Chapter 2 Flashcards
Started the modern era of chemistry
John Dalton
Dalton’s Atomic Theory
- Elements are comprised of individually building blocks called atoms.
- Compounds are composed of more than one element.
- Chemical reactions rearrange atoms in chemical compounds; they do not create or destroy matter (atoms).
Atoms are alike in (1) _______, (2) ________, and (3) ________.
(1) size
(2) mass
(3) chemical properties
Law of Definite Proportions
elements combine in only one ratio
Example: NaCl, MgBr2, CaO
Law of Multiple Proportions
elements can combine in different ratios
Example: CuCl, CuCl2, CuCl3
Most basic unit of an element
Atom
Used cathode tube to discover the nature of the electron, led to the “Plum Pudding Model”
JJ Thompson
The “Plum Pudding Model” was disproved by which experiment?
Rutherford’s Gold Foil Experiment
Who proved the neutron?
James Chadwick
Cation
Lost electrons (Resulting charge became more positive. Think: cats have paws)
Anion
Gained electrons (Resulting charge became more negative.)
Isotope
same number of protons and electrons but a different number of neutrons
Average Atomic Mass
masses of the elements are determined by their natural abundances
1 amu = ______________
1/12th of a Carbon-12 atom
Ion
charged atom or group of atoms
