Ch. 1: Atomic Structure Flashcards
Proton
Positive charge and mass around 1 amu; charge of fundamental unit of charge (e= 1.6*10^-19 C)
Neutron
No charge and mass around 1 amu, mass only slightly larger than proton
Electron
Negative charge (equal magnitude of proton) and negligible mass
Nucleus
Contains the protons and neutrons, while the electrons move around the nucleus
Atomic Number
Number of protons in a given element, unique identifier for each element
Mass Number
Sum of an element’s protons and neutrons
Cation
Positively charged atom
Anion
negatively charged atom
Atomic mass
Essentially equal to the mass number, the sum of an element’s protons and neutrons
Isotopes
Atoms of a given element (same atomic number) that have different mass numbers. Differ in the number of neutrons
Isotope Identification
The element followed by the mass number (ex: carbon-12, carbon-13)
3 Isotopes of Hydrogen
Protium, deuterium, and tritium
Atomic Weight
Weighted average of the naturally occurring isotopes of an element. The periodic table lists atomic weights, not atomic masses
Rutherford
Postulated that the atom had a dense, positively charged nucleus that made up only a small fraction of the volume of the atom with gold foil experiment
Bohr Model of the Atom
Dense, positively charged nucleus surrounded by electrons revolving around the nucleus in orbits with distinct energy levels
Quantum
Energy diff between energy levels, first described by Planck
Quantization
There is not an infinite range of energy levels available to an electron; electrons can exist only at certain energy levels. The energy of an electron increases the farther it is from the nucleus
Planck relation
E=hf; E is the energy of a quantum, h is planck’s constant, and f is frequency of radiation
Atomic Absorption Spectrum
Unique; for an electron to jump from a lower energy level to a higher one, it must absorb an amount of energy precisely 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 amound of energy that is exactly equal to the energy diff between the two levels; every element has a characteristic atomic emission spectrum and sometimes the electromagnetic energy emitted corresponds to a frequency in the visible light range
Quantum Mechanical Model
Posits that electrons do not travel in defined orbits but rather are localized in orbitals
Orbital
Region of space around the nucleus defined by the probability of finding an electron in that region of space
Heisenberg Uncertainty Principle
States that it is impossible to know both an electron’s position and its momentum exactly at the same time
Quantum numbers:
4, completely describe any electron in an atom; according to pauli exclusion principle no 2 electrons in a given atom can possess the same set of 4 quantum numbers
Principle Quantum Number
n, describes the averege energy of a shell; energy diff from one shell to the next is a function of (1/ni^2)-(1/nf^2)
Azimuthal Quantum Number
l, describes the subshells within a given principle energy level (s, p, d, f)– spectroscopic notation refers to 1s^2 2s^2 sp^6 etc notation
Magnetic Quantum Number ml
Specifies the particular orbital within a subshel where an electron is likely to be found at a given moment in time (-l to +l)
Spin Quantum Number (ms)
Indicates the spin orientation (+ or - ½) of an electron in an orbital
Electron Configuration
Uses spectroscopic notation (combining the n and l values as a number and letter, respectively) to designate the location of electrons
n+l Rule
Electrons fill the principle energy levels and subshells according to increasing energy , which can be determined by the n+l rule
Hund’s Rule
electrons fill orbitals according to Hund’s rule, which states that subshells w multiple orbitals (p, d, and f) fill electrons so that every orbital in a subshell gets one electron before any of them gets a second
Paramagnetic
Have unpaired electrons that align with magnetic fields, attracting the material to a magnet
Diamagnetic
Have all paired electrons, which cannot easily be realigned; they are repelled by magnets
Valence Electrons:
Those electrons in the outermost shell available for interaction (bonding) with other atoms
Representative Element VEs
Groups 1, 2, and 13-18, the valence electrons are found in s- and/or p-orbitals
Transition elements
Valence electrons are found in s- and either d- or f- orbitals
Octet Rule
Many atoms interact with other atoms to form bonds that complete an octet in the valence shell
