Understanding Atomic Structure

• Atoms are fundamental matter building blocks comprised of protons, neutrons, and electrons

Nucleus

• The nucleus is the atom's dense central core
• It contains protons which are positively charged particles
• An element's atomic number is determined by the number of protons
• Each proton has a +1 charge
• Neutrons are neutrally charged particles found in the nucleus
• Neutrons add mass and stabilize the nucleus
• Isotopes are atoms of the same element with varying neutron numbers
• Most of the atom's mass is contained in the nucleus, which is small relative to the atom's size

Electrons

• Electrons are negatively charged particles with a -1 charge
• Electrons are much less massive than protons and neutrons
• Orbitals, or energy levels, are the regions where electrons move around the nucleus
• In a neutral atom, the electron count equals the proton count

Subatomic Particles

• Protons have a +1 charge and located in the nucleus, with a relative mass of 1
• Neutrons have no charge and reside in the nucleus, also with a relative mass of 1
• Electrons have a -1 charge and exist outside the nucleus, with a relative mass of about 1/1836

Crude Oil

• It is a complex hydrocarbon mixture with varied chain lengths and boiling points
• Direct crude oil use is impossible, separation into fractions like petrol, diesel and kerosene is essential

Fractional Distillation

• Crude is highly heated (350–400°C) in a furnace, partially vaporizing into a hot gas/liquid mix

Fractionating Column

• The vapor then enters the column, which has a temperature gradient
• It goes from hot at the bottom and cooler at the top
• The column contains trays for vapor condensation

Hydrocarbon Separation

• As vapor ascends, temperature drops, causing hydrocarbons to condense at different heights based on boiling points
• Heavy fractions (like bitumen) condense at the bottom, light fractions (like gasoline) at the top

Fraction Collection

• Each condensed fraction is collected on a tray, examples include refinery gasses at the top, petrol, kerosene, diesel, lubricating oils, fuel oil, and bitumen at the bottom
• It works because each hydrocarbon chain has a unique boiling point
• Fractional distillation uses boiling point differences to physically separate hydrocarbons

Fraction Quick Summary

• Refinery gases have boiling point < 40°C and are used for heating, cooking, and fuel
• Petrol (Gasoline) has a boiling point of ~40–100°C and is used for car fuel
• Kerosene has a boiling point of ~100–150°C and is used for jet fuel
• Diesel has a boiling point is ~150–300°C and is used for vehicle engines
• Diesel has a boiling point of ~300–400°C and is used for ship engines and power plants
• Bitumen has a boiling point of >400°C and is used for roads and roofing

Alkanes

• Alkanes contain only single bonds between carbon atoms and are saturated hydrocarbons, with the general formula CnH2n+2

Methane

• Methane's formula is CH₄, it has one carbon atom bonded to four hydrogen atoms\

Ethane

• Ethane's formula is C₂H₆, it has two carbon atoms single-bonded, with six hydrogen atoms

Propane

• Propane's formula is C₃H₈, it consists of three carbon atoms in a chain with eight hydrogen atoms

Butane

• Butane's formula is C₄H₁₀, which consists of four carbon atoms in a straight chain (or isobutane branch), with ten hydrogen atoms

Metal and Acid Reactions

• Metals generally react with acid to produce salt and hydrogen gas
• Metal + Acid → Salt + Hydrogen gas
• Magnesium + Hydrochloric acid → Magnesium chloride + Hydrogen

Reaction observations indicating the production of hydrogen gas

• Fizzing/bubbling occurs
• The metal dissolves
• The reaction produces heat
• Metals react differently, ranging from violent to none

Metal Reactivity Series

• Metals are arranged from most to least reactive in the reactivity series
• Potassium (K) is the most reactive
• Platinum (Pt) is the least reactive

Metal Notes

• Potassium, sodium, and calcium react violently
• Magnesium through iron react moderately
• Copper to platinum do not react with acids, as they don't displace hydrogen

Hydrogen Test

• Placing a lit splint near hydrogen produces a "pop" sound

Mixture Separation-Filtration

• Used to separate insoluble solids from liquids, such as sand and water
• The mixture is poured through filter paper in a funnel
• The solid remains on the paper (residue)
• The liquid passes through into a beaker (filtrate)

Evaporation

• It is used to separate a soluble solid from a solution, like salt from saltwater
• The solution is heated until the water evaporates, leaving salt crystals

Crystallization

• It is used to produce pure crystals of a soluble solid from a solution, such as copper sulfate crystals
• The solution is gently heated to concentrate it
• Crystals form as it cools slowly
• Filter and dry the crystals

Distillation

• It is used to separate a liquid from a solution, such as pure water from salty water
• The solution is heated
• A condenser cools and collects the evaporated liquid while the solid remains

Fractional Distillation

• This is used to separate a liquid mixture with different boiling points, such as ethanol and water or crude oil fractions
• The mixture is heated
• Each component boils and is collected as it condenses separately

Chromatography

• It is used to separate different dyes or pigments
• A solvent is added after a mixture drop on filter paper
• Different dyes move differently, creating colored spots

Mixture Separation Summary

• Filtration is used for insoluble solids plus liquids (sand and water)
• Evaporation is used for soluble solids plus liquids (salt from seawater)
• Crystallization is used for soluble solids plus liquid pure crystals (copper sulfate from solution)
• Distillation is used for separating a liquid from a solution (water from salty water)
• Fractional Distillation is used for separating a mixture of liquids (ethanol + water, and crude oil)
• Chromatography is used for separating soluble substances (like dyes, and ink colors)

Gas Test - Hydrogen (H₂)

• Test involves holding a lit splint at the test tube's mouth
• A squeaky pop sound signifies hydrogen
• Hydrogen is flammable and reacts with oxygen, igniting

Oxygen (O₂)

• Test involves inserting a glowing splint into the test tube
• The glowing splint's re-ignition confirms oxygen
• Oxygen supports combustion

Carbon Dioxide (CO₂)

• Bubble the gas through limewater solution of calcium hydroxide
• Limewater turning milky confirms carbon dioxide
• CO₂ reacts with calcium hydroxide to form calcium carbonate, a white precipitate

Chlorine (Cl₂)

• Hold a damp blue litmus paper near chlorine gas
• Litmus paper turns red, then bleaches white
• Chlorine gas is toxic, acidic, and has bleaching properties

Reactive Gas Summary

• Hydrogen is tested with a lit splint and has a positive result of a squeaky pop sound
• Oxygen is tested with a glowing splint and has a positive result of the splint relighting
• Carbon Dioxide is tested by bubbling through limewater and has a positive result of limewater turning milky/cloudy
• Chlorine is tested with damp blue litmus paper and as a positive result turns red and then bleaches white

Present vs. Past Atmosphere

• Earth's atmosphere was originally CO₂, water vapor, and nitrogen, with little oxygen
• Today's atmosphere is about 78% nitrogen, 21% oxygen, and 1% other gases
• Human activities are altering carbon dioxide and other greenhouse gases

Fossil Fuels

• Activities like driving cars, powering factories, and heating homes burn fossil fuels
• This releases carbon dioxide into the atmosphere
• Increased CO₂ levels contribute to the greenhouse effect, global warming and climate change

Deforestation

• Cutting down forests reduces the amount of trees, which absorb CO₂
• Less carbon dioxide is removed leading to a buildup in the atmosphere and enhances global warming

Agriculture

• Farming, especially rice paddies and cattle farming, releases methane which is a potent greenhouse gas
• Fertilizer use releases nitrous oxide, which contributes to the greenhouse effect
• This leads to more greenhouse gases which trap more heat, affecting weather and ecosystems

Industrial Processes

• Some manufacturing processes release CO₂
• Chemicals release CFC's which damage the ozone layer, which protects from UV rays
• leads to CO₂ causing warming and CFCs causing ozone depletion

Greenhouse Gasses

• CO2 comes from fossil fuels and deforestation contributing to global warming
• CH4 comes from cattle farming and rice fields and contributes to global warming more than CO2
• N2O comes from fertilizers and causes global warming
• CFCs came from old aerosols and fridges and cause ozone depletion

Results of Global Warming

• Rising global temperatures
• Changing weather patterns
• Melting ice caps and rising sea levels
• More extreme weather (storms, floods, droughts)

Periodic Table-Historical Perspective

• In 1869, Dmitri Mendeleev arranged elements by atomic weight, placing similar properties in columns and leaving gaps for undiscovered elements, predicting their properties
• When elements like gallium and germanium were discovered later, they matched Mendeleev's predictions

Modern Perspective

• In the early 1900s, Henry Moseley arranged elements better by atomic number
• Noble gases were added later
• The modern table is organized by groups and periods which are elements with similar properties and elements with the same electron shells
• Atomic number is the number of protons, the order of elements
• Groups are vertical, and have elements with similar chemical properties
• Periods are horizontal and show the number of electron shells
• Separated areas on the table divide metals, non-metals, and metalloids
• Blocks indicate show electron configuration patterns

Historic vs. Modern

• Historical was ordered by atomic weight while modern is ordered by atomic number
• Historical had gaps for unknown elements while modern has no gaps.
• Historical had some elements out of order while modern fits correctly
• Historical had no noble gases while modern does

Atomic Number

• The amount of protons in the nucleus is the atomic number
• The atomic number is above the element on the periodic table
• Sodium (Na) has an atomic number of 11. It has 11 protons and electrons

Atomic Mass

• The atomic mass is the average mass of the element's atoms
• The atomic mass is located below the element's symbol on the periodic table
• Sodium's atomic mass is approximately 22.99

Reactions

Combustion

• A substance reacts with oxygen to produce carbon dioxide and water
• Example: Methane + Oxygen → Carbon dioxide + Water

Synthesis

• Two or more reactants combine to form a single product
• Example: Sodium + Chlorine → Sodium chloride

Decomposition

• A single compound breaks down into two or more simpler substances
• Example: Calcium carbonate → Calcium oxide + Carbon dioxide

Displacement

• One element replaces another in a compound
• Example: Zinc + Hydrochloric acid → Zinc chloride + Hydrogen

Neutralization

• An acid reacts with a base to produce salt and water
• Example: Hydrochloric acid + Sodium hydroxide → Sodium chloride + Water

Reaction summary

• Combustion produces CO₂ and H₂O from hydrocarbons
• Synthesis is when Two elements or compounds combine to form a single compound
• Decomposition is when a single compound breaks down into multiple products
• Displacement is when an element replaces another, forming a new compound
• Neutralization is when an acid and a base produce a salt and water
• Iron reacting with oxygen produces iron oxide
• Ammonium chloride decomposing produces ammonia and hydrogen chloride