2024 4NA Science Chemistry Lecture Notes

Comprehensive vocabulary flashcards covering Earth's atmosphere, chemical pollutants, organic chemistry, the periodic table, and experimental techniques based on the lecture notes.

Global warming

The increase in the average temperature of the Earth's surface due to increasing amounts of greenhouse gases in the atmosphere.

Carbon dioxide ($CO_2$)

A greenhouse gas produced by the combustion of fossil fuels and deforestation that traps heat and contributes to climate change.

Methane ($CH_4$)

A greenhouse gas produced as waste gas from cattle and through leakage from methane reservoirs.

Carbon Cycle

A natural system that regulates the amount of $CO_2$ in the atmosphere through processes like photosynthesis, respiration, and decomposition.

Photosynthesis

The process where plants take in $CO_2$ and $H_2O$ in the presence of sunlight to produce glucose and oxygen: $6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$.

Composition of Clean Air

A mixture consisting of approximately $78\%$ nitrogen, $21\%$ oxygen, $1\%$ noble gases (mainly argon), and $0.03\%$ carbon dioxide.

Oxygen ($O_2$)

A gas in the air needed for burning (combustion) and which causes the rusting of iron.

Carbon monoxide ($CO$)

A toxic air pollutant from incomplete combustion that combines with haemoglobin in the blood, preventing the transport of oxygen.

Sulfur dioxide ($SO_2$)

An acidic oxide produced from volcanic eruptions and burning fossil fuels like coal, causes breathing problems and acid rain.

Nitrogen oxides ($NO$ and $NO_2$)

Acidic oxides formed during lightning activity and in vehicle engines that lead to lung damage and acid rain.

Acid rain

Formed when $SO_2$ and $NO_2$ react with air and water in clouds to produce sulfuric acid ($H_2SO_4$) and nitric acid ($HNO_3$).

Polymers

Large molecules built up from many small units known as monomers.

Addition polymerisation

The process where unsaturated monomers (alkenes) join together without losing any atoms to form polymers like poly(ethene).

Non-biodegradable

Materials, such as many plastics, that take a very long time to break down, resulting in litter accumulation.

Homologous series

A family of organic compounds with similar chemical properties and the same general formula, where each member differs by a $-CH_2-$ group.

Alkanes

A homologous series of saturated hydrocarbons containing only single carbon-carbon bonds with the general formula $C_nH_{2n+2}$.

Alkenes

A homologous series of unsaturated hydrocarbons containing at least one carbon-carbon double bond ($C=C$) with the general formula $C_nH_{2n}$.

Aqueous bromine test

A chemical test where alkenes decolourise reddish-brown aqueous bromine, while alkanes do not.

Cracking

The process of breaking down large alkane molecules into small molecules using a solid catalyst ($Al_2O_3$ and $SiO_2$) at approximately $600\,^{\circ}C$.

Biofuels

Renewable energy sources, such as bioethanol obtained from the fermentation of sugar in sugarcane.

Group 1 elements (Alkali metals)

A group of soft metals with low density and low melting points that become more reactive and softer moving down the group.

Group 17 elements (Halogens)

Diatomic non-metals whose melting points and color intensity increase moving down the group while reactivity decreases.

Amphoteric oxides

Oxides such as $ZnO$, $Al_2O_3$, and $PbO$ that can react with both acids and alkalis.

Fractional distillation

A technique used to separate crude oil into useful fractions (like petrol, naphtha, and kerosene) based on their different boiling points.

Hydrocarbons

Organic compounds composed of only hydrogen and carbon atoms.

Alloy

A mixture of a metal with other elements, which is stronger and harder than pure metal due to the disruption of the orderly arrangement of atoms.

Acid

A substance that ionises in water to produce hydrogen ions ($H^+$).

Alkali

A metal hydroxide soluble in water that ionises to produce hydroxide ions ($OH^-$).

Kinetic Particle Theory

The theory stating all matter is made of small discrete particles in constant random motion.

Sublimation

The physical change where a solid transforms directly into a gas, such as dry ice, iodine crystals, or ammonium chloride.

Chromatography

A separation technique used to distinguish and separate mixtures of substances like dyes based on their solubility in a solvent.