FORM ONE PHYSICS TOPIC 6: STRUCTURE AND PROPERTIES OF MATTER

TOPIC 6: STRUCTURE AND PROPERTIES OF MATTER 

Structure of Matter

State of matter is defined in terms of the phase transitions which indicate the change in structure and properties. Solids, liquids and gases all are made up of microscopic particles. The behavior of all these particles also varies in three phases.

The Concept of Matter

Explain the concept of matter

Matter is anything, such as a solid, liquid or gas, that has weight (mass) and occupies space. For anything to occupy space, it must have volume.

The Particular Nature of Matter

Justify the particulate nature of matter

Matter is made up of tiny particles. The particles are atom or molecules, examples of substances, which are made up of atoms, are: gold, copper, Argon and silver; and those made up of molecules includes oxygen, water and ammonia.

  • In solid, storm’s attractive forces hold molecules together so that they are not free to move but they can only vibrate about their mean positions.
  • In liquids there are weak forces of attraction between molecules therefore the molecules are free to move randomly. The distances between molecules in liquids are therefore are larger than in solids.

In case of gases the molecules experience very weak forces of attraction and hence they are free to move randomly filling the whole space of the containing vessel. The distances between molecules in gases are comparatively greater than those in solids and liquids as shown in the figure above.

Demonstration to show the intermolecular space in solids, liquid and gases.

The Kinetic Theory of Matter

Explain the kinetic theory of matter

Generally, when solid particles are placed in the source of lead the particles tends to move from hot area to cold areas. These particles move because it gains energy that called it Kinetic energy.

Kinetic theory of matter sometimes attempts to explain how properties of gases like pressure, temperature and volume remain in constant motion.

There are three main parts of the Kinetic theory of matter. This includes:

  1. Matter is made up of tiny invisible part.
  2. Matter comes in different sizes.
  3. There is a point that the smallest particles of matter can be the fastest.

Therefore kinetic theory of matter states, “All matter is composed of small particles”Or “Particles of matter are in steady motion and that all impacts between the units of matter are completely elastic”

Three States of Matter

Classify three states of matter

There are three states of matter, namely:

  1. Solid state
  2. Liquid state
  3. Gaseous state

Solid state is the state of matter, which include solid materials, in which the intermolecular force between molecules are greatest and distance between molecules is small. Examples of solid state are wood, iron, etc.

Liquid sate is the one of the state of matter in which the intermolecular forces are low compared to solid state, there is greater distance between one molecule and another. See on figure 1.0 (b) examples water, soda, kerosene, and petroleum.

Gaseous state is the state of matter in which there is no intermolecular forces between molecules hence molecules are free to move from one place to another examples of gases are hydrogen, oxygen, carbon dioxide gas.

Difference between solid state, liquid state and gaseous state of matter

Solid state Liquid state Gaseous state.
It concerns with solid matter It concerns with liquids/ fluids matter It concerns with gases
Have high intermolecular Low intermolecular force No intermolecular force
No distance between molecules There is little distance between molecules Molecules are far from each other
Good examples are iron materials, woods etc. Good examples are water, soda, kerosene and petrol Good examples are oxygen and hydrogen

Rownian Movement

According to Robert Brown: Brownian movement refers to the irregular motion of tiny particles suspended in fluid (liquid organs). Consider the demonstrationbelow

Robert Brown, an English Botanist, powered some pollen grain in water and observed that particles floating in the water were darting about.

The irregular motion of tiny particles suspended in a fluid (fluid or gas) is called Brownian movement.

The tiny particles dart about because liquid molecules that are in state of motion bombard them.

Elasticity

The Concept of Elasticity

Explain the concept of elasticity

When a force is applied to a body the dimension of the body is usually altered. If an iron wire is stretched by small force applied to it longitudinally, the wire returns to its original shape and size when the force is removed.

Elasticity can be defined as the property of the iron wire by which it recovers its original shape and size on removal of the stretching force.

The Relationship between Tension and Extension of a Loaded Elastic Material

Justify the relationship between tension and extension of a loaded elastic material

Consider the graph below:

Point A is called the elastic limit. The straight region OA of the graph has a slope K given by the ratio.

K= Tension/Extension

The ratio is called the force constant or coefficient of stiffness of the wire and it is expressed in newton per metre (N/M)

The Application of Elasticity in Real Life

Identify the applications of elasticity in real life

In everyday life we often actually do the activities that are concerned with the application of physics. Here are some of the application of physics in everyday life especially in the application of Elasticity:

  • Spring mattress. When you sit or sleep on a spring mattress, futon style push your weight. Pressured by the compressed spring mattress. Due to the nature of its elasticity, stretch a spring mattress again. Spring will be stretched and compressed, and so on.
  • Spring that is used as shock absorbers on motorcycles. Springs used in the suspension systems of motor vehicles. The purpose of this is to dampen spring a surprise when a motorcycle driven through an uneven road surface.
  • Another simple example and that you may often come across is the catapult. When it was about to shoot birds with catapults for example, rubber slingshots first stretch (given the gravity). Due to the nature of its elasticity, long rubber slingshots will return to normal after a tensile force is removed.

Adhesion and Cohesion

The Concept of Adhesion and Cohesion

Explain the concept adhesion and cohesion

Matter is made up of molecules. That exerts force of attraction. This force of attraction may be either Cohesion or Adhesion.

  • Cohesion is the force of attraction between the molecules of the same substance, example water to water molecules.
  • Adhesion is the force of attraction between the molecule of different substances example water to glass molecules.

Water molecules can experience the force of cohesion among themselves, where water molecules and glass molecules will experience force of adhesion.

Definite shapes of a solid are due to strong cohesion force among its molecules.

Shapes and meniscus of a liquid

When we carried out activities involving determination of volume in a liquid ring and measuring cylinder. The description indicated that the surface of the liquid was carved, forming a meniscus, and that the volume must be read at the bottom or top of the meniscus, depending on the liquid used. For mercury, the top of the meniscus is read.

The formation of a meniscus in a liquid is due to forces of adhesion between the liquid and the walls of the container. The adhesion of the liquid such as water to the wall of a vessel causes an upward force on the liquid at the edge.

The opposite takes place in mercury, the meniscus of water curves upwards forming a concave shape. When a drop of each liquid, mercury and water are placed on a glass sheet, water spreads further unlike mercury, because of mercury’s high cohesion force among its particle.

Why water wets the glass?

Why methanol does not wet the glass?

Applications of Adhesion and Cohesion in Daily Life

Identify the applications of adhesion and cohesion in daily life

Application include the following

  1. To stick two different objects together. Here we use the adhesive effects of tape or glue.
  2. Adhesion can also be used to remove harmful materials such as bacteria from drinking water. Adhesive forces are the source attraction substance.
  3. Cohesion assists in transport of water in plants and animals by allowing one molecule to pull others along with it.
  4. The bodies of plants and animals also use the cohesion of tissue to repair damage.
  5. Ink sticks on paper because of adhesive force between the paper and ink.

Surface Tension

The Concept of Surface Tension

Explain the concept of surface tension

While you may not be able to walk on water, water stride does. This is due to the property of liquid, which is known as surface tension.

Surface tension is the ability of the molecules on the surface of a liquid to attract and stick to each other allowing them to resist an external force. Surface tension enables insects such as water strides and mosquitoes to walk on water. It allows small objects even metallic ones such as needles and razor blades to float on the surface of water.

Surface tension is a resultant attractive force between molecules in a liquid. The molecules below the surface liquid have forces of attraction between neighbouring particles. However molecules at the surface have no neighbouring molecules above them. This makes them have stronger attractive force than their nearest neighbours on the surface.

However, when some detergent is added to water, the same objects sink to the bottom of the trough. This means that the detergent interfered with the surface of the liquid so decreasing the tension of the water surface.

Detergents are example of surfactants. A surfactant is a substance that reduces the surface tension of a liquid.

Note: the term surfactant is an aerogun for surface-active agent.

Surface tension is affected by the following

  • Nature of the liquid
  • Contamination/impurities
  • Temperature

Application at surface tension:

  1. In extraction of impurities dating laboratory process.
  2. Surfactants are also used to make emulsion of liquid like oil and water.
  3. In cleaning action of soap.

Applications of Surface Tension in Daily Life

Identify the applications of surface tension in daily life

Application at surface tension

  1. In extraction of impurities dating laboratory process
  2. Surfactants are also used to make emulsion of liquid like oil and water.
  3. In cleaning action of soap

Capillarity

The Concept of Capillarity

Explain the concept of capillarity

This is the tendency of a liquid to rise in narrow tubes or to be drawn into small openings such as those between the fibres of a towel. Capillarity can pull a column of liquid upward until the weight of liquid becomes greater than the surface tension.

In a tube, capillarity depends on the tube’s diameter but weight of water column depends on other factors besides it.

The smaller the radius of the tube the higher the liquid will rise in it. This implies that capillarity height is immensely proportional to the diameter of the tube.

By definition

Capillarity is defined as the tendency of liquid to rise in narrow tubes or to be drawn into small openings such as those between the fibres of a towel.

Capillarity action is the ability of a liquid to raise or fall in a narrow tube.

Note:

  1. Capillarity depends on the type of liquid. For example if you dip capillarity tube in water the water rises in the tube and above the level of the water in the vessel.
  2. If the tube is dipped in mercury, the liquid does not rise in the tube. It suffers capillarity depression.

Applications of Capillarity in Daily Life

Identify the applications of capillarity in daily life

The application includes:

  1. Capillarity is essential to plants and animals.
  2. In plants, it facilitates the transport of water and nutrients from the roots to the leaves where photosynthesis produces the plants food. In animals it assists in the circulation of blood.
  3. Capillarity promotes the movement of ground water.
  4. It is the principles on which paper and fabric towels work to absorb water.
  5. Cotton clothing in hot climates uses capillarity action to draw perspiration away from the body.
  6. In an oil or kerosene lamp capillarity draws the fuel up into the wicker where it can be burnt.
  7. A writing Rubin splits in the middle so that a fine capillary is formed.

Osmosis

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