MSE exam 2

s, p, d, f (directional or non directional, # of electrons)

s = non directional - 2

p = directional - 6

d = directional - 10

f = direction - 14

Short hand configuration

[Ar] 4s^_ 3d^_

Order orbitals are filled

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p

Fluorescence

Electrons absorb light, jump to higher state and quickly release energy as light when returning to ground state

Phosphorescence

Electrons absorb light, jump to higher state and release energy as light when returning to ground state (this takes longer)

Copper (Cu) & Chromium (Cr) electron configuratiohhh

Cu: $[\text{Ar}]\,4s^1 3d^{10}$ (Ground state)

Cu: $[\text{Ar}]\,4s^03d^{10}$ (Charged)

Cr: $[\text{Ar}]\,4s^1 3d^5$ (Ground state)

Cr: $[\text{Ar}]\,4s^03d^5$ (Charged)

Ionic bonds

One atoms transfers electron(s) to other atom (electrons not shared)

Covalent Bonds

Atoms share electrons (usually between non metals)

• strongly directional bonds

• Strong bond strength

• Mostly polymers & semiconductors

• Overlapping orbitals

Metallic bonds

Two positive ions share a sea of electrons (electrons shared)

• non directional

• Highly conductive

• Allows for plastic deformation

Van der Waals Bonds

• Weak attraction between partially + & - atoms (electrons not shared)

• Polymers and semi conductors

How is magnetic saturation determined

Number of unpaired electrons

The more unpaired the more magnetic saturation

Electronegativity

• Atoms ability to attract electrons to itself when forming bonds

• increases from bottom to top and left to right

what columns are

• alkali metals

• Alkaline metals

• Halogens

• Noble gases

• Transition metals

• Rare earth metals

• alkali metals: 1

• Alkaline metals: 2

• Halogens: 17

• Noble gases: 18

• Transition metals whole middle

• Rare earth metals: (57 - 71) and (Sc, 21) & (Y, 39)

A higher ionic charge means

• ionic bond (higher or lower)

• Bond energy (higher or lower)

• Melting point (higher or lower)

• Higher ionic bond

• Higher Bond energy

• Higher Melting point

Parts of force vs distance graph

• max

• Slope

• Equilibrium bond distance

• Equilibrium point

• max: max attractive force (peak of the curve)

• Slope: Stiffness (the steeper the stiffer)

• Equilibrium bond distance: distance from 0 to where all forces are equal)

• Equilibrium point: Where net force and attractive and repulsive forces are 0 (where graph crosses from negative to positive)

Parts of energy vs distance graph

• min

• Curve crosses x axis

• 0 to min

• min: equilibrium point

• Curve crosses x axis: potential energy = 0

• 0 to min: equilibrium distance

Higher enthalpy of fusion (higher or lower stiffness)

Higher stiffness

Bond energy equation (total bond energy)

E_total = -A/x + B/X^12

-Ax = attraction energy

B/x^12 =repulsive energy

A= attractive energy constant

B = Repulsive energy constant

x= distance between atoms

Identifying Stiffness

• Force vs Distance curve

• Energy vs distance curve

• Force vs Distance curve: the steeper the stiffer

• Energy vs distance curve: the narrower the stiffer

Identifying (Energy vs distance curve)

• Melting point

• Thermal expansion

• Melting point: the lower the bottom the higher the mp & fp

• Thermal expansion: the wider the curve the higher the CTE

Factors that affect density of a material

• Atomic mass

• Crystal Structure

• Pores in the material

Coordination number

Number of nearest neighboring atoms surrounding an atom

Crystal

A solid whose atoms are arranged in a repeating pattern

A grain

A single crystal within a polycrystalline

Hexagonal closed packing (HCP)

Stacking order

CN

Efficiency

Side lengths

Angles

Stacking order: ABABAB

CN: 12

Efficiency: 74%

Side lengths: a = b /= c

Angles: alpha = 120, beta = gamma = 90

Face centered cubic

Stacking order:

CN:

Efficiency:

Side lengths:

Angles:

Atoms per unit cell

Stacking order: ABCABCABC

CN: 12

Efficiency: 74%

Side lengths: a = b = c

Angles: alpha = beta = gamma = 90

Atoms per unit cell: 4

Rotational angle equation

360/n

Allowed rotational symmetries - degrees - crystal system

1 fold - 360 degrees - triclinic

2 fold - 180 degrees - Orthorhombic / monoclinic

3 fold - 120 degrees - Rhombohedral (trigonal)

4 fold - 90 degrees (pyrite) - Tetragonal / cubic

6 fold - 60 degrees (Amethyst) - Hexagonal

Angle betweeen sides

Alpha : b c

Beta : a c

Gamma : a b

Crystal system

Cubic

a = b = c

α = β = γ = 90

Hexagonal

a = b /= c

α = 120 β = γ = 90

Tetrahedral

a = b /= c

α = β = γ = 90

Orthorhombic

a /= b /= c

α = β = γ = 90

Rhombohedral (Trigonal )

a = b = c

α = β = γ /= 90

Monoclinic

a /= b /= c

α /= 90 β = γ = 90

Triclinic

a /= b /= c

α /= β /= γ

Lattice types

• Primitive : corners only

• Body centered: corners + middle

• Face centered: cornered + all 6 faces

• Base centered + top and bottom

14 Bravais Lattices

Cubic

Hexagonal

Tetrahedral

Orthorhombic

Rhombohedral

Monoclinic

Triclinic

Cubic: P, BC, FC

Hexagonal: P

Tetrahedral: P, BC

Orthorhombic: P, BC, BaC, FC

Rhombohedral: P

Monoclinic: P, BC

Triclinic: P

Molar mass to mass

Mass = (#atoms • molar mass)/ 6.022 × 10^23

Angstroms to cm

1 A = 1 x 10*-8 cm

1 A³ = 1 x 10^-24

Lattice

Points

Basis

Atoms at each point

All crystalline have 1 fold rotation symmetry

True