Chemistry Atomic Structure

Chemistry :
Atomic Structure
Element
atom
smallest part of element
behaves like the element
unique
sub-atomic particles
NB relative scale.
very little mass or charge
M: Mass number
P + N
A: Atomic Number
P
E: Element
isotope
protons
same number
neutrons
different numbers
chemical properties
same
physical properties
slightly different
Relative Atomic Mass
Ar
The average mass of a mole of atoms
of an element on a scale where the mass
of a carbon atom is 12 units
average mass
1 mole
element
carbon 12 atom = 12 units
moles = mass/Ar
example
chlorine 2 isotopes : 75% Chlorine 35, 25% Chlorine 37. Ar= 35.5
Electrons
Configuration
shells
oxygen
8 electrons
arrangement 2,6
phosphorus
15 electrons
arrangement 2,8,5
chemcial properties
group 1 elements
outer shell
1 electron
elements
Lithium (2,1)
Sodium (2,8,1)
Potassium (2,8,8,1)
properties
highly reactive
metals
group 7 elements
Halogens
outer shell
7 electrons
elements
Flourine (2,7)
Chlorine (2,8,7)
Bromine (2,8,18,7)
Iodine (2.8.18.18.7)
properties
highly reactive
NON-metals
group 8 elements
Noble gases
outer shell
8 electons
filled
elements
helium (2)
neon (2.8)
argon (2.8.8)
krypton (2.8.18.8)
xenon (2.8.18.18.8)
properties
extremely stable
unreactive
Carbon Electronic Structure
Periodic Table
arrangement
chemical properties
physical properties
PERIODICITY
number of electrons in outer shell
increase to right, between periods
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