Atom
The smallest particle of an element that retains its identity in a chemical reaction
Democritus
Greek philosopher (460-370 BC) believed that atoms were indivisible and indestructible
Dalton's Atomic Theory
1) All elements are composed of tiny indivisible particles called atoms
2) Atoms of the same element are identical.The atoms of any one element are different from those of any other element
3) Atoms of different elements can physically mix together or can
Scanning tunneling microscope
despite their small size, individual atoms are observable with instruments such as this
Electrons
Negatively charged subatomic particles
Cathode Ray
A stream of electrons produced at the negative electrode of a tube containing a gas at low pressure
Protons
Positively charged subatomic particles
Neutrons
Subatomic particle with no charge but with a mass nearly equal to that of a proton
Nucleus
the tiny central core of an atom and is composed of protons and neutrons
Atomic Number
The number of protons in the nucleus of an atom of that element
Mass Number
the total number of protons and neutrons in an atom
Number of neutrons
Mass number - atomic number = ?
Isotopes
Atoms that have the same number of protons but different numbers of neutrons
Atomic Mass Unit (amu)
A unit of mass equal to one-twelfth the mass of a carbon- 12 atom
Atomic Mass
A weighted average mass of the atoms in a naturally occurring sample of the element
Calculate Atomic Mass
mass of ea isotope X natural abundance (as a decimal), then add the products
Periodic table
An arrangement of elements in which the elements are separated into groups based on a set of repeating properties
Period
Each horizontal row of the periodic table
Group (family)
Each vertical column of the periodic table