Introductory Chemistry B CH4751 Dr. Erzeng Xue CH4751 Lecture Notes 1 (Erzeng Xue)

Introductory Chemistry B CH4751

Dr. Erzeng Xue

CH4751 Lecture Notes 1 (Erzeng Xue)

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Course General Information

Lectures Room: C1061

Time: Monday 5pm, Tuesday 2pm

Notes: Available at the class and on the UL’s web

Labs Room: B3-053,

Time: Friday 4pm, Weeks 3, 5, 7, 9, 11

Attendance is MANDATORY

MUST have white lab coat and safety specs

Assessment 75% End term Exam

25% Lab. Attendance/Reports


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CH4751 Course Syllabus Fundamental Laws, Dimensions and Units of Measurement Matter, Composition, Structure and Properties

Classification and Composition Atoms, Molecules & Ions Chemical Bonding Periodic Nature of elements The mole: definition and use

Change in Composition and Structure - Chemical Reactions Reaction Process and Types of Reaction Reaction Stoichiometry Direction of a Reaction and Energy Change Associated with it The Extent of Reaction and Chemical Equilibrium Rate of Reaction and Concept of Catalysis

Chemistry of Selected Systems Chemical Reactions Involving Multi Phases Acid, base and pH Quantum Chemistry & Its Applications in Chemical Modelling & Spectroscopes Chemistry in Specialised Areas Introduction to Organic Chemistry / BioChemistry (depending on the availability of time)



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Recommended Texts

Available in UL Bookshop as follows: Brown, LeMay & Bursten, “Chemistry: The Central Science”, 9th ed.

Zumdahl, “Chemistry” 5th ed.

Atkins & Jones, “Chemistry: Molecules, Matter, and Change”, 3rd edn.

Available in UL library General Chemistry texts – Classification Number 540



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ExperimentsThere are 5 experiments

1. Separation of sand and salt

2. Assay of an industrial Etchant solution by acid-base titration

3. A series of reactions involving compounds of copper

4. The oxidising capacities of household bleaches

5. Indicators and acid-base dissociation constants


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What Is Chemistry ?

Describes: Structure & composition of matter (at both macro and micro levels)

Changes in structure & composition

Energy involved in these changes

Why Study Chemistry ?

Understand our world and how it works

Chemistry is the central science

‘Educate’

This module is the foundation course on which you can further build up your knowledge of chemistry in other areas


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How To Study Chemistry ? Fundamental laws

Using clear language Clear definition of terms used logic description of known facts

Using scientific methods Observation of true fact Carefully designed experiments Modelling Classification of known information

observation

hypothesis

Scientific law

experiment

prediction

Do results agree with

hypothesis?

Modify hypothesis

No

Yes


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Where Are You Standing Now?

Your Leaving Cert

Chemistry Knowledge

Targeted

Your Chemistry Knowledge

After CH4751


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Fundamental laws

Law of Conservation of Energy

Energy can be neither created nor destroyed, but may be transformed from one form to another

Law of Conservation of Mass

Mass cannot be created or destroyed. The total mass of substances involved in a physical or chemical change remains constant


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Dimensions and Units

DIMENSON

Many things happening in a process (naturally or in an experiments) What are these things or quantities?

How many quantities are involved? Are these quantities dependent or independent?

UNIT

What is the scale of a quantity (big or small)? To describe a quantity quantitatively To compare the same quantity

at different stage of a process, or in two different processes

Dimension and unit provide the base of ‘scientific language’


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Fundamental Dimensions

There are 7 independent dimensions


Dimension Definition Symbol Unit (S.I.) Unit (English)

Mass quantity of matter in a body M g (gram) lb (pound)

Length measurement of distance L m (meter) ft (foot)

Time measurement of progress of an event s (second) s (second)

Temperature The condition of a body which determines

the transfer of heat to or from that body

K (Kelvin)

°C (Celsius)

°F (Fehrenheit)

°R (Rankine)

Amount of substance

The number of specified entities of a pure

substance

N mol mol

Electric Charge Rate of transfer of electricity Q A (ampere) A (ampere)

Luminous intensity

Rate of transfer of light energy I cd (candela)

cd (candela)

Note: There are several unit systems in use. The most commonly used ones are S.I. (preferred) and English.


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Use of Dimensions and Units

All other quantities can be expressed in terms of these fundamental quantities For complex situation derived units may be used

e.g. velocity would have dimension LT-1

For each dimension unit can be in different scale

e.g. velocity would have unit: m/s, km/hr etc. An unit for the same dimension in different systems can be converted

e.g. velocity 120 miles/hr = 195.6 km/hr = 3260 m/min

A quantitative description consists of 2 parts

number + unit e.g. velocity: 10 m/s, the number used is depending on the unit used.

Different dimensions cannot be added, subtracted or equated



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Derived Units

A combination of different quantities representing a physical measurement can be expressed by using a Derived Unit

Quantity Definition Derived Unit

Area Length x length m2

Volume Area x length m3

Density Mass / unit volume kg m-3

Speed Distance / unit time m s-1

Acceleration Change in speed / unit time m s-2

Force Mass x acceleration kg m s-2 (Newton, N)

Pressure Force / unit area kg m-1 s-2 (Pascal, Pa)

Energy Force x distance kg m2 s-2 (Joule, J)



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Unit Conversion

Procedure of unit conversions:a) Find equivalent of the unit:

e.g. 1 inch = 2.54 cm (Equivalence Statement)b) Write the unit factors:

e.g. (2.54 cm/1in) and (1 in/2.54 cm)c) Use proper unit factor in your calculation

e.g. A pencil is 7 inches long. What’s its length in cm?

7 in x (2.54 cm/1in) = 17.8 cm

Exercises: 1. A gas is at pressure of 29.7 psi, what is the pressure in atm? Write the conversion process.

2. When 1 litre of water at 20 °C is heated to 100°C, what is the volume of water vapour formed at 1 atm at 100°C? 3. A temperature of 104 Fehrenheit was read. What is this temperature in Celsium scale?



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Important Notes

When quoting any quantity always quote both the number and unit A number without unit has no definite meaning in physics and chemistry

When performing calculation always use the same unit system If the date collected contain the quantities in different unit system, make

conversion so that all the quantities are described in the same system before further calculation

Check the unit of a quantity before performing a calculation Only the numbers with the same unit can be added, subtracted and

equated



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Uncertainty in Measurement

Uncertainties always exist in measured quantities Caused by equipment errors, human errors

Accuracy: measure of how close measurement is to its real (or true) value

Precision: measure of how close successive measurements are to each other

Precise measurements can be inaccurate



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Matter and Its Classification

Matter

Physical state(appearance)

solid

Chemicalcomposition

mixture

liquid

gas (vapour)

pure substance

element

compound


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Physical State and Examples

Solid rigid, fixed volume and shape

Liquid definite volume but no distinct shape

Gas (vapour) no fixed volume or shape; conforms

to that of its container

CompressibilityChange in volume under pressure Solids and liquids are only slightly

compressible Gases are highly compressible

Matter & its classification

Plutonium

Mercury

Chlorine


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Chemical Composition and Examples

Pure substance It has a definite chemical composition and properties.

It cannot be separated into simpler substances by physical means.

Element

pure substance which cannot be further broken down by ordinary chemical means.

Compound

pure substance which is composed of 2 or more elements and can be further broken down by chemical means.

Mixture contains 2 or more pure substances, which can be separated

out by physical means. can be homogeneous (uniform throughout, e.g. air) and

heterogeneous (not uniform throughout, e.g. wood)

Matter

carbon

ice

agate bronze



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Comparison: Mixtures vs. Compounds Differences between a mixture and a compound

Mixture Compound

Separation by physical techniques

Yes. No.

Composition Variable Fixed.

Properties Depending on the composition as well as the ratio of each

compounds in the mixture

Fixed.


Examples

Which of the materials below are pure substances and which are mixtures? What is physical states of each under normal conditions?

water, salt, paper, milk, apple, vegetable oil, petrol, cotton, vitamin tablets, natural gas, soil, beer, wine.


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Matter and Its Properties

Q1. Where can one get physical /chemical properties of a substance?

physical chemistry handbooks.

Q2. Why are physical/chemical properties different?

The composition & structure

Q3. Are there theories to explain/help us to understand the different properties of various substances?

Yes. The structure of atoms of constituent elements and how these atoms are stuck on each other in a molecule (chemical bonding).

Matter

Physical properties

Some examples are:state (solid, liquid, gas)melting/boiling point,thermoconductivity, density, etc

Chemical properties

Some examples are: reactivity, corrosive natureacidity/basicity,toxicityetc.


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Atoms and Molecules

AtomSmallest particle of an element which can undergo chemical changes in a reaction

Note: Atom - we mean each individual ‘particle’ of an element (microscopic)

Element - we mean the collective of atoms of the same kind (macroscopic)

MoleculeSmallest particle of a compound which can exist and still retain the chemical properties of the compound.

Note: Molecule can be a single atom or several atoms binding each other in a specific way

Molecule - we mean each individual ‘particle’ of a compound (micro-)

Compound - we mean the collective of molecules of the same kind (macro-)


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Structure of the AtomsAtoms & Molecules

Nucleus - consists of protons and neutrons

Some basic fact about the atom

Size: 0.1 to 0.5 nanometers (1 nm =1x10-9 m)

Composition: contains electrons (e), protons (p), and neutrons (n), with the exceptionof hydrogen.

Mass: H atom = 1.67x10-24g

= 1.008 atomic mass units (a.m.u.)

C atom = 2x10-23g = 12.000 a.m.u.

Electrical charge: neutral

particle mass (a.m.u.) charge e- 0.0005 - 1 p+ 1.007 +1 n 1.009 0

~ 5x10-15 m

~ 0.1- 0.5 x 10-10 m

Electron clouds


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Structure of the Atoms Important points

The number of electrons & protons in an atom are equal - zero net electrical charge The nucleus of an atom is very small in comparison with the overall size of an atom Density of the nucleus of an atom is huge (of the order of 1013-1014 g/cm3) because:

the nucleus carries most of the atom’s mass (protons & neutrons) in its tiny volume Electrons take up most of the volume of the atom and play the key role in chemical

reactions

Comparison of Atom Size with everyday objects

Q1. The diameter of a carbon atom is 1.5 x 10-10 m. How many carbon atoms could be aligned side by side in a straight line across the width of a pencil line that is 0.2mm wide?

A. 0.2 x 10-3m/ 1.5 x 10-10m = 1.3 x 106 C atoms

Q2. The diameter of a 2 cent coin is 19 mm while the diameter of a silver atom is 2.88x10-10 m. How many silver atoms could be arranged side by side in a straight line across the diameter of it?

A. 19 x 10-3m/ 2.88 x 10-10m = 6.6 x 107 Ag atoms

Atoms & Molecules


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Atom Atom - individual ‘particle’.

- We say a hydrogen atom, a chlorine atom Element

Collective of atoms of the same kind. Each element is given a specific symbol. Usually the symbol is taken from the 1st

one or two letters, with some exception such as iron-Fe, gold-Au, silver-Ag, etc.

Some of the more common elements

Element Symbol Element Symbol

Hydrogen H Helium HeCarbon C Aluminium AlNitrogen N Oxygen OPhosphorous P Iron FeCopper Cu Nickel NiSulphur S Iodine I

Atoms and Elements Atoms & Molecules


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Molecules and Compounds Molecule

It can be a single atom or several atoms ‘stuck on’ (chemical bond) each other in a specific way.

E.g. We say carbon molecule, C, chlorine molecule, Cl2, water molecule, H2O.

The properties of a molecule are related to the constituent atoms but also depending on how these atoms are bonded together

Atoms are the basic building blocks for molecules

Compound Collective of molecules of the same kind.

We say hydrogen (compound), H2, chlorine (compound), Cl2, water, H2O etc.

Q. What we call CO, an atom? an element? a molecule? a compound?

Atoms & Molecules


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Elements A How many elements are there?

So far we have identified around 120 (some of them exist only a short time in lab(Note: we don’t say how many atoms we found. it depends on the quantity of an element)

How many compounds are there? Many, many. There are more new compounds found and invented

(Note: We don’t say how many molecules we found. its number depends on the quantity of a compound)

Atoms & Molecules


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Periodic Table of Elements Different element refers different matter - are there any relation/trend?

Yes. they can be arranged according to their atomic mass & electronic structure Periodic table of elements showing the atomic number

Atoms & Molecules

Cl17

35.45

Symbol of element

atomic numberatomic mass

Note: - The symbols used for elements

are universally adapted. - There are different notation

systems in use. Check the keys.


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Isotopes and Atomic Mass

Isotopes Atoms of the same element having different no. of neutrons, thus different masses

e.g. hydrogen deuterium tritium

molecules consist of atoms having different no. of eutrons are also called isotopes. Atomic mass

is the average of the isotope masses of an element, weighted to reflect their relative natural abundancesExample: Chlorine has two naturally occurring isotopes, 35Cl (A=34.97a.m.u.) and 37Cl (A = 36.96 a.m.u.). The respective natural abundances of these isotopes are 75.5% and 24.5%.

(average) atomic mass

Note: atomic mass is also called as atomic weight

Atoms & Molecules

neutron) 1 &proton (1 H21proton) (1 H1

1 neutron) 2 &proton (1 H31

(a.m.u.) 4535100

24.5)(36.9675.5)(34.97.


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Atoms, Molecules and Ions

Ions In some situations (in a chemical reaction or an acid/base dissolved in water),

atoms or molecules have gained or lost one or more electrons.

e.g. H+ OH- SO4= (or SO4

-2)

Ions can carry positive charge when lost electrons, e.g. H+

Ions can carry negative charge when gained electrons, e.g. OH-, SO4=

Note: the superscript refers to the number of electrons gained or lost.

Atoms & Molecules


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Inter-Conversion ChartAtoms & Molecules

Elements Compounds

Atoms Molecules

Ions Isotopes

Identicalatoms

± e-± n

± e- ± n


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Molecule Mass

Molecular mass is the sum of the atomic masses of all of the constituent atoms in a molecule.

Example 1: Molecular mass (M.M.) of H2?

Atomic Mass (A.M.) of H = 1.008 a.m.u.

M.M. of H2 = 2 x 1.008 = 2.016 a.m.u.

Example 2: M.M. of carbon monoxide, CO?

A.M. of C = 12.0 a.m.u., A.M. of O = 16.0 a.m.u

M.M. of CO = 1x12.0 + 1x16.0 = 28.0 a.m.u.

Example 3: M.M. of glucose, C6H12O6?

A.M. of C=12.0 a.m.u., A.M. of H is 1.0 a.m.u., A.M. of O=16.0 a.m.u

M.M. of C6H12O6 = 6x(12.0 a.m.u.) + 12x(1.0 a.m.u.) + 6x(16.0 a.m.u)

= 180.0 a.m.u.

Note: molecule weight (unit g/mol) equals to molecule mass in value but refers to a different unit.

Atoms & Molecules


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A chemical bonding

refers to a specific way atoms are held together in a molecule by certain forces A chemical reaction always involves bond reconstruction (in most cases bond-

breaking and reformation)

The properties of a resultant molecule depend not only on those of constituent atoms but also how they are bonded together

An atom may form one type of bond with certain atoms and another type bond with other type of atoms, depending on the nature of the bonding atoms

Types of chemical bonds Ionic

Covalent

Dative (or coordinate) covalent

Atomic structure, especially the orbital theory, is the basis of chemical bonding

Chemical Bondings


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Classical Orbital Theory An atom can have several shells of

electrons, spinning around nucleus (n=1, 2, 3 etc)

There is a maximum number of electrons each shell can hold

Electrons at each shell has different level of energy, those at outer shell having higher energy

When excited (absorb energy) an electron can jump from lower orbital to higher orbital, which is unstable - the electron then jumps back to its original orbital and release energy in various forms (spectroscopes)

Chemical bondings

En

erg

y

n=1

n=2

n=3

n=4

1s2s2p

3s3p

4s3d4p

4d4f

n = 1

n = 2

n = 3, etc.

Nucleus

energy

energy


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Electronic Configuration and Periodic Table of Elements

Electronic configuration-distribution of electrons among each shell of an atom Different elements have different electronic configurations Periodic Table and Electronic configuration

The row (period): number rows corresponding to the number of shells The columns (group): generally representing the number of electrons at outer shell

Chemical bondings


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Electronic Configurations of Elements

Element Atomic number Electrons in each shell Electron configuration n=1 n=2 n=3 n=4

Hydrogen 1 1 1s1

Helium 2 2 1s2

Lithium 3 2 1 1s2, 2s1

Beryllium 4 2 2 1s2, 2s2

Boron 5 2 3 1s2, 2s2, 2p1

Carbon 6 2 4 1s2, 2s2, 2p2

Nitrogen 7 2 5 1s2, 2s2, 2p3

Oxygen 8 2 6 1s2, 2s2, 2p4

Fluorine 9 2 7 1s2, 2s2, 2p5

Neon 10 2 8 1s2, 2s2, 2p6

Sodium 11 2 8 1 1s2, 2s2, 2p1, 3s1

Magnesium 12 2 8 2 1s2, 2s2, 2p1, 3s2

Aluminium 13 2 8 3 1s2, 2s2, 2p1, 3s2, 3p1

Silicon 14 2 8 4 1s2, 2s2, 2p1, 3s2, 3p2

Phosphorus 15 2 8 5 1s2, 2s2, 2p1, 3s2, 3p3

Sulphur 16 2 8 6 1s2, 2s2, 2p1, 3s2, 3p4

Chlorine 17 2 8 7 1s2, 2s2, 2p1, 3s2, 3p5

Argon 18 2 8 8 1s2, 2s2, 2p1, 3s2, 3p6

Potassium 19 2 8 8 1 1s2, 2s2, 2p1, 3s2, 3p6, 4s1

Calcium 20 2 8 8 2 1s2, 2s2, 2p1, 3s2, 3p6, 4s2

Chemical bondings

shell numbern=1,2,3,4 etc

type of orbitals,p,d,f

number e-’sin that orbital


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Chemical Bonding and e-1 Configurations General Rule of bond formation

Atoms of an element participating in bonding usually try to achieve a closed outer shell (low energy) e- configuration as a result of bond formation

e.g.'s: Li (1s2 2s1) prefers to be Li+ (1s2) by losing 1 electron

Mg (1s2 2s2 2p6 3s2) prefers to be Mg2+ (1s2 2s2 2p6) by losing 2 electrons

F (1s2, 2s2, 2p5) prefers to be F- (1s2 2s2 2p6) by gaining 1 electron

Simple Representations of Chemical Bonds: Electron-Dot (Lewis Structures) Rules:

outer shell e- 's only element symbol represents "core“ single dots on each side, then pair to a maximum of 8, exception He

Note: only works for elements with a max. of 8 e- 's in outer shell (i.e. not suitable for d orbitals)

e.g. Mg, electron configuration: 1s2, 2s2, 2p6, 3s2 Lewis structure: Mg

Chemical bondings


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Ionic Bonding Involves complete transfer of e- '(s) from one atom to the other.

How many e- 's transfer ? Depends on:

number required to leave a filled outer shell energy considerations (ionisation vs. bond formation)

Electrostatic forces are involved (attraction of opposite charges).

Consider formation of sodium chloride, NaCl:Nao + Clo Na+Cl-

1s2,2s2,2p6,3s1 1s2,2s2,2p6,3s2,3p5 (1s2,2s2,2p6)+ (1s2,2s2,2p6,3s2,3p6)-

closed shell e- configurations

Electron-Dot representation

Na . + . Cl: Na+ [ :Cl: ]-

Chemical bondings

..

..

..

..


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Covalent Bonding Involves sharing of outer shell e- '(s) between atoms, allowing each atom

to have a ‘full shell’ of electrons

Driving force same as for ionic case: overall decrease in energy of system i.e. energy is evolved during bond formation

A pair of shared e-s form a single covalent bond (2 pairs of shared e-s form a double covalent bond, 3 pairs form triple bond)

Most of gas molecules are covalent bonded

e.g. hydrogen:

H . + . H H : H (1 pair shared e-s, single covalent bond, written as H-H or H2)

oxygen:

:O: + :O: O::O (2 pairs shared e-s, double covalent bond written as O=O or O2)

Note: In electron dot structures of covalent molecules, shared electrons placed between symbols, electrons which are not shared are retained beside symbol for that atom.

Chemical bondings

.

.

..

..

.

.

..

..


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Ionic bonding

Cao + 2 Clo CaCl2

1s22s22p63s23p64s2 + 1s22s22p63s23p5 1s22s22p63s23p6 + 1s22s22p63s23p6

(Ca2+) (Cl-)

Closed shell e- configuration Electron Dot

Ca: + .Cl: + . Cl: Ca2+ [ :Cl: ]- [ :Cl: ]- (Calcium chloride CaCl2)

Covalent bonding

N0 + N0 N2

Electron dot: . N . + . N . N:::N N N

3 pairs of electrons shared forming a triple bond

More ExamplesChemical bondings

..

..

..

..

..

..

..

..

..

....

...

.


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Dative Bonding

It is a special type of covalent bond - the pair of e-’s shared are supplied by one of the constituent atoms (instead of supplied by both atoms)

Example: NH3 + H+ NH4+

H H +

H : N : H+ H : N : H

H (hydrogen ion, lost e-) H

The driving force is the desire to complete the 1s orbital of hydrogen

Chemical bondings

..

..

..

..these pair of e-’s are supplied by N atom


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Summary so far:

In a chemical bond, atoms or ions are strongly attached to one another Use of Electron-Dot or Lewis structures

Ionic bonding involves complete transfer of electrons from one atom to the other

e.g. NaCl

(metal with a low ionisation energy, non-metal with a high electron affinity)

Covalent bonding Involves sharing of outer shell e- 's between atoms. Depending on the number pairs of shared e-’s, it can be a single covalent bond

(e.g. H2, single pair of e- 's ), double (O2) and triple bonds (N2).

Dative (coordinate covalent) bond - shared e-’s supplied from one atom

Summary of Chemical BondingsChemical bondings


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Electronegativity and Bond Polarity

In the cases of H2, O2 and N2, the constituent atoms in molecule are the same, the shared e-’s form shell that is symmetry

When the constituent atoms are different, because the force attracting e-’s may be different, as a result of it the shell will be non-symmetry - polar covalent bond.

e.g. HCl Ho + Clo HCl (1s1) (...3s23p5)

Chlorine attracts e-’s more strongly than hydrogen Bonding in HCl is intermediate between ionic & covalent since e-’s are not evenly shared.

Electronegativity: ability of an atom in a molecule to attract electrons to itself Related to electron affinity and ionisation energy, which vary with atoms A highly electronegative atom has

a very negative electron affinity, i.e. it attracts electrons from other atoms a high ionisation energy, i.e. it resists having its own e-’s attracted away to other atoms

The different atoms have different electronegativity. Trend in the Periodic Table Increase from left to right decrease down a group

Chemical bondings

H H :

HCl:


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Electronegativity and Bond Polarity

A value is assigned to each atom for its electronegativity. The higher the number is the more electronegativity is.

The difference in electronegativity of atoms in a molecule can be used to predict the type of bonding between them - the higher difference, more polar the molecule….

Examples:

F2 Electronegativity difference: 4.0(F)-4.0(F)=0 Nonpolar covalent bond

HF Electronegativity difference: 4.0(F)–2.1(H)=1.9 Polar covalent bond (H+ F-)

LiF Electronegativity difference: 4.0(F)–1.0(Li)=3.0 Ionic bond (Li+ F-)

Exercises 1. Which bond is more polar? B-Cl or C-Cl

B-Cl EN Diff: 3.0(Cl)-2.0(B)=1.0

C-Cl EN Diff: 3.0(Cl)-2.5(C)=0.5 Answer: B-Cl bond is more polar

Exercises 2: Which bond is most polar? S-Cl, Se-Cl or Se-Br?

S-Cl EN Diff: 3.0(Cl)-2.5(S)= 0.5

Se-Cl EN Diff: 3.0(Cl)-2.4(Se)=0.6

Se-Br EN Diff: 2.8(Cl)-2.4(Se)=0.4 Answer: Se-Cl bond is most polar

Chemical bondings

this symbolindicate that e-’s density is more closer to F atom


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More about Bond Polarity

The electronegative difference of the constituent atoms makes a molecule polar

Many properties of substances are related to the polarity of molecules through the electrostatic force generated by the polarity

The extend of polarity of molecules can be quantified by using dipole moment, which is the product of charge multiplying by distance.

Some other terms frequently encountered when talking about bond

Bond length - the distance between bonding atoms

Bond strength - how strong the bonding atoms can be held by the bond

Bond angle - geometrical orientation of bonds when an atom forming more than one bonds with surrounding atoms

Chemical bondings

HCl: HCl:

positive end negative end

e.g. the positive end attracts negative end resulting in an ordered arrangement or specific affinity between substances


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Periodic Table of Elements Originally proposed by Mendeleev in 1869 according to the atomic weights as

well as the periodic features of element in their physical & chemical properties. Modern P.T is arranged according to electronic configuration of elements. Rows (one row per principle quantum level of shell) Column (group) the elements having the same outer e-’s.


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More about Periodic Table of Elements

Main groups 1A to 8A

group 1A: Alkali metals e.g. Na

group 2A: Alkaline earth metals e.g. Mg

group 7A: Halogens e.g. Cl

group 8A: Noble gases e.g. Ne

Group 1B to 8B - transition elements

Metal and non-metals

metals: left and middle (except hydrogen)

metalloid:

non-metal:


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More about Periodic Table of Elements

Many other properties of elements show periodic feature. Some examples:

Atomic radius (distance between the nuclei of atoms in a chemical bond)

Decrease from left to right within a row and increase from up to down in a group

First ionisation energy (energy required to remove the first e- from a neutral atom)

Increase from left to right within a row and decrease from up to down in a group

Electron affinity (energy change associated with the addition of an e- an atom)


Electronegativity


etc.


Introductory Chemistry B CH4751 Dr. Erzeng Xue CH4751 Lecture Notes 1 (Erzeng Xue)

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Transcript of Introductory Chemistry B CH4751 Dr. Erzeng Xue CH4751 Lecture Notes 1 (Erzeng Xue)