Presentation is loading. Please wait.

Presentation is loading. Please wait.

Atomic Structure.  Smallest particle of an element w/ properties of that element  About 90 natural elements  Combine to form compounds ◦ Atoms  elements.

Similar presentations


Presentation on theme: "Atomic Structure.  Smallest particle of an element w/ properties of that element  About 90 natural elements  Combine to form compounds ◦ Atoms  elements."— Presentation transcript:

1 Atomic Structure

2  Smallest particle of an element w/ properties of that element  About 90 natural elements  Combine to form compounds ◦ Atoms  elements  compounds

3  460 – 370 BC: Democritus ◦ “atomos” (indivisible & indestructible) ◦ Greeks believed in 4 basic elements ◦ Accepted for 2000 years

4  Law of Conservation of Matter ◦ Matter is neither created nor destroyed

5  Law of Definite Proportions ◦ A compound always contains elements in a certain, definite proportion & no other combinations ◦ Ex. H2OH2O  CO  HCl

6  Law of Multiple Proportions ◦ Elements may combine in more than one proportion forming different compounds ◦ Led to the atomic theory  1. all matter is composed of atoms which are indivisible  2. all atoms of the same element are alike, atoms of different elements are different

7  3. Compounds are formed when atoms of different elements combined in fixed proportions  4. Chemical reactions involve a rearrangement of atoms  Model:

8  Discovers proton using cathode ray tube & noticing that rays traveled in opposite direction of cathode (-)  Mass is 1840x’s that of an electron

9  Discovered electron using cathode ray tube where flow goes from cathode (-) to anode (+)  Millikan in 1916 found mass(1/1840 x’s mass of H atom) & charge(-1)  Model:

10

11  Discovers a condensed core w/ gold foil experiment  Called it the ‘nucleus’ & composed of protons & neutrons  Model known as “Nuclear Atom”  Model:

12

13  Discovers subatomic particle w/ no charge  aka Neutron  Mass nearly equal to proton (slightly larger)

14  Protons ◦ Positive ◦ In nucleus ◦ Mass = 1840 x’s an electron ◦ Same as atomic #  Electrons ◦ Negative ◦ Outside nucleus ◦ 1/1840 mass of proton  Neutrons ◦ Neutral ◦ In nucleus ◦ Almost the same as proton, slightly larger

15

16  Mass # = #protons + # neutrons  Mass # for element & # neutrons may vary  Ex. ◦ 14 C 6 p +, 8n o ◦ 12 C 6 p +, 6n o

17  Increase/decrease in # of electrons  In atom: ◦ Protons = electrons  Ex.  Na ◦ 11p +, 11e -  Na + ◦ 11p +, 10e -

18  Found using mass spectrometer  Based on average of relative abundance of isotopes of the element  Measured in amu’s (1/12 of a carbon atom)

19  Number of stable isotopes  % of each isotope  Mass of each isotope


Download ppt "Atomic Structure.  Smallest particle of an element w/ properties of that element  About 90 natural elements  Combine to form compounds ◦ Atoms  elements."

Similar presentations


Ads by Google