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@@ -34,7 +34,7 @@
 
 \subsection{Alkali metals}
 
-\textbf{Elements:}
+\subsubsection{Elements}
 
 \begin{table}[H]
 \centering
@@ -52,7 +52,7 @@ Atomic No. & Symbol & English Name & Latin Name & Rel. Atomic Mass \\
 \end{tabular}
 \end{table}
 
-\textbf{Elementary Substances:}
+\subsubsection{Elementary Substances}
 
 \begin{table}[H]
 \centering
@@ -71,15 +71,15 @@ Fr & 27 & 677 & --- & Radioactive, no use \\
 \end{tabular}
 \end{table}
 
-\textbf{Preparation Methods:}
+\subsubsection{Preparation Methods}
 
-\textit{Sodium (Na):} Electrolysis of molten NaCl: \ce{2NaCl ->[electrolysis] 2Na + Cl2 ^}
+\textbf{Sodium (Na):} Electrolysis of molten NaCl: \ce{2NaCl ->[electrolysis] 2Na + Cl2 ^}
 
-\textit{Potassium (K):} Reduction of KCl with Na at high temperature: \ce{KCl + Na ->[high T] K ^ + NaCl}
+\textbf{Potassium (K):} Reduction of KCl with Na at high temperature: \ce{KCl + Na ->[high T] K ^ + NaCl}
 
 \subsection{Alkaline earth metals}
 
-\textbf{Elements:}
+\subsubsection{Elements}
 
 \begin{table}[H]
 \centering
@@ -97,7 +97,7 @@ Atomic No. & Symbol & English Name & Latin Name & Rel. Atomic Mass \\
 \end{tabular}
 \end{table}
 
-\textbf{Elementary Substances:}
+\subsubsection{Elementary Substances}
 
 \begin{table}[H]
 \centering
@@ -116,17 +116,17 @@ Ra & 700 & 1737 & BCC & Radioactive, obsolete \\
 \end{tabular}
 \end{table}
 
-\textbf{Preparation Methods:}
+\subsubsection{Preparation Methods}
 
-\textit{Magnesium (Mg):} Electrolysis of molten MgCl$_2$: \ce{MgCl2 ->[electrolysis] Mg + Cl2 ^}
+\textbf{Magnesium (Mg):} Electrolysis of molten MgCl$_2$: \ce{MgCl2 ->[electrolysis] Mg + Cl2 ^}
 
 Alternatively, reduction of MgO with coke: \ce{MgO + C ->[high T] Mg ^ + CO ^}
 
-\textit{Calcium (Ca):} Electrolysis of molten CaCl$_2$ or reduction of CaO with Al
+\textbf{Calcium (Ca):} Electrolysis of molten CaCl$_2$ or reduction of CaO with Al
 
 \subsection{Transition metals}
 
-\textbf{Elements (First Row):}
+\subsubsection{Elements (First Row)}
 
 \begin{table}[H]
 \centering
@@ -149,7 +149,7 @@ Atomic No. & Symbol & English Name & Latin Name & Rel. Atomic Mass \\
 \end{tabular}
 \end{table}
 
-\textbf{Important Elements (Other Rows):}
+\subsubsection{Important Elements (Other Rows)}
 
 \begin{table}[H]
 \centering
@@ -167,7 +167,7 @@ Atomic No. & Symbol & English Name & Latin Name & Rel. Atomic Mass \\
 \end{tabular}
 \end{table}
 
-\textbf{Elementary Substances:}
+\subsubsection{Elementary Substances}
 
 \begin{longtable}{p{1.3cm}p{1.6cm}p{1.6cm}p{2.2cm}p{4.5cm}}
 \toprule
@@ -196,21 +196,21 @@ Hg & -38.8 & 356.7 & Rhombohedral & Thermometers, lamps \\
 \bottomrule
 \end{longtable}
 
-\textbf{Preparation Methods:}
+\subsubsection{Preparation Methods}
 
-\textit{Iron (Fe):} Reduction in blast furnace: \ce{Fe2O3 + 3CO ->[high T] 2Fe + 3CO2}
+\textbf{Iron (Fe):} Reduction in blast furnace: \ce{Fe2O3 + 3CO ->[high T] 2Fe + 3CO2}
 
-\textit{Copper (Cu):} Roasting sulfide ore then reduction: \ce{2Cu2S + 3O2 -> 2Cu2O + 2SO2}, then \ce{Cu2S + 2Cu2O -> 6Cu + SO2 ^}
+\textbf{Copper (Cu):} Roasting sulfide ore then reduction: \ce{2Cu2S + 3O2 -> 2Cu2O + 2SO2}, then \ce{Cu2S + 2Cu2O -> 6Cu + SO2 ^}
 
 Alternatively, leaching and electrowinning from oxide ores.
 
-\textit{Zinc (Zn):} Roasting then reduction with carbon: \ce{2ZnS + 3O2 -> 2ZnO + 2SO2}, then \ce{ZnO + C -> Zn + CO}
+\textbf{Zinc (Zn):} Roasting then reduction with carbon: \ce{2ZnS + 3O2 -> 2ZnO + 2SO2}, then \ce{ZnO + C -> Zn + CO}
 
-\textit{Chromium (Cr):} Reduction of Cr$_2$O$_3$ with aluminum (thermite process): \ce{Cr2O3 + 2Al -> 2Cr + Al2O3}
+\textbf{Chromium (Cr):} Reduction of Cr$_2$O$_3$ with aluminum (thermite process): \ce{Cr2O3 + 2Al -> 2Cr + Al2O3}
 
 \subsection{Post-transition metals}
 
-\textbf{Elements:}
+\subsubsection{Elements}
 
 \begin{table}[H]
 \centering
@@ -229,7 +229,7 @@ Atomic No. & Symbol & English Name & Latin Name & Rel. Atomic Mass \\
 \end{tabular}
 \end{table}
 
-\textbf{Elementary Substances:}
+\subsubsection{Elementary Substances}
 
 \begin{table}[H]
 \centering
@@ -249,19 +249,19 @@ Bi & 271.4 & 1564 & Rhombohedral & Alloys, cosmetics \\
 \end{tabular}
 \end{table}
 
-\textbf{Preparation Methods:}
+\subsubsection{Preparation Methods}
 
-\textit{Aluminum (Al):} Hall-H\'eroult process (electrolysis of Al$_2$O$_3$ dissolved in molten cryolite): 
+\textbf{Aluminum (Al):} Hall-H\'eroult process (electrolysis of Al$_2$O$_3$ dissolved in molten cryolite): 
 
 \ce{2Al2O3 ->[electrolysis] 4Al + 3O2 ^}
 
-\textit{Lead (Pb):} Roasting galena (PbS) then reduction: \ce{2PbS + 3O2 -> 2PbO + 2SO2}, then \ce{PbO + C -> Pb + CO}
+\textbf{Lead (Pb):} Roasting galena (PbS) then reduction: \ce{2PbS + 3O2 -> 2PbO + 2SO2}, then \ce{PbO + C -> Pb + CO}
 
-\textit{Tin (Sn):} Reduction of cassiterite (SnO$_2$) with carbon: \ce{SnO2 + 2C -> Sn + 2CO ^}
+\textbf{Tin (Sn):} Reduction of cassiterite (SnO$_2$) with carbon: \ce{SnO2 + 2C -> Sn + 2CO ^}
 
 \subsection{Metalloids}
 
-\textbf{Elements:}
+\subsubsection{Elements}
 
 \begin{table}[H]
 \centering
@@ -280,7 +280,7 @@ Atomic No. & Symbol & English Name & Latin Name & Rel. Atomic Mass \\
 \end{tabular}
 \end{table}
 
-\textbf{Elementary Substances:}
+\subsubsection{Elementary Substances}
 
 \begin{table}[H]
 \centering
@@ -300,15 +300,15 @@ Po & 254 & 962 & Cubic & Radioactive, no common use \\
 \end{tabular}
 \end{table}
 
-\textbf{Preparation Methods:}
+\subsubsection{Preparation Methods}
 
-\textit{Silicon (Si):} Reduction of silica (SiO$_2$) with carbon in electric furnace: \ce{SiO2 + 2C ->[high T] Si + 2CO ^}
+\textbf{Silicon (Si):} Reduction of silica (SiO$_2$) with carbon in electric furnace: \ce{SiO2 + 2C ->[high T] Si + 2CO ^}
 
 For ultrapure silicon (semiconductors): Trichlorosilane reduction: \ce{SiHCl3 + H2 ->[high T] Si + 3HCl}
 
 \subsection{Halogen}
 
-\textbf{Elements:}
+\subsubsection{Elements}
 
 \begin{table}[H]
 \centering
@@ -325,7 +325,7 @@ Atomic No. & Symbol & English Name & Latin Name & Rel. Atomic Mass \\
 \end{tabular}
 \end{table}
 
-\textbf{Elementary Substances:}
+\subsubsection{Elementary Substances}
 
 \begin{table}[H]
 \centering
@@ -343,23 +343,23 @@ At$_2$ & 302 & 337 & Solid (radioactive) & No practical use \\
 \end{tabular}
 \end{table}
 
-\textbf{Preparation Methods:}
+\subsubsection{Preparation Methods}
 
-\textit{Chlorine (Cl$_2$):} Electrolysis of brine (chlor-alkali process): \ce{2NaCl + 2H2O ->[electrolysis] Cl2 ^ + H2 ^ + 2NaOH}
+\textbf{Chlorine (Cl$_2$):} Electrolysis of brine (chlor-alkali process): \ce{2NaCl + 2H2O ->[electrolysis] Cl2 ^ + H2 ^ + 2NaOH}
 
 Laboratory: Oxidation of HCl: \ce{MnO2 + 4HCl ->[heat] MnCl2 + Cl2 ^ + 2H2O}
 
-\textit{Bromine (Br$_2$):} Oxidation of bromide in seawater: \ce{2Br- + Cl2 -> Br2 + 2Cl-}
+\textbf{Bromine (Br$_2$):} Oxidation of bromide in seawater: \ce{2Br- + Cl2 -> Br2 + 2Cl-}
 
-\textit{Iodine (I$_2$):} Oxidation of iodide from brine or seaweed: \ce{2I- + Cl2 -> I2 + 2Cl-}
+\textbf{Iodine (I$_2$):} Oxidation of iodide from brine or seaweed: \ce{2I- + Cl2 -> I2 + 2Cl-}
 
 Or from Chile saltpeter: \ce{2NaIO3 + 5NaHSO3 -> I2 + 3NaHSO4 + 2Na2SO4 + H2O}
 
-\textit{Fluorine (F$_2$):} Electrolysis of KF in anhydrous HF: \ce{2HF ->[electrolysis] H2 + F2 ^}
+\textbf{Fluorine (F$_2$):} Electrolysis of KF in anhydrous HF: \ce{2HF ->[electrolysis] H2 + F2 ^}
 
 \subsection{Noble gases}
 
-\textbf{Elements:}
+\subsubsection{Elements}
 
 \begin{table}[H]
 \centering
@@ -377,7 +377,7 @@ Atomic No. & Symbol & English Name & Latin Name & Rel. Atomic Mass \\
 \end{tabular}
 \end{table}
 
-\textbf{Elementary Substances:}
+\subsubsection{Elementary Substances}
 
 \begin{table}[H]
 \centering
@@ -396,17 +396,17 @@ Rn & -71 & -61.7 & Colorless gas & Radioactive tracer \\
 \end{tabular}
 \end{table}
 
-\textbf{Preparation:}
+\subsubsection{Preparation}
 
 Noble gases are obtained by fractional distillation of liquid air (except He and Rn).
 
-\textit{Helium (He):} Extracted from natural gas wells.
+\textbf{Helium (He):} Extracted from natural gas wells.
 
-\textit{Radon (Rn):} Decay product of radium, collected from uranium/thorium ores.
+\textbf{Radon (Rn):} Decay product of radium, collected from uranium/thorium ores.
 
 \subsection{Other Nonmetals}
 
-\textbf{Elements:}
+\subsubsection{Elements}
 
 \begin{table}[H]
 \centering
@@ -425,7 +425,7 @@ Atomic No. & Symbol & English Name & Latin Name & Rel. Atomic Mass \\
 \end{tabular}
 \end{table}
 
-\textbf{Elementary Substances:}
+\subsubsection{Elementary Substances}
 
 \begin{longtable}{p{1.3cm}p{1.6cm}p{1.6cm}p{2.3cm}p{4.3cm}}
 \toprule
@@ -452,16 +452,16 @@ Se (gray) & 221 & 685 & Hexagonal & Photocells, glass \\
 \bottomrule
 \end{longtable}
 
-\textbf{Preparation Methods:}
+\subsubsection{Preparation Methods}
 
-\textit{Hydrogen (H$_2$):} 
+\textbf{Hydrogen (H$_2$):} 
 \begin{itemize}
 \item Steam reforming of methane: \ce{CH4 + H2O <=>[catalyst][high T] CO + 3H2}
 \item Electrolysis of water: \ce{2H2O ->[electrolysis] 2H2 ^ + O2 ^}
 \item Laboratory: Reaction of metals with acids: \ce{Zn + 2HCl -> ZnCl2 + H2 ^}
 \end{itemize}
 
-\textit{Oxygen (O$_2$):} 
+\textbf{Oxygen (O$_2$):} 
 \begin{itemize}
 \item Fractional distillation of liquid air
 \item Electrolysis of water: \ce{2H2O ->[electrolysis] 2H2 ^ + O2 ^}
@@ -469,17 +469,17 @@ Se (gray) & 221 & 685 & Hexagonal & Photocells, glass \\
 \item Or: \ce{2KClO3 ->[MnO2, heat] 2KCl + 3O2 ^}
 \end{itemize}
 
-\textit{Nitrogen (N$_2$):} Fractional distillation of liquid air
+\textbf{Nitrogen (N$_2$):} Fractional distillation of liquid air
 
-\textit{Chlorine (Cl$_2$):} See Halogen section
+\textbf{Chlorine (Cl$_2$):} See Halogen section
 
-\textit{Sulfur (S):} 
+\textbf{Sulfur (S):} 
 \begin{itemize}
 \item Frasch process: Melting underground sulfur with superheated water
 \item Recovered from petroleum refining and natural gas processing
 \end{itemize}
 
-\textit{Phosphorus (P):} Reduction of phosphate rock with coke and silica: 
+\textbf{Phosphorus (P):} Reduction of phosphate rock with coke and silica: 
 
 \ce{2Ca3(PO4)2 + 6SiO2 + 10C ->[high T] 6CaSiO3 + 10CO ^ + P4 ^}