Scientists
The man who first suggested that atoms existed
Democritus
Has a positive charge
proton
the atom proposed by J. J. Thomson in 1904
Plum Pudding
states that when electrons occupy orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with parallel spins
hunds rule
Atoms that have the same number of protons but different numbers of neutrons
isotopes
He discovered electrons in 1897
JJ Thomson
Has a negative charge
an atomic structure proposed by Rutherford with a dense, positive center called a nucleus surrounded by negative electrons orbiting like planets around the sun
Planetary Model
states that electrons must fill the lowest energy orbitals first
Aufbau Principle
If an atom has a mass number of 19 and atomic number of 9, how many protons, neutrons, and electrons does it contain?
9 protons, 10 neutrons, and 9 electrons
He found the quantity of charge of an electron
Robert Millikan
Has no charge
neutron
most accurate understanding of atomic structure that describes electrons using probability waves rather than fixed, circular orbits.
Quantum Mechanical Model
This rule specifies that no two electrons in an atom can have the exact same four quantum numbers.
Pauli Exclusion
An atom is neutral when the number of protons equals the number of ________________.
electrons
He found evidence of a positive charged particle
is best defined as the number of protons and neutrons in the nucleus of an atom
mass number
describes a tiny, dense, positively charged center called the nucleus, which is surrounded by much lighter, negatively charged electrons
Nuclear model
All elements are composed of tiny indivisible particles called atoms.This is a part of who's atomic theory?
Dalton
AMU stands for:
atomic mass unit
He found that cathode rays have a negative electrical charge because they are attracted to positively charged metal plates
JJ Thomson
True or false. The mass of a single proton or neutron is approximately 4 amu
False, it is 1 amu
True or False. Erwin Schrodinger founded the most current model of the atom.
true
Which part of Daltons theory has since been proven incorrect?
atoms are now known to be divisible
A stream of electrons produced at the negative electrode (cathode) of a tube containing a gas at low pressure
cathode rays