Gen Chemistry Ch. 1: Atomic Structure Flashcards
Proton
Positive charge, mass around 1 amu
Neutron
No charge, mass around 1 amu
Electron
Negative change, negligible mass
Nucleus of an atom
Contains the protons and neutrons, electrons move around the nucleus
Atomic number (Z)
Number of protons in a given element, unique identifier because elements defined by number of protons
Mass number (A)
Sum of an element’s protons and neutrons, can be different within an element because of isotopes
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 number of neutrons
Isotopes of hydrogen
Protium, deuterium, and tritium
Atomic weight
Weighted average of the naturally occurring isotopes of an element, listed by periodic table
Rutherford model
The atom has a dense, positively charged nucleus that makes up only a small fraction of the volume of the 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
Planck model
The energy difference between energy levels is called a quantum
Quanta
Discrete bundles of energy that are emitted as electromagnetic radiation from matter
Quantization
There is not an infinite range of energy levels available to the electron; electrons can exist only at certain energy levels
Atomic absorption spectrum
Unique to each element, 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 different between the two levels
Atomic emissions spectrum
Unique to each element, when electrons return from an excited state to the ground state, they emit an amount of energy that is exactly equal to the energy difference between the two levels, sometimes the EM energy emitted corresponds to a frequency in the visible light range
Quantum mechanical model
Electrons do not travel in defined orbits but rather are localized in orbitals
Orbital
A region of space around the nucleus defined by the probability of finding an electron in that region of space
Heisenberg uncertainty principle
It is impossible to know both an electron’s position and momentum exactly at the same time
Quantum numbers
Completely describe any electron in an atom
Four quantum numbers
n, l, ms, ml
Principal quantum number
n - described the average energy of a shell
Azimuthal quantum number
l - aka angular momentum quantum number, describes the subshells within a given principal energy level (s, p, d, or f), values range from 0 to n-1, s = 0, p=1, d = 2, f =3