Basic Concept of Chemistry - Chemistry
Topics: Thermodynamics
Subject: Chemistry
- Hydrocarbons
Subject: Chemistry
Topics: Basic Concept of Chemistry
Subject Code: CHM 4201
Lecturer: Mr. Jahedul Islam
Lecture No- 1 and 2
Basic Concept of Chemistry
Chemistry
is a branch of physical science that studies the composition, structure,
properties and changes of matter through reactions.
It
deals with the interactions of substances through inter molecular forces.
Chemistry
also includes the properties of individual atoms, how atoms form chemical bonds
to create chemical compounds.
And
the interactions between substances through chemical reactions to form
different substances
Chemicals
ÒChemical
Substances or Chemicals are form of matter that has
constant chemical composition and characteristic properties.
ÒIt
cannot be separated into components by physical separation methods, i.e.,
without breaking chemical bonds.
ÒChemical
substances can be chemical elements, chemical compounds, ions or alloys.
ÒChemical
substances exist as solids, liquids, gases, crystals or colloids etc.
ÒExamples
? Say yourself !!!!!!!!
Parts
of Chemistry
Organic
Chemistry
Inorganic
Chemistry
Physical
Chemistry
Another two parts of chemistry are,
ØAnalytical
ØChemistry
ØBiochemistry
Organic
Chemistry
Organic chemistry – Study of the
structure, properties, composition, mechanisms and reactions of organic
compounds that contain carbon
Or simply, the study of chemicals that
contain carbon.
Examples – Chemicals in living organisms,
Inorganic chemistry
deals with the properties, functions, synthesis and behavior of inorganic
compounds
Or simply, the study of chemicals that do
not contain carbon.
ÒExamples
– NaOH, KCl
etc.
Say yourself
ÒSulfuric
Acid H2SO4
ÒMethane CH4
ÒSodium Chloride NaCl
ÒGlucose C6H12O6
ÒHydrochloric
Acid HCl
ÒEthane C2H6
ÒCopper-sulfate CuSO4
Physical
Chemistry
ÒPhysical
chemistry – study of the physical and fundamental basis of chemical systems and
processes. Or,
ÒThe
study of :
ÉThe
mechanism
ÉThe
rate
ÉThe
energy transfer
ÉThermodynamics
ÉChemical
equilibrium etc.
with
the concept of physics, e.g., motion, force, energy, time etc. that happens
when matter undergoes change.
Biochemistry
ÒStudy
of processes that take place in organisms.
ÒChemistry
of living organisms.
ÒExamples:
Animals, Plants, Microorganisms etc.
Atoms
ÒAn atom is
the smallest particle or, constituent unit
of ordinary matter that has the properties of a chemical element.
ÒEvery
solid, liquid, gas
is composed of neutral or ionized atoms.
ÒAtoms
are very small; typical sizes are around
100 picometers (a ten-billionth of a meter)
Structure
of Atom
ÒThe
atom is composed of various subatomic particles.
The
constituent particles of an atom are the electron, the proton and the neutron
Chemical
Bonds
?
ÒIonic
bonds: Ionic bonding is a type of chemical bond
that involves the electrostatic attraction between oppositely charged ions.
ÒThe
ions are atoms that have gained one or more electrons (known as anions)
ÒAnd
atoms that have lost one or more electrons (known as cations).
Ø
Covalent bonds: A covalent bond, also called a molecular
bond, is a chemical bond that involves the sharing of electron pairs between
atoms.
Ø
These electron pairs are known as shared pairs or bonding pairs
or lone pairs.
Hydrogen
bonds: A
hydrogen bond is the electrostatic attraction between two polar groups that
occurs when a hydrogen (H) atom covalently bound to a highly electronegative
atom such as nitrogen (N), oxygen (O), or fluorine (F).
Molecule
ÒA molecule is
an electrically neutral group of two or more atoms held together by chemical
bonds.
ÒH2
Molecule → H••H → H-H
ÒH2O
Molecule → H••O••H → H-O-H
ÒCO2
Molecule → O : C : O → O-C-O
Elements
ÒA chemical element
is a species of atoms having the same number of protons in their atomic nuclei.
ÒAll
atoms of an element are same.
ÒThere
are 118 elements that have been identified,
ÒFirst
94 occur naturally on Earth with the remaining 24 being synthetic elements.
Periodic Table Chart
Compounds
ÒA
chemical compound is consisting of two or more atoms, at least two from
different elements, which associate via chemical bonds.
ÒThere
are few types of compounds, depending on bonds:
ØCovalent compounds: held
together by covalent bonds,
ØIonic compounds:
held together by ionic bonds,
ØIntermetallic compounds: held
together by metallic bonds.
Intermolecular
Forces
ÒInter-molecular
forces (IMFs) are the forces which mediate
interaction between molecules, including forces of attraction or repulsion
which act between molecules and other types of neighboring
particles, e.g., atoms or ions.
ÒSame
charged particle repulsion, opposite
charged particle attraction.
Solutes,
Solvents & Solutions
•A
homogeneous mixture, such as a glass of tea, is called a solution.
•Aqueous
solutions are solutions in which water is the solvent.
Solutes,
Solvents & Solutions
•Solute is the substance present in
the smallest amount.
•Solvent is the substance present in
the greatest amount.
•When sugar is added to a glass of
water, sugar is the solute and water is the solvent.
PH
Concept
•The
formal definition of pH is the negative logarithm of the hydrogen ion
concentration or activity of a particular solution.
•pH
= -log[H+]
•pH
is a unit of measure which describes the degree of acidity or alkalinity
(basic) of a solution.
•It
is measured on a scale of 0 to 14.
PH
Concept
ÒThe
pH value of a substance is directly related to the ratio of the hydrogen ion
and hydroxyl ion concentrations.
ÒIf
the H+ concentration is higher than OH- the material is acidic.
ÒIf
the OH- concentration is higher than H+ the material is basic.
Ò7
is neutral, < is acidic, >7 is basic
Acids and bases
• The pH is a measure of how
acidic (H+)
or basic (-OH) a solution is.
• A scale with values ranging from
below 0 to above 14 is used to measure pH.
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