General Chemistry Flashcards
Proton
positive charge
mass around 1 amu
Neutron
no charge
mass around 1 amu
Electron
negative charge
negligible mass
What subatomic particles are in the nucleus?
protons and neutrons, electrons move around the nucleus
Atomic number:
number of protons in an element
mass number:
sum of an elements protons and neutrons
atomic mass:
equal to mass number; sum of an elements protons and neutrons
Isotopes:
atoms of a given element with the same atomic number that have different mass numbers; differ in number of neutrons
3 isotopes of hydrogen:
protium, deuterium, and tritium
atomic weight:
weighted average of the naturally occurring isotopes of an element
Rutherford:
atom has a dense, positively charged nucleus that made up only a small fraction of the volume of an atom
Bohr model of the atom:
a dense, positively charged nucleus is surrounded by electrons revolving around the nucleus in orbits with distinct energy levels
quantum
described by Planck, energy difference between energy levels
Quantization:
there is not an infinite range of energy levels available to an electron; electrons can only exist at certain energy levels. The energy of an electron increase the farther it is from the nucleus
Atomic absorption spectrum:
for an electron to jump from a lower energy level to a higher one, it must absorb an amount of energy equal to the energy difference between the two levels
atomic emission spectrum:
when electrons return from the excited state to the ground state, they emit an amount of energy that is equal to the energy difference between the two levels
quantum mechanical model:
electrons do not travel in defined orbits but rather are localized in orbitals; a region of space around the nucleus
Heisenberg uncertainty principle
it is impossible to know both an electrons position and its momentum at exactly the same time
4 quantum numbers:
n- principle, describes average energy of shell
l- azimuthal, describes sub shells within a given principal energy level
ml- magnetic, specifies the particular orbital within a sub shell where an electron is likely found
ms- spin, indicates the spin orientation of an electron in an orbital
Hund’s rule
how electrons fill orbitals
sub shells with multiple orbitals fill electrons so that every orbital in a sub shell gets one electron before any of them gets a second
Paramagnetic vs diamagnetic
-have unpaired electrons that align with magnetic fields, attracting the material to a magnet
-have all paired electrons, repelled by magnets
Valence electrons:
electrons in the outermost shell available for interaction (bonding) with other atoms
