chem-- periodic table
Terms
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- Mendelecv
- orginized periodic table by atomic mass
- mosley
- organized periodic table by atomic number
- periodic law
- similiarities in elements are the result of the number of outermost valence electrons
- how much of the periodic table is metal
- 2/3
- structure
- small section called metalloids
- metalloids
-
elements with both metallic and non matallic properties
(B, Si, Ge, As, Sb, Te, Po)
*Po = raidoactive - all elements with atom numbers greater than 83 are...
- raidoactive isotopes
- trend
-
as you move left ---> to right you go from
Metal---> to metalloid ---> to non metal - groups
-
18 of them
vertical columns of elements with similar properties because they have the same number of valence electrons
AKA "Family" - group 1
-
alkali metals
- most raidoactive mentals
- do not exist free in nature
- hydrogen although in group 1 is NOT an alkali metal - Group 2
-
alkali earth metals
- very raidoactive metals
- do not exist free in nature - Group 13
-
- Boron = metalloid
- {Al - Te} Metals - group 14
- *Carbon* has allotropes
- allotropes
- any element which can exist in more than one form
- group 15
-
contains nitrogen-- tripple bond
- tripple bond makes nitrogen almost unreactive - group 16
-
halogens
- contains oxygen-- double bond
- double bond makes oxygen somewhat unreactive - oxygen- allotropes
-
has 2 allotropes
1= O2 (Gas)
2= O3 (gas) = ozone - group 17
-
halogens
* most reactive non-metals
* do not exist free in nature
- contains (4) of the (7) HOFBrINCl2 --diatomic molecules
H²- (g)
O²- (g)
F²- (g)
Br²-(l)
I²- (s)
N²- (g)
Cl²-(g) - Group 18
-
noble/ inert gases
- monoatomic molecules
-unreactive
-some rare Xe & Kr compounds do exist
(He, Ne, Ar, Kr, Xe, Rn) - periods
-
7 of them
horizontal rows of elements - transition metals
-
groups 3-11
periods 4-7
- some what unreactive metals
- some transition metals can form colored solutions or solids (C4 = Blue) - lanthanide series
-
(period 6) (57-71)(Can be found naturally on earth)
AKA:
Rare earth elements or
inner-transition elements
* only one element in the series is raidoactive* - actinide series
-
(period 7) (89-103)
- all are raidoactive
- not found in nature - symbols
- either single uppercase letter of an uppercase letter with and lowercase letter
- rutherford
- - credited with the discovery of the atomic nucleus
- rutherford's gold (Au) foil experiment
- rutherford "bombarded" a think gold foil with (alpha)particles which are positivly charged
-
What does it mean??:
many particles moved passed the gold foil - the atom is mostly EMPTY space
-
What does it mean??:
some of the (+)alpha particles deflected back off the foil - the Nucleus of an atom is (+) charged and that most of the mass of an atom is in the nucleus
- planets revolve around the sun like _____ revolves around the _____
- ELECTRONS revolves around the NUCLEUS
- electrons
- negative particle that is found OUTSIDE ther nucleus and has a mass of zero
- nucleus
-
AKA: Nuclide or Nucleons
Protons and neutrons - proton
-
symbol: P= :H (each . = 1)
charge: +1
Mass: 1g
Location: inside nucleus - neutron
-
symbol: n= ;1 (.=1 ,=0)
charge: +1
Mass:1g
Location: inside nucleus - electron
-
symbol: eˉ¹= ;e =ß
(.=1 ,=0)(ß= beta)
charge: -1
Mass: 0
Location: outside nucleus - atomic number of protons
- never changes
- neutral atom
- # of particles = # of electrons
- ion
- an atom with an electron charge
- (+) Ion
-
AKA: Cation
- an atom that has lost electrons - (-) Ion
-
AKA: Anion
- an atom that has gained electrons - protons + neutrons =
- mass number
- symbol formate
-
top left corner = mass #
top right corned = charge
middle = element symbol
bottom left = atomic number - isotope
- an atom with the same number of protons (atomic #) but a different number of neutrons (mass #)and thus a different mass
- Mass Number
- NOT EQUAL TO ATOMIC MASS!!
- atomic mass
- the weighted average, by mass of all know isotopes for a given element
- atomic mass is based on...
- the relative % abundance of each isotope in the element
- atomic mass unit (amu)
-
a unit of mass based on the carbon- 12 isotope = 12.000 amu
* 1 amu = 1/12th mass of carbon-12 * - atomic mass formula
- atomic mass= (% abundance)(mass of isotope) + (% abundance)(mass of isotope)
-
Boron has (2) isotopes.
B-10 has a mass of 10.013 amu and % abundance of 19.9% B-11 has a mass of 11.0093 amu and a % abundance of 80.1%what is the atomic mass of boron? -
atomic mass= (% abundance)(mass of isotope) + (% abundance)(mass of isotope)
X = (.199)(10.013) + (.801)(11.0093)
X= 1.9925 + 8.8184
Atomic mass = 10.8109 - another name for nucleus
- nuclide
- natural radioactivity
- The spontaneous (decay) disintegration of “unstable†nuclei to “mere stable†nuclei through a transmutation of one element into another.
- transmutation
- one element change into another by releasing a sub atomic particle or proton of radiant energy
- why does transmutation occur?
- each radioactive isotope seeks to have a neutron proton ration of about 1:1 (n:p)
- lead block test
- separation of particles by magnetic and electric fields
- natural radioactive decay: General form
-
A ---> B + C
A= unstable radioisotope
B= stable isotope
C= subatomic particle - law of conservation of charge and mass
- in nuclear process BOTH charge and mass are conserved
- Alpha decay
-
releases an alpha particle
*mass # goes down by 4 and atomic # goes down by 2* - name the types of natural radioactive decay
-
1- general
2- alpha
3- beta +
4- beta - - during alpha decay what is the change, if any, in mass # and/or Atomic #?
-
Mass #- goes DOWN 4
Atomic # goes DOWN 2 - beta (-) decay
-
releases a ß- = -1 e
(Beta negative = electron) - during Beta (-) decay what is the change, if any, in mass # and/or Atomic #?
-
Mass #- remains the same
Atomic #- goes UP by 1 - Beta (+) decay
-
releases the positron
(+1e) - during Beta (+) decay what is the change, if any, in mass # and/or Atomic #?
-
Mass #- remains the same
Atomic #- goes DOWN 1 -
artificial transmutation
(General form- formula) -
General form:
A+B --> C+D
A= target nucleus
B= bombarding particles
C= new isotope
D= subatomic particles -
artifical transmutation
(definition) - rediaisotopes are made in a lab when a target nucleus is bombarded with a high energy particle (proton, electron, neutron, positron)
- Particle accelerator
- mechines that speed up CHARGED particles so theat they can penetrate the target nucleus (series of electromagnetic fields)
- HALF LIFE of radioactive material
- the time it takes for a radioactive substance to decay to 1/2 its original mass
- does the half life ever change?
- NO!!! the half life NEVER changes- its uneffected by temperature, pressure or volume
- half life periods =
-
total time
----------- (over)
1/2 life - use of radioisotopes
-
1- chemical tracers : C-12
2- Medicine- short 1/2 life so that it will leave the body quickly
3- industry- to radiate food, to preserve it
4- geology/ archaeology- C-14/ U-238 ~ fossil dating - definition of Nuclear Energy
- the conversion of a small amount of mass into radiant energy
- nuclear energy
-
~the starting materials (reactants) lose some mass and produce products that are more stable and lighter
~Enormous amounts of energy are produced - eintein called this the "Mass defect"
-
E= MC²
E= energy
M= mass
C= speed of light - the two processes of nuclear energy
- nuclear fission and nuclear fusion
- definition of fission recations
- the "splitting" of HEAVY atomic nuclei into smaller, more stable "fission- fragments" and the release of a lot of energy
- process of fission reactions
- neutrons are "captured" by a target nucleus breaking a LARGE nucleus into smaller isotopes
- fission reactions result in
-
1- energy
2- more radioisotopes
3- more neutrons - what is fission used for
- to produce electricity, radioisotopes used in medicein, and industry/research
- benefits of nuclear fission
-
A- efficient source of energy without the air pollution associated with the burning of fossil fuels
B- produces useful radioisotopes used in medicine and research - Problems with nuclear fission
-
A- Meltdown/Nuclear accident
B- coolant H2O is returned to its source over-heated killing fish and other animals
C- the productiton of toxic raidoactive waste with long 1/2 lifes - fission fuel cells
-
U-235
U-233
Pu-239 (breeder reactor)
** U-238, which comprises more than 99% of all natural Uranium is NOT fissionable fuel** - raidoactive waste with cause by fission
- its a problem becaus of its long 1/2 life and storage issues
- nuclear fusion
- the joining of (2) "light nuclei" to form a more stable and heavier nucleus
- nuclear fusion ________ energy compared to nuclear fission
-
~*Produces greater*~
nuclear fusion PRODUCES GREATER energy compared to nuclear fission - why is it difficult for fusion to occur?
- A- b/c of the (+) charge of the small nuclei, a strong repulsive force exists between the nuclei making it difficult for them to react
- how do you make fusion happen?
-
you need high temperatures
AKA: thermonuclear reactions - benefits of fusion
- could provide an unlimited source of energy without the pollution associated with the burning of fossil fuels and nuclear fission