Chemistry Unit 1.1

Ancient Views on Matter
Matter is anything that has mass and volume. But before this concept was established, ancient Greek philosophers were the first to speculate the nature of matter by providing different assumptions on what it is made of. Though Greek philosophers have ideas on what comprises matter, they only speculated on the nature of materials around them as they were not able to conduct experiments that will validate their assumptions.
One thing that Greek philosophers have agreed upon is the idea that all materials are made up of one primal matter. However, they differ in terms of what this primal matter was. According to Thales of Miletus (625–547 BC), the basic composition of matter was water since this material is found almost everywhere. On the other hand, Anaximenes (585–525 BC) proposed that matter was made up of air since its existence is more fluid than water. However, Heraclitus (535–475 BC) opposed these ideas as he believed that matter was made up of fire, since this element is a good representation of a “changing world.”
Another Greek philosopher, Empedocles (430–387 BC), combined the ideas of previous philosophers about the nature of matter. According to Empedocles, aside from water, air, and fire, matter was made up of earth too. This started the notion that matter was made up of four primal elements—water, air, fire, and earth.

Aristotle (384–322 BC), a renowned and influential philosopher during his time, expounded the idea of Empedocles. He described each element as a balance between two qualities. This allows early Greeks to explain the transformation of primal matter. For instance, air, which is hot and wet, will be converted to fire when dried while maintaining heat.

Aside from the idea that matter was made up of four elements, Aristotle suggested that all space is filled up with matter, thus, implying that there are no empty spaces. Since matter is not void, this means that it is divisible and can be cut into pieces over and over again. This started the principle of continuity of matter, wherein matter can be broken down into pieces and as you do so, you will not be able to obtain its smallest parts. Since Aristotle was well respected during his time, his idea was accepted and held by many over a long time.
Prior to Aristotle’s assumptions about the nature of matter, Leucippus (500 BC) and his student Democritus (460–370 BC) thought that all materials are made up of tiny bits of matter which cannot be divided further. The tiny indivisible part that makes up a matter is known as atom, which came from the Greek word atomos which means indivisible.

Particulate Nature of Matter
The idea of Democritus paved the way in establishing that matter is made up of particles instead of a primal material. This also started the principle of discontinuity of matter, wherein matter cannot be further divided into smaller bits once the ultimate particle of matter (atom) is obtained.
There are four main ideas in the particulate nature of matter:

  1. Matter is composed of discrete particles.
  2. There is an empty space between particles of matter.
  3. The particles of matter are in constant motion.
  4. There are forces that act between the particles.
    Discrete Particles of Matter
    Matter is made up of distinct particles. These particles may be in the form of molecules atoms, or ions. Atoms are the building blocks of matter. These are tiny indestructible particles that usually possess unique characteristics that define a certain matter. An atom is neutral by nature, but when it becomes charged—either positively or negatively—it becomes an ion. An ion is a particle or group of particles that are charged. A negatively charged ion is called anion while a positively charged ion is called cation. On the other
    hand, molecules are particles that are made up of two or more atoms that are chemically combined.
    On a macroscopic level, it is easy to describe what makes up a certain material. For instance, a table is made up of wood which is attached to one another using iron nails and/or wood glue. The surface of the wood is covered by either paint or varnish. However, distinguishable particles that make up a wood are hard to visualize on a macroscopic level. This prompted the use of particulate drawings to represent matter. Particulate drawings are illustrations used to have a visual representation of particles that make up matter.

Empty Space between Particles
The particulate nature of matter debunks the idea of Aristotle that there are no empty spaces. The particles that make up matter have spaces in between them. These spaces may be little or huge, depending on the kind of matter.
Take for example the mixing of food coloring in water. When food coloring is dropped in water, it will slowly spread out as its particles fill in the spaces between water molecules. When the food coloring is evenly spread out in the water, it shows that all empty spaces between water molecules are completely filled out by its particles.

Motion of Particles
Another nature of particles that make up matter is they are in constant motion. The speed and direction of moving particles vary in each kind of matter. The spaces between particles also dictate the kind of movement that particles in matter can do. For instance, matter with compact particles will have vibratory motion compared to the fast and random movement of particles that are far apart from one another.

Fig. 1.1.6. Particles that are close to one another (left) move in vibratory motion while particles that are far apart (right) move fast and in random directions.
Temperature can affect the movement of particles in matter. With an increase in temperature, particles in matter gain kinetic energy. The higher the kinetic energy of the particles, the faster its movement. Thus, increasing the temperature of matter enables its particles to move swiftly as well. The diagram below shows an increase in the speed of moving particles as temperature increases.

Fig. 1.1.7. As the temperature increases, particles gain kinetic energy which results in their fast movement.
Forces between Particles
Particles in matter are held by forces. Intermolecular forces or forces that exist between particles may be attractive or repulsive. For instance, a water droplet is able to maintain its shape due to the attractive forces that exist between its particles. On the other hand, water droplets are seen sliding down outside the glass of a cold drink due to the repulsive force that exists between the water particles and glass particles.

Fig. 1.1.8. The formation of water droplets on the sides of a glass of cold drink shows the attractive and repulsive forces between particles of water.
Compact materials show a strong attractive force between its particles. This is the reason why this kind of material is able to keep its shape and volume. On the other hand, almost negligible force exists between particles of matter that are far apart from one another.

The Particulate Nature of the Three States of Matter
Understanding the basic principles of the particulate nature of matter can provide a better view of the microscopic level of solid, liquid, and gas. Fig. 1.8 shows the particulate drawings of solid, liquid, and gas. The arrangement of particles, its motion, and intermolecular forces dictate the kind of state in which matter exists.

Arrangement of Particles
Particles in a solid matter are closely packed and are arranged in an orderly manner. This close arrangement limits the spaces between the particles of solid. Liquid particles are also close to one another but its arrangement is not as orderly as solids. However, there are relatively bigger spaces between liquid particles than solids. On the other hand, particles in the gaseous matter are far apart from one another and are arranged randomly. The far distances between particles make a gaseous matter mostly empty space.
Intermolecular Forces
The limited space between particles of solids is a consequence of the strong attractive forces between its particles. Particles in a solid matter are closely packed due to the strong attractive forces that hold them together. This is the reason why solids are able to maintain its shape and volume and have low compressibility and fluidity. The attractive forces between liquid particles are also strong but not as strong as the intermolecular forces in solids. This particulate nature allows most liquids to flow with ease and follow the shape of its container. However, attractive forces between gaseous particles are very minimal and almost negligible. Particles in gaseous matter tend to neglect one another due to the huge distances between them. Gases are highly compressible due to the very minimal forces that exist between its particles.

Motion of Particles
Particles in all states of matter are in constant motion. However, the arrangement of particles in each state of matter also dictates its kind of movement. Solid particles exhibit vibratory motion but in a fixed position. The limited spaces between particles of solids also restrict its motion to back-and-forth movements in defined positions. The relatively bigger distances between liquid particles allow them to slide past one another. This is the reason why liquids tend to occupy the bottom part of a container. On the other hand, the huge spaces and very minimal attractive forces between particles of gases enable them to move swiftly and in random directions.
Energy of Particles
Since particles are in constant motion, they also possess kinetic energy. The rate of motion of particles in matter also tells the amount of kinetic energy they possess. In solid matter, the particles are confined in fixed positions as they vibrate. The slow vibratory motion of solid particles shows that low energy they possess. Liquid particles have moderate speed as they slide past one another. This also results in the moderate energy that liquid particles possess. Moreover, gas particles that are moving swiftly and randomly possess high kinetic energy.