University:
Eastern Kentucky University
Course:
CHE 111 | General Chemistry
Academic year:

2024
Views:

169

Pages:

8
Author:

Alma Stephenson

HISTORY OF ATOMIC THEORY Democritus - 500 BC Idea - everything is made of atoms *invisible + indivisible spheres of matter ATOM - smallest particle of an element with characteristics of that element ↑ consist of a nucleus (holds protons & neutrons) → electrons in empty space around nucleus Neutron (no charge) Proton (+) Electron (-) Nucleus MASS OF AN ATOM (Ch 4) *1 amu = atomic mass unit *1 amu = 1 Dalton (Da) *electrons NOT included in mass b/c so small mass # = NUMBER OF PROTONS + NEUTRONS ↑ Mass of NUCLEUS (# of particles) neutrons = mass number - atomic # John Dalton's ATOMIC THEORY all matter is made from atoms all atoms of a given element are same & different from atoms of other elements atoms of 2 or more elements combine to form compounds chemical reaction involves rearrangement, separation, combination of atoms *Atoms are neither created or destroyed dynamic particles (+) (+) positive charges repel (-) (-) negative charges repel (+) (-) unlike charges attract *neutral atoms - net charge = 0 atomic # = 11 of protons NA of electrons 35.45 ↑ atomic mass atoms of the same ciement il different mass #s Same # of protons but diff # of neutrons distinguished by atomic symbols ATOMIC MASS neighted average of all naturally occuring Isotopes of an element 17 CI 35.45 aromic mass (amu). Atomic Symbol Mass (amu) Percent Abundance 34.97x 76.76 100 36.97x 24.24 100 Atomic mass of Cl Isotope of Magresivm, Mg-24 mass # 24 Mg 12 aromic "use/ abundance of each isorope multiply the abundanu by armu Of isotope sum all masses of isotopes Contribution to the Atomic Mass 26.49 amu 8. 062 ama 35.45 amu (weighted average mass) ELECTROMAGNETH POIATION consists of energy particles that move as waves of energy Navelength-distance between peaks high energy diemen Shorter wavelengths lon energy maintien longer wavelengths ATOMIC SPECTRUM light from heated element Prism distinct lines of color svery cloment him wiive Specsem ELECTRON ENERGY LEVELS lines in atomic spectrum associated with changes in energies of electrons in energy al valve itn fatener away from Avedis energy of electron quantized can only have specific energy valves electrons wil same energy grouped together (prinuple quantum numbers) Celeverent con any have mergy of 1 trergy level in arom