How can we help?

You can also find more resources in our Help Center.

23 terms

Chemistry Test 3

Chapters 4 & 10
STUDY
PLAY
Democritus
Theorized:
1) matter is not infinitely divisible
2) matter is composed to tiny particles called "atomos"
3) atoms cannot be created, destroyed, or ?
Aristotle
Theorized:
1) empty space does not exist
2) matter is made up of earth, fire, air, or water
Dalton
Theorized:
1) all matter is composed of extremely small, indivisible, and indestructible particles called atoms (rejected- divided into electron, neutron, proton)
2) atoms of a given element are identical in size, mass, and chemical properties (rejected- isotopes)
3) atoms of a specific element are different from those of another element
4) atoms cannot be created or destroyed (law of conservation of mass)
5) different atoms combine in simple whole number ratios to form chemical compounds (law of definite proportions)
6) in chemical reactions, oms are combined, separated, or rearranged
Dalton's atomic model
cannonball model
Atom
the smallest particle of an element that retains the chemical properties of that element
Nucleus
small region at the center of the atom that contains proton(s) and neutron(s)
Electron cloud / shell
a relatively large region surrounding the nucleus occupied by negatively charged particles
J.J. Thompson
concluded that all cathode rays are composed of identical, negatively charged particles
J.J. Thompson's atomic model
plum pudding model
Robert A. Millikan
discovered that the electron has almost no mass
Ernest Rutherford
Gold Foil Experiment conclusions:
1) atom is mostly empty space
2) there is a tiny, dense center of a particle that is positively charged
James Chadwick
discovered the neutron
Intra-nuclear forces
forces that old the nuclear particles together
Niels Bohr
believed the electrons travel on fixed orbits around the nucleus similar to how our planets orbit the sun
Niels Bohr's atomic model
Planetary model
atomic number
number of protons in an atom's nucleus
isotopes
atoms of the same element that have different masses because they have different numbers of neutrons
mass number
total number of protons and neutrons in the nucleus of an isotope
nuclide
the general tern for any isotope of any element
amu
atomic mass unit
average atomic mass
the weighted average of all known isotopes of an element
Avogadro's number
6.02 x 10²³
mole (mol)
the SI base unit for the amount of a substance