MPCSllthChemistryChs4-5vocab
Terms
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- atomic number
- the number of protons in the nucleus of an atom of an element
- cathode ray
- stream of electrons produced at the negative electrode (cathode) of a tube containing a gas at a low pressure
- neutron
- a subatomic particle with no charge and a mass of 1 amu; found in the nucleus of an atom
- isotopes
- atoms of the same element that have the same atomic number but different atomic masses due to a different number of neutrons
- wavelength
- the distance between adjacent crests of a wave
- nucleus
- the tiny, dense central portion of an atom, composed of protons and neutrons
- atom
- smallest particle of an element that retains its identity in a chemical reaction
- atomic orbital
- mathematical expression describing the probability of finding an electron at various locations; usually represented by the region of space around the nucleus where there is a high probability of finding an electron
- electromagnetic radiation
- energy waves that travel in a vacuum at a speed of 2.998 x 10^8 m/s; includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, x-rays, and gamma rays
- Hund's rule
- electrons occupy orbitals of the same energy in a way that makes the number or electrons with the same spin direction as large as possible
- aufbau principle
- rule that electrons must occupy the orbitals of lowest energy first
- quantum
- the amount of energy needed to move an electron from one energy level to another
- periodic table
- an arrangement of elements in which the elements are separated into groups based on a set of repeating properties
- hertz
- unit of frequency, equal to one cycle per second
- Dalton's Atomic Theory
- first to relate chemical changes to events at the atomic level
- amplitude
- the height of a wave's crest
- mass number
- total number of protons and neutrons in the nucleus of an atom
- electron configurations
- arrangement of electrons of an atom in its ground state into various orbitals around the nuclei of atoms
- atomic mass unit (amu)
- a unit of mass equal to one-twelfth the mass of a carbon-12 atom
- Heisenberg uncertainty principle
- it is impossible to know exactly both the velocity and the position of a particle at the same time
- atomic emission spectrum
- pattern formed when light passes through a prism or diffraction grating to separate it into the different frequencies of light it contains
- spectrum
- wavelenghts of visible light that are separated when a beam of light passes through a prism; range of wavelenghts of electromagnetic radiation
- group
- vertical column of elements in the periodic table; the constituent elements have similiar chemical and physical properties
- photons
- a quantum of light; a discrete bundle of electromagnetic energy that interacts with matter similarly to particles
- energy levels
- the specific energies an electron in an atom or other system can have
- frequency
- the number of wave cycles that pass a given point per unit of time; frequency and wavelength are inversely proportional to each other
- atomic mass
- the weighted average of the masses of the isotopes of an element
- ground state
- the lowest possible energy of an electron described by quantum mechanics
- period
- horizontal row of elements in the periodic table
- proton
- a positively charged subatomic particle found in the nucleus of an atom
- Pauli exclusion principle
- an atomic orbital may describe at most two electrons, each with opposite spin direction
- electron
- negatively charged subatomic particle
- quantum mechanical model
- the modern description, primarily mathematical, of the behavior of electrons in atoms