Module 1 Flashcards
refers to the structure of an atom comprising a nucleus
atomic structure
what is the center of the atom
nucleus
what atom is a positively charged
protons
an atom that is neutral charged
neutrons
the negatively charged particles
electrons
smallest atomic arrangement is
unit cell
plays an important role in determining the microstructure and behavior of a solid
atomic arrangement
are structures that range between 1 nm and 100 nm in at least one dimension
nanostructure
material structures seen at the micro level
microstructure
they are structures of an object, organism, or material as revealed by a microscope
microstructure
the structure of a material at a macroscopic level where the length scale is >100 um
macrostructure
what are the features that constitute macrostructure
PSIE
Porosity, Surface coatings, Internal microcracks, and external microcracks
composed of a nucleus surrounded by electrons
atom
it contains neutrons and positively charged protons and carries a net positive charge
nucleus
nucleus contains neutrons and positively charged protons and carries what charge?
a net positive charge
the negatively charged electrons are held to the nucleus by an?
electrostatic attraction
the charge of number of an atomic nucleus which is equal to the number of protons in each atom
Atomic number
equal to the total mass of the average number of protons and neutrons in atomic mass units, also the mass of the grams of the Avogadro’s constant
atomic mass
value of Avogadro’s constant
6.022 x 10^23 mol
formula in calculating the number of atoms
Number of atoms= (avogadro’s constant/ atomic mass of an element)
the energy level to which each electron belongs is identified by for quantum numbers
- principal quantum number (n)
- the azimuthal or secondary quantum number (l)
- the magnetic quantum number (m)
- the spin quantum number (ms)
is assigned integer values 1,2,3,4,5.. that refer to the quantum shell to which the electron belongs
principal quantum number (n)
a set of fixed energy levels to which electrons belong
quantum shell
a quantum number for an atomic orbital that determines its orbital angular momentum and describes the shape of the orbital
azimuthal quantum number (l)
it determines the number of energy levels in each quantum shell
azimuthal quantum number (l)
specifies the orientation in space of an orbital of a given energy (n) and shape (l). this number divides the subshell into individual orbitals which hold the electrons
magnetic quantum number (mi)
describes the intrinsic spin of an electron.
spin quantum number (ms)
for electron it has two possible values
ms= -1/2 and +1/2
states that two or more identical particles with half- integer spins cannot occupy the same quantum state within a quantum system simultaneously
pauli exclusion principle
a graphical device that predicts deviations from the expected ordering of the energy levels
Aufbau principle
electrons will occupy each orbital of a given energy level singly before the orbitals are doubly occupied
Hund’s rule
an electron in the outer shell associated with an atom
valence electron
describes the tendency for an atom to attract shared electrons when forming a chemical bond
electronegativity
the typical distance from the center of the nucleus to the outermost electron
atomic radius
the minimum energy required to remove the most loosely bound electron of an isolated gaseous atom
ionization energy
the ability of an atom to accept an electron and the energy change that results from adding an electron to a gaseous atom
electron affinity
Atomic radius_____ from left to right within a period. this is caused by the ____ in the number of protons and electrons across a period
decreases, increase
atomic radius______from top to bottom within a group. caused by electron shielding or principal quantum number, n.
increases
from ____to____ across a period of elements, electronegativity increases
left to right
from ___to___ down a group, electronegativity decreases
top to bottom
has the highest ionization energy of all elements
Helium
a metal that contains additions of one or more metals or non-metals
alloy
have good electrical and thermal conductivity
metals
have relatively high strength, high stiffness, ductility, and shock resistance
metals and alloys
can be defined as inorganic crystalline materials typically based on combinations of many elements.
ceramics
are plastics that are primarily based on carbon. have a very good strength-weight ratio, not suitable for use at high temperatures
polymers
are good electrical and thermal insulators
polymers
has electrical conductivity between that of ceramic insulators and metallic conductors
semiconductors
four types of chemical bonds
metallic bonds, covalent bonds, ionic bonds, van der waals bonds
a type of chemical bond formed between positively that donate their valence electrons to form a sea of electrons surrounding the atoms
metallic bond
refers to the ability of materials to be stretched or bent permanently without breaking
ductility
difference in electronegativity of ionic bond
> 2.0
difference in electronegativity of covalent bond
<1.7
difference in electronegativity of polar covalent bond
> 0.5
difference in electronegativity of non-polar covalent bond
<0.5
in this bond, one atom gives up its electron to the other atom and forms two ions with opposite charge
ionic bond
two atoms share two electrons if there difference in electronegativity is <1.7
covalent bond
difference in electronegativity >0.5
polar covalent bond
difference in electronegativity <0.5
non-polar covalent bond
a relatively weak attractive forces that act on neutral atoms and molecules and that arise because of the electric polarization
Van der Waals Force
types of van der waals interactions:
LDK
London forces, Debye interaction, and Keesom forces
if the interaction are between two dipoles that are induced in atoms or molecules
london forces
when an induced dipole interacts with a molecule that has a permanent dipole moment
debye interaction
if the interaction are between molecules that permanently polarized
Keesom force
the equilibrium distance between atoms is cause by a balance between repulsive and attractive forces
interatomic spacing
the energy required to create or break the bond
binding energy
the unit measurement of an objects or substance resistance to being deformed elastically when a stress is applied to it
modulus of elasticity
refers to the rate at which a material expands with increase in temperature
coefficient of thermal expansion
the maximum stress that can be applied before a material begins to change shape permanently
yield strength
the maximum stress that a material can withstand while being stretched or pulled before breaking
tensile strength
