TXSA 111 CHEMISTRY

SEMESTER 1—JANUARY 2013 BY: MR PS NKOSI

SYLLABUS BASIC CONCEPTS ABOUT MATTER. ATOMIC STRUCTURE AND PERIODIC TABLE. CHEMICAL BONDING AND INTERMOLECULAR FORCES. THE MOLE CONCEPT AND BALANCING CHEMICAL

EQUATIONS. SOLUTION. ACIDS AND BASES. OXIDATION AND REDUCTION. INTRODUCTION TO ORGANIC CHEMISTRY. INTRODUCTION TO INORGANIC CHEMISTRY. …….................................................................................................... PS Nkosi, Durban University of Technology, Department of Clothing and Textile Studies 2

BASIC CONCEPTS ABOUT MATTER CHEMISTRY is the study of matter and the changes it

undergoes. Structure Properties

MATTER is all substances of the universe, living and non-living.

It made up of molecules and atoms. It can be changed from one state to another by

Adding or removing heat Pressurizing

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Matter is usually classified into three classical states of matter, with plasma sometimes added as a fourth state for scientific purposes. From left to right: grains of refined sucrose (a solid), water (a liquid), depiction of particles in a gas, and a plasma globe (plasma).

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The properties of substance can be used in a number of ways: 1. To identify an unknown substance, e.g in chemistry

laboratories, crime labs and medical labs. 2. To distinguish between different substances, e.g.

gold and fake gold. 3. To characterize a newly discovered substance- the

substance is new if it has a unique set of properties. 4. Predicting the usefulness of a substance for specific

applications, e.g carbon monoxide is not used as an atmosphere in space capsules

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PHYSICAL PROPERTIES This are characteristics of matter that can be observed

or measured without altering the chemical composition and identity of the substance. E.g. State, colour, density, melting point, boiling point,

volume, temperature, mass.

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CHEMICAL PROPERTIES This are properties can be observed if a change in

chemical composition and identity of a substance occurs. E.g. Charcoal burns, iron rusts

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CLASSIFY EACH OF THE FOLLOWING AS CHEMICAL OR PHYSICAL a) A substance is very hard. b) A substance melts at 48 degrees. c) A substance is flammable. d) A substance is green in colour. e) A substance does not react with chlorine. f) A substance decomposes on hearting.

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Classify as : Physical or Chemical properties. a) Density b) Ability to burn c) Explosiveness d) Solubility e) Melting point f) Corrosiveness

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A PHYSICAL CHANGE This is a change which causes no change in

composition. E.g. the melting of ice

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A CHEMICAL CHANGE Is one which is accompanied by a change in

composition. It involves the disappearance of one or more

substances ( reactants) and the appearance of one or more new substance (product). These changes are referred to as CHEMICAL REACTIONS.

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Classify as : Physical or chemical changes. a) Freezing water. b) Rusting of Iron. c) Evaporation of dry

ice. d) Explosion of gun

powder. e) Tearing of paper.

f) Digesting of food. g) Absorption of a

vitamin from the intestinal tract.

h) Detoxification of a drug in the liver.

i) Synthesis of protein in muscle tissue.

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ENERGY Is the capacity to do work. It can not be destroyed. It can be converted from one form into another.

Gravitational potential energy to kinetic energy. Electrical to kinetic. Electrical to thermal (heat).

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A PURE SUBSTANCE This substance has a definite, invariable composition

and cannot be separated into simpler substance by physical means.

HOW IS IT TO DETERMINED WHETHER A SUBSTANCE IS PURE OR NOT ?

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A MIXTURE Is a combination of two or more substances in which

the substances retain their identities. i.e. there in no chemical reaction between their

components. The components may be separated by physical means

E.g. salt + water The components may be in any proportion

E.g. concentrated or diluted orange juice.

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A HETEROGENEOUS MIXTURE This mixture contain two or more phases. e.g

Sausage and cheese pizza Concrete Sand and water Oil and vinegar (salad dressing) Blood Milk of magnesia

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A HOMOGENEOUS MIXTURE This mixture contain only one phase e.g.

Sugar dissolve in water Air Metal alloys Gastric juice Spinal tap fluid

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Are the following classification a pure or as mixture? a) Copper b) Air c) Milk d) Water e) Concrete

f) Wine g) Sulphur h) Sugar solution i) Blood j) Urine

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Are each of the following mixture homogeneous or heterogeneous? a) Salt and pepper b) Alcohol and water c) Sulphur and iron d) Two different salts e) Milk of magnesia suspension f) 5% dextrose in water (used for injection)

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A MOLECULE It made up of atoms which are chemically bonded

together. It can be broken down into smaller units only if

chemical changes are allowed to take place.

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AN ATOM This represents the limits of chemical subdivision of a

molecule. E.g. pure substance can be divided into two classes.

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ELEMENTS Are pure substance composed of homoatomic

molecules i.e atoms of one type. e.g

Oxygen (O2) Iron (Fe) Carbon (C)

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COMPOUNDS Are pure substances composed of heteroatomic

molecules i.e two or more kinds of atoms. Carbon dioxide ( CO2) Suphuric acid ( H2SO4) Sodium chloride (NaCl)

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Classify these classes as heterogeneous mixture, homogeneous mixture, pure substance, compound, element. a) In which of these classes must two or more substance

present? b) Which of these classes could not possibly contain

heteroatomic molecules? c) A variable composition is possible for which of these

classes?

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Classify the following as: elements, compounds or no such classification

a) Analysis with some elaborate instruments indicates that substance A contains only aluminium atoms.

b) Substance B and substance C react to give a new substance D

c) Substance E decomposes on heating to give substance F and substance G.

d) Heating substance H to 800 degrees causes no change in it.

e) Analysis shows that substance I contains sulphur and oxygen.

f) Heating substance J to 620 degrees causes it to change from a solid to a liquid. PS Nkosi, Durban University of Technology, Department of Clothing and Textile Studies 25

Indicate whether each of the following statements is TRUE or FALSE. If it false, change it to make it true. a) Some pure substance may be decomposed into simpler

substances by chemical change. b) The smallest characteristic unit of a pure substance is an

atom. c) Molecules of pure substances are always heteroatomic. d) Heterogeneous mixtures can be separated into

component substance by physical means. e) In order for matter to be heterogeneous at least two

substances must be present. f) Pure substance can be variable composite. g) The limit of physical subdivision is a molecule. h) A compound contain only one type of molecule.

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PROPERTIES OF METALS Solid (one liquid – mercury) Shiny Malleable – can be pounded into sheets. Ductile – can be drawn into wires. High electrical conductivity. High thermal conductivity Oxides, if soluble, form alkaline solutions in water. Tend to form positive ions

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PROPERTIES OF NON-METALS Generally gases, some solids, one liquid Not shiny Not malleable nor ductile Poor conductors of heat or electricity Oxides, if soluble, form acidic solutions in water Tend to form negative ions.

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ATOMIC STRUCTURE AND PERIODIC TABLE.

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