Introduction to chemistry

We all want to make stuff. But, fundamentally we are just converting matter into more useful forms. That is what chemistry is all about understanding matter aka stuff so we can alter it to make our lives better. This introduction to chemistry is the first in our free interactive textbook to take you up to and beyond first year university level chemistry.

Perhaps you have have changed matter before – altering its shape without altering the chemicals it is made of. This is known as a physical change and has been around since the Stone Age, where people made tools from stone and toys from wood.

With the discovery of fire people learned to change the chemical composition of stuff. Think chemical changes such as bread baking or boiling eggs. The Greek philosophers’ tried to understand chemistry with the theory of the four elements: earth, air, fire, and water. Followed my the medieval alchemy which tried to turn metals into gold and create a universal miracle medicine. Nowadays, we have modern chemistry seeking to understand the chemical universe through experimentation and observation. It has numerous applications in biology, medicine, materials science, environmental science, and many other fields. Chemistry is referred to as the central science as it is interrelated with many STEM disciplines and has a significant impact on our daily lives.

The Three Domains of Chemistry help us to study matter and energy at the macroscopic, microscopic, and symbolic level. Each domain provides a unique way of understanding and explaining chemical behaviour and using all three empowers us to use chemistry to invent and innovate.

The macroscopic domain, which comes from the Greek word “large,” involves the realm of everyday things that can be directly seen or felt by humans, such as food and wind. In this domain, physical and chemical properties such as density, solubility, and flammability are observed and measured.

The microscopic domain, which comes from the Greek word “small,” refers to the realm of objects too small to be seen by the naked eye, such as ions, electrons, and chemical bonds. Microscopic entities can’t usually be viewed with microscopes, instead they can only be imagined in the mind.

The symbolic domain involves the use of specialized language and symbols to represent both the macroscopic and microscopic domains. Chemical symbols, formulas, equations, graphs, drawings, and calculations are all part of this domain. These symbols play a crucial role in interpreting macroscopic behavior in terms of the microscopic components, but it can be challenging for students to understand that the same symbol can represent different things in each domain.

Introduction to chemistry and the three domains

Figure 1. Seeing the three domains of chemistry (a) is the macro domain, (b) is the micro domain, (c) is the symbolic domain

One useful approach to comprehend the three domains of chemistry is through the study of water, a common and crucial substance. Its physical state of being a liquid at normal temperatures, turning into a solid when frozen, and transforming into a gas when boiling (as shown in (a) the above Figure) are macroscopic observations that can be directly perceived. However, some of water’s properties are microscopic and cannot be seen by the naked eye, such as its composition of two hydrogen atoms and one oxygen atom, and the molecular interactions that cause freezing and boiling (seen in (b)). The formula H2O, which can describe water at both the macroscopic and microscopic level, represents the symbolic domain (s). Additionally, the abbreviations (g) for gas, (s) for solid, and (l) for liquid are also symbols.

Chemistry can be easy when we understand we are studying matter and energy at the macroscopic, microscopic and symbolic levels.

Introduction to chemistry questions.

Question 1. [1 mark each]

Predict whether these are chemical or physical changes:

a) Chopping onions with a knife

b) Burning toast

c) Adding salt to water

d) Boiling an egg


Question 2. [3 marks]

Explain the three domain of chemistry that we can use to understand a piece of chocolate


Question 3. [divergent thinking challenge question]

Draw the three domain of chemistry that we can use to understand a fire.

Answers.

Question 1.

a) Chopping onions with a knife – physical change

b) Burning toast – chemical change

c) Adding salt to water – physical change

d) Boiling an egg – chemical change

Question 2.

Macroscopic domain: The brown mass we can see

Microscopic domain merges with the symbolic:

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