Chapter 2 Vocabulary
Experiments by Thomson
-Thomson found that cathode rays were attracted toward the positive electrode of an external electric field -Thomson found that cathode rays were deflected away from the negative end of an external magnetic field
atomic mass
-atomic mass is found on the periodic table for each element -the units used for atomic masses are amu
Bohr's theory of an atom
-electrons only occupy allowed energy levels -energy differences between levels can be calculated from the wavelength of light emitted
speed of light
3.0 x 10^8 m/s
nucleus
a small, dense, positively charged region in the center of an atom
electron
a subatomic particle that has a negative charge
proton
a subatomic particle that has a positive charge and that is found in the nucleus of an atom
neutron
a subatomic particle that has no charge and that is found in the nucleus of an atom
isotopes
atoms of the same element having different masses because they contain different numbers of neutrons
Dalton's atomic theory stated that all matter consist of tiny particles ___. When these tiny particles of different elements combine in simple whole-number ratios, they form ___.
atoms, compounds
from Geiger's experiments, Rutherford concluded that the atom contains a small, extremely dense region in which most of the atom's ___ is concentrated. He called this central region the ___ of the atom.
electrons, mass
what does it mean for energy to be quantized?
energy can have certain values but cannot have amounts between those values
energy levels
energy can have certain values but cannot have amounts between those values (quantization of energy)
atomic number
equal to the number of protons in the atom
mass number
equal to the sum of the number of protons
electromagnetic radiation
light
The modern __ law states that the physical and chemical properties of the elements display a certain periodicity related to their atomic ___.
periodic, number
An atomic orbital represents the ___ of finding a(n) ___ in a region of space.
probability, electron
wavelength
the distance between identical points on two successive waves
periodic law
the elements if arrange according to their atomic weights (masses), show a distinct periodicity (regular variations) of their properties
Dalton's Theory
the first experimentalist based theory of atomic structure
atomic orbital
the probability of finding an electron in a region of space within the principal energy level
atom
the smallest unit an element that retains the chemical properties of that element
atomic mass
the weighted average of the masses of each isotope that makes up the element
excited state
when the electron absorbs energy and is promoted to a higher state
ground state
when the electron of the atom are in the lowest possible energy levels
relaxation
when the electron spontaneously emits energy in the form of a photon of light of the exact energy necessary to return to the ground state