Chemistry- Atom History & Structure Flashcards
(34 cards)
1
Q
Law of Conservation of Mass
A
- Lavoisier
- mass is neither created nor destroyed
- mass of reactants = mass of products
2
Q
Law of Definite Proportion
A
- Proust
- a given compound always contains exactly the same proportion of elements by mass
- ex. ALL water will be 11.1% hydrogen and 88.9% oxygen
3
Q
Law of Multiple Proportion
A
- Dalton
- the masses of one element that combine with a fixed mass of the other element form simple whole number ratios
- ex. SO2 and SO3 (oxygen- 2:3, S-constant)
4
Q
Continuous Theory
A
- Plato and Aristotle
- solid body and be divided and subdivided into smaller pieces without limit
5
Q
Discontinuous Theory
A
- Democritis
- matter CAN NOT be divided into smaller and smaller pieces forever
- ATOMAS: indivisible pieces of matter
- all matter is made up of tiny particles
6
Q
Dalton (1803)
A
- elements are composed of INDIVISIBLE, INDESTRUCTIBLE atoms
- all atoms of an element are IDENTICAL
- compounds form by joining 2 or more elements
- the atoms themselves ARE NOT CHANGED in a chemical reaction, they are reorganized
7
Q
Billiard Ball Model
A
- Dalton
- just a circle
- missing subatomic particles (neutrons, protons, electrons)
8
Q
J. J. Thomson (1897)
A
- worked with cathode ray tubes (passed electrical currents through gas)
- observed negatively charged particles and said they came from the gas
- discovered the ELECTRON and the charge to mass ratio of electron (e/m ratio)
9
Q
Plum Pudding Model
A
- Thomson
- atom is positive
- negatively charged electrons are scattered throughout (like raisins)
10
Q
Robert Milikan (1909)
A
- oil drop experiment
- found magnitude for the charge of electron to be 1.6 X 10^-19
- used e/m ratio to find mass
11
Q
Ernest Rutherford (1911)
A
- gold foil experiment
- bombarded gold foil with alpha (+ charged) particles
- was trying to confirm Thomson’s Plum Pudding Model, particles were all supposed to go through
12
Q
Gold Foil Experiment
A
- some alpha particles bounced back while others passed through
- most of the atom is empty space
- there is a small, dense, positively charged mass at the center of the atom (nucleus)
- atom has electron, proton, neutrons
13
Q
Neil Bohr (1913)
A
- planetary model
- since energy is quantized, there are specific locations at which electrons can exist
- called shells k (kurtz-first), L, M, N
- shells now called energy levels (where electrons move in, don’t lose energy until they move to another shell)
14
Q
Earliest to Latest Models
A
Hard-sphere –> electron shell –> wave mechanical
15
Q
Proton
A
- +1 charge
- 1 u (mass)
16
Q
Neutron
A
- 0 charge
- 1 u (mass)
17
Q
Electron
A
- -1 charge
- 0 u (mass)
18
Q
1 u (unified atomic mass unit)
A
1.6605 X 10^-27 kg
19
Q
Nucleus
A
contains protons and neutrons
20
Q
Atomic mass
A
- mass of the atom (P+N)
- weighted average of the masses of all the isotopes of an element
21
Q
Atomic Number
A
- number of protons in the nucleus (identifies the element)
- number of proton = number of electron
22
Q
Valence Shell
A
outermost shell
23
Q
Valence electrons
A
electrons present in the outermost shell
24
Q
Octet Rule
A
the outermost shell can not have more than 8 electrons
25
isotope
atoms of an element that have the same number of protons but a different number of neutrons OR elements with the same atomic number but different mass number
26
Ion
an atom that has a positive or negative charge because it has lost or gained an electron
27
caTion
- atom that lost electrons, now POSITIVE
- occurs with metals
- add "ion" to the end of the element
28
anion
- atom that gained electrons, now NEGATIVE
- occurs with nonmetals
- add "ide" to the end of the element (ex. fluoride)
29
Metals on Periodic Table
- to the left of the staircase
| - all metals are solids EXCEPT mercury (Hg)
30
Nonmetals on Periodic Table
to the right of the staircase (non malleable and non ductile)
31
Metalloids on Periodic Table
above or below the staircase
32
How to calculate atomic masses
- needed average mass of the object
- need to change the % abundance (out of 100) to relative abundance (out of 1)
- elements occur in nature as mixtures of isotopes
33
3 isotopes of Hydrogen
- H-1 (frotum) NO NEUTRONS
- H-2 (deuterium)
- H-3 (tritum)
34
kernal
atom - valence shell
