Chemistry Study Notes

• Study notes for Chemistry topics: Atomic Structure, Forming Ions, Bonding Basics, The Periodic Table, Crude Oil and Fuel, Energy Changes, Chemistry of the Atmosphere, Extracting Metals, Alternative Extraction Methods, Materials, Calculations, Reactivity of Metals, Acids, Rates of Reaction, Organic Chemistry, Rate and Extent of Chemical Change, Chemical Changes, Quantitative Chemistry.

Atomic Structure

• Atoms are composed of protons, neutrons, and electrons.
• Protons have a positive charge, electrons have a negative charge, and neutrons are neutral.
• The number of protons determines the element.
• The number of protons equals the number of electrons in a neutral atom.
• The mass number is the total number of protons and neutrons in an atom.
• Isotopes are atoms of the same element with different numbers of neutrons.

Forming Ions

• Ions are formed when atoms gain or lose electrons.
• Positive ions (cations) are formed when atoms lose electrons.
• Negative ions (anions) are formed when atoms gain electrons.
• Ionic compounds are formed through the electrostatic attraction between oppositely charged ions.

Bonding Basics

• Ionic bonds involve the transfer of electrons between atoms.
• Covalent bonds involve the sharing of electrons between atoms.
• Metallic bonds involve the delocalization of electrons within a metal lattice.
• The type of bonding affects the physical properties of a substance, such as melting point and conductivity.
• Dot and cross diagrams are used to represent bonding in molecules.

The Periodic Table

• Elements are arranged in order of increasing atomic number.
• Elements in the same group have similar chemical properties due to having the same number of outer shell electrons.
• Metals are on the left side and non-metals are on the right side.
• Group 1 are the alkali metals.
• Group 7 are the halogens.
• Group 0 are the noble gases.
• Transition metals are located in the central block of the periodic table.

Crude Oil and Fuel

• Crude oil is a complex mixture of hydrocarbons.
• Fractional distillation separates crude oil into fractions based on boiling point.
• Shorter hydrocarbon chains have lower boiling points and are more flammable.
• Cracking breaks down larger hydrocarbons into smaller, more useful ones.
• Combustion of fuels releases energy.
• Burning hydrocarbon fuels produces carbon dioxide and water.

Energy Changes

• Exothermic reactions release energy, resulting in a temperature increase.
• Endothermic reactions absorb energy, resulting in a temperature decrease.
• Activation energy is the minimum energy required for a reaction to occur.
• Catalysts lower the activation energy, speeding up the reaction.
• Energy change is calculated using bond energies: energy change = sum of bonds broken - sum of bonds formed.

Chemistry of the Atmosphere

• The early atmosphere was mainly carbon dioxide.
• Over time, carbon dioxide levels decreased due to the formation of sedimentary rocks and the evolution of photosynthetic organisms.
• The current atmosphere is composed mainly of nitrogen and oxygen.
• Greenhouse gases trap heat and contribute to global warming.
• Air pollution is caused by the release of harmful substances into the atmosphere.

Extracting Metals

• Metals are extracted from their ores through various methods.
• Electrolysis is used to extract reactive metals.
• Reduction with carbon is used to extract less reactive metals.
• Bioleaching and phytomining are alternative methods of extraction.

Alternative Extraction Methods

• Bioleaching uses bacteria to extract metals from low-grade ores.
• Phytomining uses plants to absorb metals from the soil.

Materials

• Polymers are large molecules made up of repeating units (monomers).
• Thermoplastics can be repeatedly softened and reshaped.
• Thermosetting polymers are rigid and do not soften upon heating.
• Composites are materials made from two or more different materials.
• Ceramics are non-metallic solids with high melting points.
• The properties of materials depend on their structure and bonding.
• Nanomaterials have unique properties due to their small size.

Calculations

• Relative atomic mass (Ar) is the average mass of an atom of an element compared to 1/12th the mass of a carbon-12 atom.
• Relative formula mass (Mr) is the sum of the relative atomic masses of all the atoms in a formula.
• Moles = mass / Mr .
• Concentration = moles / volume.
• Percentage yield = (actual yield / theoretical yield) x 100.
• Atom economy = (Mr of desired product / Mr of all reactants) x 100.

Reactivity of Metals

• Metals react differently depending on their position in the reactivity series.
• Metals higher in the series displace metals lower in the series from their compounds.
• Oxidation is the loss of electrons.
• Reduction is the gain of electrons.
• Redox reactions involve both oxidation and reduction.
• Ionic equations show only the species that participate in a reaction.
• Half equations show the oxidation or reduction process separately.

Acids

• Acids have a pH less than 7.
• Alkalis have a pH greater than 7.
• Neutral substances have a pH of 7.
• Acids donate protons (H+ ions).
• Bases accept protons.
• Neutralization is the reaction between an acid and a base.
• Strong acids completely ionize in water.
• Weak acids partially ionize in water.
• Titration is used to determine the concentration of an acid or base.

Rates of Reaction

• The rate of a reaction is the change in concentration of reactants or products per unit time.
• Factors affecting reaction rate include temperature, concentration, surface area, and catalysts.
• Increasing the temperature increases the kinetic energy of particles, leading to more frequent and energetic collisions.
• Increasing the concentration increases the frequency of collisions.
• Increasing the surface area increases the number of particles available for reaction.
• Catalysts speed up reactions by providing an alternative reaction pathway with lower activation energy.

Organic Chemistry

• Organic chemistry is the study of carbon-containing compounds.
• Alkanes are saturated hydrocarbons with single bonds only.
• Alkenes are unsaturated hydrocarbons with at least one double bond.
• Alcohols contain the -OH functional group.
• Carboxylic acids contain the -COOH functional group.
• Polymers are large molecules made up of repeating units (monomers).

Rate and Extent of Chemical Change

Chemical Changes

Quantitative Chemistry