• The science of Matter

• Deals with the structure and composition of matter

• Deals with the changes that matter undergoes and the energy involved that accompany these change

• Utilization:

  • Agriculture: Fertilizers, pesticide

  • Cosmetics: Perfume, cosmetic

  • Computer Technology: Computer chips, hardware

  • Electronics: Semiconductor, insulator

  • Education: Papers, ink, pens

  • Sports: Equipment, energy drink

  • Military: Guns, gunpowder, vests

  • Medicine: Imaging, drugs, prosthesis

BRANCHES OF CHEMISTRY

1. Inorganic Chemistry - study of all elements and their compounds except the element carbon.

2. Organic Chemistry -  study of carbon compounds, specifically hydrocarbons and their derivatives.

3. Biochemistry - study of compounds present in living organisms and their interaction with one another.

4. Physical Chemistry - study of physical processes in chemical reactions.

5. Analytical Chemistry - study of what and how much substance is present in a particular sample of matter.

HISTORY OF CHEMISTRY

• Ancient Babylonians - Chemistry as an art of brewing wine and extracting metals from ores.

• Ancient Egyptians - Chemistry as an art of embalming, cosmetics and making paper from papyrus.

• Ancient Greeks and Romans

  • Chemistry as an art of making alloys

  • Chemistry as an art of philosophy

• Middle Ages - Chemistry as an art of alchemy ( philosopher’s stone)

  • To make elixirs for immortality and convert ordinary metal into gold

• 16TH Century - Chemistry as analytical science.

• Modern Chemistry:

  • Robert Boyle – “The Skeptical Chymist ”,

  • Boyle’s Law Amadeo Avogadro – Avogadro’s number

  • Joseph Priestly – discovered Oxygen

  • Henry Cavendish – discovered Hydrogen

  • Antoine van Lavoisier – Father of Modern Chemistry/ named Oxygen & Hydrogen, Law of Conservation of Mass

  • Joseph Louis Proust – Law of Definite Proportion

L3: The Nature of Matter

PARTICULATE NATURE OF MATTER

• Democritus - matter is made up of small/tiny, uncut & indivisible particles called atomos/atoms.

• Matter has mass and occupies space.

• Matter can be classified according to their structure and composition.

• Atoms are single neutral particles; Molecules are particles made of two or more atoms bonded together

STATES OF MATTER

• Inter-convertibility depends on pressure and temperature.

• Matter exists in three states:

• SOLID:

  • Macroscopic View - Definite shape and Definite volume/ rigid substance with a definite shape

  • Microscopic View - Particles are very much close to each other.

  • Molecules - are held close to each other by their attractions of charge.

  • They will bend and/or vibrate, but will stay in close proximity.

• LIQUID:

  • Macroscopic View - Indefinite shape, Definite volume./ takes the shape of its container

  • Microscopic View - Particles are slightly loose, has weak force of attraction.

  • Molecules - will flow or glide over one another, but stay toward the bottom of the container.

  • Motion is a bit more random than that of a solid.

• GAS:

  • Macroscopic View - Indefinite shape, Indefinite volume/ takes the shape and volume of its container

  • Microscopic View - Particles are very much far from each other.

  • Molecules - are in continual straightline motion

  • The kinetic energy of the molecule is greater than the attractive force between them, thus they are much farther apart and move freely of each other.

  • When the molecules collide with each other, or with the walls of a container, there is no loss of energy.

• PHASE CHANGES:

  • Sol > Gas = Sublimation

  • Gas > Sol = Deposition

  • Sol > Liq = Freezing

  • Liq > Sol = Melting

  • Gas > Liq = Condensation

  • Liq > Gas = Evaporation

Kinetic Molecular Theory

• Explains the f__orces between molecules and the energy that they possess__.

• 3 basic assumptions:

  • Matter is composed of small particles (molecules).

  • The measure of space that the molecules occupy (volume) is derived from the space inbetween the molecules and not the space the molecules contain themselves.

  • The molecules are in constant motion. This motion is different for the 3 states of matter:

    • Solid = low KE & strong attractive forces

    • Liquids = KE & attractive forces are higher than solids and lower than gases

    • Gases = High KE & weak attractive force

Laws Regarding Matter

1. The amount of matter and total mass remains the same.

2. All Physical and Chemical Changes involve some transfer of energy.

   1. Energy can be as heat or light (Can cause physical/chemical changes)

3. Law of Constant Composition (Law of Conservation of Mass) - All samples of a given compound have the same proportions of their constituent elements.

4. Law of Conservation of Energy - Energy is not created or destroyed, only changed.

5. Law of definite proportion – A given compound always contains exactly the same proportion of elements by mass.

6. Law of multiple proportions – When two elements form a series of compounds, the ratios of the masses of the second element that combine with 1 gram of the first element can always be reduced to small whole numbers.

Physical and Chemical Properties and Changes

1. Properties are used to identify and separate the substance

   1. Ex: Substance = metals / Properties = conduct electricity

2. Matter can be classified as a mixture or a pure substance.

3. Matter undergoes physical and chemical changes:

   1. A physical change involves a change in one or more physical properties but no change in composition.

      1. Ex: cutting, melting, boiling, freezing

   2. A chemical change transforms a substance into one or more new substances.

      1. Ex: electrolysis, precipitates, formation of light/heat

4. Matter has both physical and chemical properties:

• Physical properties are the characteristics of a substance that do not involve changing to another substance./ Properties that retain the identity of matter.

  • Intensive /Intrinsic Physical Properties – physical properties of matter that are constant regardless of the amount of matter present. ( boiling point, melting point, density, color, odor, texture)

  • Extensive /Extrinsic Physical Properties – physical properties that are not constant and change with the amount of matter present. As such, they are dependent on the amount ( shape, size, length, mass, volume)

• Chemical properties describe a substance’s ability to change to a different substance./ tend to change the identity of matter

• EG:

  • Flammability ~> ashes

  • Toxicity ~> corrosiveness

  • Reactivity ~> explosiveness

  • Heat of Combustion; ability to form bubbles when heated.

Mixtures

• a blend of two or more kinds of matter, each of which retains its own identity and properties.

  • Parts can be mixed together physically and usually can be separated.

  • Contains various amounts of different substances, so the composition needs to be specified. (% Mass = EX: 5 % NaCl and 95 % water)

• Homogeneous - Uniform in composition/ Exist in One phase (Saltwater, air, milk, alloys)

  • Aka Solutions

  • Combined particles are very small (less than 1nm)

  • Solute (dissolved) & Solvent (dissolving). (Two Types):

    • Dilute Solution - solute < solvent

    • Concentrated Solution - solute > solvent

• Heterogeneous - Not Uniform in appearance or throughout/ can be separated (pizza, concrete, salad)

  • Components of mixtures are distinguished from each other. (Two Types):

    • Colloids - particle size ranges from 1nm to 1um

    • Suspensions - particles are large enough that they are affected by gravity (greater than 1um)

PURE SUBSTANCE

• Composed of one kind of matter

• Homogeneous in appearance/ a__lways has the same composition__

• Pure substances are of two types:

  • Elements which cannot be broken down chemically into simpler substances

  • Compounds which can be chemically broken down into elements

ELEMENTS

• contain only one type of atom – elemental copper contains only copper atoms and elemental gold contains only gold atoms.

• Periodic Table of Elements (118 elements)

• Classified as:

  • Metals: Lustrous, Good Conductors of Heat & Electricity, Malleable (can be hammered) & Ductile (thin), High Densities, High Boiling and Melting point

  • Non-metals: Dull, Insulators, Brittlem Low Densities, Low Boiling and Melting point

  • Semi-metals (metalloids)

COMPOUNDS

• are substances that contain two or more different types of atoms./ chemically combined

  • Eg. water, carbon dioxide, carbon monoxide, hydrogen peroxide

• Classifications (Chemical Bound):

  • Ionic Compounds - aka Salts/ metals and non-metals (NaCl)

  • Covalent Compounds - aka Molecular Compounds/ Two or more Non-metals (CO2)

• Classifications (Acid/Base Properties):

  • Acids - Hydrogen ions, H+/ tastes Sour/ change blue litmus paper to red/ chemically active with metals/ very corrosive (HCl)

  • Base - Hydroxide ions, OH-/ tastes Bitter/ change red litmus paper to blue/ very corrosive (NaOH)

• Classifications (Presence of Carbon Element):

  • Organic Compounds - contains carbon/hydrocarbon atoms

  • Inorganic Compounds - contains all elements except carbon (H2O)

SEPARATION TECHNIQUES OF MIXTURES:

1. Filtration - to filter a solid from a liquid/used for colloids & suspensions

   1. uses filtering device-filter paper

2. Decantation - used when the mixture consists of substances of different densities. /used for suspensions only

   1. The less dense substance is carefully poured off of the more dense one.

3. Centrifugation - used when the substances have very similar densities, or when one of the substances consists of very fine particles suspended in a liquid.

4. Electrolysis – electric current to separate water into hydrogen gas and oxygen gas

5. Chromatography - this technique separates substances (dyes and pigments) on the basis of differences in solubility in a solvent.

   1. Paper Chromatography = A solvent travels through paper by capillary action and carries the pigments with it.

6. Distillation - to remove dissolved substances from a liquid or to separate a mixture of liquids that have different boiling points.

WAYS OF SEPARATING MIXTURES:

• Mechanical methods –used for suspensions, use mechanical devices such as tongs, magnets,etc.

• Extraction –used for solution/colloid,uses extracting agent.