atoms Flashcards
(22 cards)
atom
smallest piece of matter
nucleus
positively charged center of the atom
protons
particles with electrical charge of 1+
neutrons
neutral particles
electrons
particle with electrical charge of 1-
quarks
smaller particles that make up neutrons and protons
democritus
first person to propose the ideas of everything is made of up atoms
Joseph thomson
he thought electrons were evenly embedded throughout a positively charged sphere
John dalton
he was able to offer proof that atoms exist
Ernest rutherford
though that almost all the mass of an atom and its positive charges were concentrated in a central atomic nucleus surrounded by neutrons
Niels bohr
hypothesized that electrons traveled in a fixed orbit around the atoms nucleus
electron cloud
area around the nucleus of an atom where the electrons are most likely found
atomic number
number of protons in an atom is equal to a number
mass number
the sum of the number of protons and the number of neutrons in the nucleus of an atom
isotopes
atoms of the same element that have different numbers of neutrons
average atomic mass
the weighted average mass of the mix of its isotopes
periodic table
arrangements of elements
Dmitri mendeleev
the creator of the periodic table
Henry moseley
changed the arrangment of the periodic table based on their increasing atomic numbers
groups
the vertical columns in the periodic table
electron dot diagram
uses the symbol of the elements and dots to represent the electrons in the outer energy level
periods
horizontal rows on periodic table
