English Version HSC Chemistry Note

English Version HSC Chemistry Note. Chemistry is the scientific discipline involved with compounds composed of atoms, i.e. elements, and molecules, i.e. combinations of atoms: their composition, structure, properties, behavior and the changes they undergo during a reaction with other compounds. Chemistry addresses topics such as how atoms and molecules interact via chemical bonds to form new chemical compounds. There are four types of chemical bonds: covalent bonds, in which compounds share one or more electron(s); ionic bonds, in which a compound donates one or more electrons to another compound to produce ions: cations and anions; hydrogen bonds; and Van der Waals force bonds. See glossary of chemistry.

English Version HSC Chemistry Note

English Version HSC Chemistry 1st Paper Note

English Version HSC Chemistry 2nd Paper Note

In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both basic and applied scientific disciplines at a fundamental level. Examples include plant chemistry (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the properties of the soil on the moon (astrophysics), how medications work (pharmacology), and how to collect DNA evidence at a crime scene (forensics).

Chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. Some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. Understanding chemical changes is a major part of the science of chemistry.

Many laboratories contain significant risks, and the prevention of laboratory accidents requires great care and constant vigilance. Examples of risk factors include high voltages, high and low pressures and temperatures, corrosive and toxic chemicals, and biohazards including infective organisms and their toxins. Measures to protect against laboratory accidents include safety training and enforcement of laboratory safety policies, safety review of experimental designs, the use of personal protective equipment, and the use of the buddy system for, particularly risky operations.

Chemical marine pollution can cause many disturbances which, in the shorter or longer term, can have a negative impact on the economy. These effects may be related to living organisms, ecosystems as well as humans and their activities. The methods used to assess economic impact distinguish all that is of commercial value from all that is not. Resources of Resources can easily be calculated as they cover all that can be invoiced. An example of this is a professional fishing ban due to the intoxication of fish flesh or due to a decrease in tourism in the incident area. Resources of non-commercial value are difficult to calculate as they cover all that cannot be invoiced.

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