Chapter 2 Atoms, Elements, and The Periodic Table Flashcards
Metals
Shiny, good conductors of heat and electricity, malleable
Metalloids
Intermediate properties between metals and nonmetals.
Non-Metals
Poor conductors of heat and electricity, brittle
Ions
Atoms that have either lost or gained electrons
isotopes
Atoms of the same element that have different numbers of neutrons, and therefore different
masses
Atomic mass
The average mass of the isotopes that compose a particular element
The law of definite proportions (AKA: the law of constant composition)
All samples of a given
compound have the same proportions of their constituent elements
Dalton’s atomic theory
The main point of Dalton’s atomic theory is that matter is composed of tiny,
indestructible particles called atoms.
Plum pudding model of the atom
A model of the atom that views atoms as electrons embedded in a
sphere of positive charge
Ernest Rutherford’s gold foil experiment
An experiment in which α-particles were fired at an ultra-
thin piece of gold foil. Some of the α-particles were deflected, indicating that the plum pudding model of
the atom needed to be revised
Nuclear model of the atom
Model of the atom in which most of the atom’s mass, and all of its positive
charge, is concentrated in a small area called the nucleus. The nucleus us surrounded by a negatively-
charged electron cloud
Why did the discovery and characterization of electrons show that Dalton’s atomic theory needed to be
revised?
Atoms are no longer the smallest particle
T/F Atoms are mostly empty space
true
mass number
total number of protons and nuetrons in nuclues
