Comprehensive Engineering Chemistry Master Reviewer

Comprehensive vocabulary flashcards covering metals and crystal structures, polymer classifications and architectures, atmospheric layers and degradation mechanisms, soil chemistry and horizons, and chemical hazard classifications under RA 6969.

Metallic Bonding

An atomic-scale bonding mechanism consisting of positive metal ions (cations) fixed in a rigid crystal lattice surrounded by a delocalized "sea of electrons" that move freely throughout the structure.

Malleability

The ability of a material to undergo extensive plastic deformation under compressive stress (such as hammering or rolling into sheets), exemplified by gold ($\text{Au}$), where $1\,\text{g}$ can be beaten into a $1\,\text{m}^2$ sheet.

Ductility

The capacity of a material to sustain plastic deformation under tensile load before fracturing (drawing into fine wire), highly exhibited by platinum and silver ($100\,\text{g}\;\text{Ag}$ can yield $\sim 200\,\text{m}$ of wire).

Ferrous Metals

Metals containing iron ($\text{Fe}$) as the primary base constituent ($> 50\%$), typically heavy with high volumetric density ($7.8 - 7.87\,\text{g/cm}^3$), ferromagnetic in standard phases, and prone to oxidation (rust) unless alloyed.

Non-Ferrous Metals

Metals containing less than $1\%$ iron by weight with a non-iron base, exhibiting high natural corrosion resistance via passive oxide film formation, and generally displaying paramagnetic or diamagnetic (non-magnetic) behavior.

Pig Iron

The raw product of the blast furnace containing $3.5\% - 4.5\%$ carbon along with $\text{Si}$, $\text{Mn}$, $\text{P}$, and $\text{S}$; it is extremely brittle, unworkable directly, and serves as the primary precursor for steel.

Cast Iron

An iron-carbon alloy containing greater than $2.14\%$ carbon (typically $2.5\% - 4.0\%\,\text{C}$) that offers outstanding castability, high compressive strength, and excellent damping capacity, but is brittle in tension.

Wrought Iron

An ultra-pure iron containing less than $0.08\%$ carbon with fibrous slag inclusions that is highly ductile, tough, easily welded, and highly resistant to atmospheric corrosion.

Stainless Steel

An iron-carbon alloy containing a minimum of $10.5\%$ chromium ($\text{Cr}$), which forms an imperceptible passive $\text{Cr}_2\text{O}_3$ surface layer that prevents rust.

Hall-Petch Relationship

The physical principle establishing that crystal grain refinement increases material yield strength, expressed mathematically as $\sigma_y = \sigma_0 + k_y \cdot d^{-1/2}$.

Body-Centered Cubic (BCC)

A metallic unit cell geometry with corner atoms plus 1 central atom inside a unit cube, featuring a coordination number of $8$, an atomic packing factor (APF) of $0.68$, and $44$ slip systems.

Face-Centered Cubic (FCC)

A crystal structure consisting of corner atoms plus 1 atom centered on each of 6 cube faces, featuring a coordination number of $12$, an APF of $0.74$, and $12$ close-packed slip systems ($\{111\}\langle 110\rangle$).

Hexagonal Close-Packed (HCP)

A crystal structure with hexagonal top and bottom planes and 3 intermediate atoms, featuring a coordination number of $12$, an APF of $0.74$, and $3$ main slip systems ($\{0001\}\langle 11\bar{2}0\rangle$), resulting in low ductility and anisotropic, brittle behavior.

Thermoplastic Polymers

Polymers composed of linear or branched backbones held by weak secondary forces that soften repeatedly upon heating, harden when cooled, and can be easily remelted, reshaped, and recycled.

Thermosetting Polymers

Polymers characterized by cross-linked 3D networks with permanent covalent bonds that degrade, char, and decompose upon heating rather than melting, preventing mechanical recycling.

Elastomeric Polymers

Polymers consisting of lightly cross-linked chains with coiled structures, characterized by low modulus, high dynamic elasticity, and extreme elongation capability up to $1\,000\%$.

Polytetrafluoroethylene (PTFE)

An addition polymer synthesized from tetrafluoroethylene ($\text{CF}_2=\text{CF}_2$) featuring strong $\text{C}-\text{F}$ bonds that impart chemical inertness, high temperature resistance ($260\,^\circ\text{C}$), and an ultra-low friction coefficient.

Graft Copolymer

A copolymer architecture comprising a homopolymer main chain grafted with distinct side-branches of another monomer, such as Acrylonitrile-Butadiene-Styrene ($\text{ABS}$).

Troposphere

The lowest atmospheric layer ($0 - 12\,\text{km}$) containing $75 - 80\%$ of atmospheric mass and nearly all water vapor, where temperature decreases with altitude down to $\sim -55\,^\circ\text{C}$.

Stratosphere

The atmospheric layer ($12 - 50\,\text{km}$) characterized by an increasing temperature gradient up to $\sim 0\,^\circ\text{C}$ at the stratopause, hosting the ozone layer ($\text{O}_3$ peak at $20 - 30\,\text{km}$) which filters solar UV radiation.

Mesosphere

The atmospheric layer extending from $50 - 85\,\text{km}$ where temperatures decrease with altitude to $-90\,^\circ\text{C}$ (the coldest layer) and where incoming meteors burn up due to high-velocity gas friction.

Thermosphere / Ionosphere

The atmospheric layer ($85 - 600\,\text{km}$) where temperatures exceed $1\,500\,^\circ\text{C}$ due to solar X-ray/UV absorption; it contains ionized plasma that reflects shortwave radio signals and hosts auroras and the ISS.

Chlorofluorocarbons (CFCs)

Stable tropospheric compounds that break down under stratospheric UV radiation to release catalytic chlorine radicals ($\text{Cl}^\bullet$), each capable of destroying over $100\,000$ ozone ($\text{O}_3$) molecules.

Particulate Matter (PM2.5)

Fine suspended solid or liquid aerosols with an aerodynamic diameter less than $2.5\,\mu\text{m}$ that bypass nasal cilia and penetrate deep into pulmonary alveoli.

Loam Soil

The optimal agricultural soil texture consisting of an evenly balanced mixture of approximately $40\%$ sand, $40\%$ silt, and $20\%$ clay, providing ideal drainage, aeration, and fertility.

E Horizon

The eluvial soil layer characterized by intensive leaching, appearing light-colored because silicate clay, iron, and aluminum oxides have been stripped away, leaving resistant quartz and silt.

B Horizon

The illuvial subsoil zone of accumulation that collects clays, iron oxides, aluminum, and carbonates leached down from overlying horizons.

Cation Exchange Capacity (CEC)

The total capacity of a soil to retain and exchange cations, driven by negative surface charges on clay minerals and humus that attract essential nutrients ($\text{Ca}^{2+}$, $\text{Mg}^{2+}$, $\text{K}^{+}$, $\text{Na}^{+}$, $\text{NH}_4^{+}$).

Corrosives

Substances causing visible destruction or irreversible damage to living tissue or metals, characterized by extreme chemical action with $\text{pH} < 2$ or $\text{pH} > 12.5$.

Pyrophoric Substances

Substances that spontaneously ignite in air without an ignition spark at or below $54.4\,^\circ\text{C}$ ($130\,^\circ\text{F}$), such as white phosphorus, triethylaluminum, and silane gas.

Republic Act 6969 (RA 6969)

The Philippine Toxic Substances and Hazardous and Nuclear Wastes Control Act, providing statutory standards for chemical waste categorization, storage, transport manifests, and disposal.