecule, represented by grams/mol
molecular formula
indicates the actual number of atoms in a compound
empirical formula
indicates the smallest whole-number ratio of atoms in a compound
percent composition
mw of element/mw of empirical formula * 100
density
an object’s “compactedness” or mass/volume
oxidation number
describes the degree to which an element can be oxidized or reduced
oxidizing agent
substance that causes oxidation by accepting electrons
reducing agent
substance that causes reduction by losing electrons
percent yield
actual/theoretical yield * 100
cations
fewer # e than p, smaller
anions
more e than p, larger
ml quantum number
location of an orbital within a subshell (-l to +l)
hund’s rule
electrons will not fill any orbital in the same subshell until all orbitals in that subshell contain 1 electrons
covalent bonds
formed when the nuclei of 2 atoms share a pair of electrons, found between nonmetals
nonpolar covalent bonds
have equivalent EN
polar covalent bonds
significant difference in EN (partial ionic character)
ionic bond
very different EN, occurs between metals and nonmetals (special electrostatic interactions)
E is _ when bonds are broken
released
dipole moemnt
center of positive charge is displaced form center of negative charge
-u = qd
intermolecular attraction
attractions between separate molecules proportional to the magnitudes of their dipoles
conductors
allow electrons to flow relatively freely
resistors
hold electrons tightly in place
current
moving charge, in the direction of the movement of positive charge
increase in T = _ in resistance
increase
voltage of a battery is determined by
the difference between the potentials of the cathode and anode
capacitor
store energy in a circuit
dielectric constant (k)
refers to the substance between the plates of an capacitor, acts to resist the creation of an electric field allowing the capacitor to store more charge
insulator
a material in which electric current does not flow freely.
ammeter
measures the current flowing through a circuit. to maximize current, the resistance within the ammeter is almost 0
voltmeter
measures the potential difference between any two points on a circuit, resistance within the voltmeter is functionally infinite
multimeter
serves as both an ammeter and voltmeter
conduction
“contact”, exchange of KE between microscopic particles (hi temp substance moves to low temp substance)
convection
energy transferred by movement of a fluid (gas/liquid)
radiation
conversion of thermal E to electromagnetic waves
expansion: Wsys, Ein
Wsys > 0, Ein < 0
compression: Wsys, Ein
Wsys < 0, Ein > 0
