Metal Structure & Crystallization Flashcards
All matter is considered to be composed of unit substances known as
chemical elements
tiny particles of negative electricity
electrons
particles of positive electricity
protons
electrically neutral particles
neutrons
discovered that cathode rays could turn a small paddle wheel paced in the tube would cast a shadow of any solid object placed in their path which possessed negative charges
William Crooks
determined that the particles of which the rays were composed were travelling at high speeds and that each one had the mass of about 1/1800 of the hydrogen atom.
JJ Thomson
bombarded light elements with high speed alpha particles and emitted positively charged particles almost identical to the mass of the hydrogen
Ernest Rutherford
first concepted the atomic structure that met with wide acceptance
Gilbert Lewis and Irving Langmuir
bombarded beryllium with alpha particles resulted in the third kind of emission called the neutron
Chadwick
tabulated the periodic table or periodic classification of elements due to the similarities of physical and chemical properties of certain elements.
Dmitri Mendeleev
supplied by a proton or a neutron
Atomic mass/wt
indicates the number of protons
Atomic number
also indicates the number of electrons because an atom has to be electrically neutral
Atomic Number
The electrons spinning on their own axes as they rotate around the nucleus, are arranged in …
definite shells
The maximum number of electrons that can fit in each shell is
2n^2
In an atom or molecule, no two electrons can have the same four electronic quantum numbers and the two electrons must have opposing spins
Pauli Exclusion Principle:
principal quantum number related to the total energy of the electron in a particular state (1, 2, 3)
n
second quantum number which is a measure of the angular momentum of the electron (0 to n-1)
l
component of the angular momentum in a specified direction (0, +1, -1)
m1
spin of the electron on its own axis (+/- ½)
ms
electrons in the unfilled shells and are largely responsible for the behavior of the elements
valence electrons
stable group that shows very little activity wherein the 8 electrons filled the subshells
inert gases
distinguished by several characteristics
a) in the solid state, they exist in the form of crystals
b) they have relatively high thermal and electrical conductivity
c) they have the ability to be deformed plastically
d) they have relatively high reflectivity of light
Metal
have some conductivity but little or no plasticity (C, B, Si)
Metalloids
the remaining elements
Nonmetals
transfer of electrons
ionic bond
sharing of electrons
covalent bond
each of the atoms of the metal contributes its valence electrons to the formation of a negative electron “cloud”
metallic bond
when atoms are brought close together, there is a separation of the centers of positive and negative charges resulting to a weak attractive forces
Van der Waals Forces
Metals are _______ referred in these materials as grains which, in order to examine its range of magnification, falls in the category of a class known as ______________.
polycrystalline, microstructure
the basic structure inside the grains which are the atomic arrangements inside the crystals.
Crystal structure
the distance between center of the spheres if the atoms are visualized as spheres just touching at equilibrium
Atomic diameter
