Chemistry LECTURE SHEET Eng. Vershion
1)
Insoluble: When a solvent fails to dissolve a solute completely, leaving some
portion of the solute undissolved, it is called insoluble. Examples include
sand, chalk, glass, plastic, rubber, wood, and certain metals like copper and
iron.
2)
Symbol:
The abbreviated representation of an element is called its symbol. For example,
the symbol of Bromine is Br, and the symbol of Boron is B.
3)
Insoluble Compounds: Compounds that do not dissolve in water are called insoluble compounds.
Examples include barium sulfate, silver chloride, and lead sulfate. These
compounds remain undissolved in aqueous solutions and form precipitates.
Important
facts about atoms:
û
Basic Unit of Matter – Atoms are the fundamental
building blocks of all matter.
û
Atomic Structure – An atom consists of a nucleus
containing protons and neutrons, surrounded by electrons in orbitals.
û
Protons, Neutrons, and Electrons – Protons are
positively charged, neutrons have no charge, and electrons are negatively
charged.
û
Atomic Number – The number of protons in an atom
determines its atomic number and identity.
û
Mass Number – The sum of protons and neutrons in the
nucleus gives the mass number of an atom.
û
Electron Shells – Electrons are arranged in energy
levels or shells around the nucleus.
û
Isotopes – Atoms of the same element with different
numbers of neutrons are called isotopes.
û
Ions – When an atom gains or loses electrons, it
becomes an ion, carrying a positive or negative charge.
û
Chemical Bonds – Atoms form molecules and compounds
through chemical bonds like ionic, covalent, and metallic bonds.
û Periodic Table – Elements are arranged
in the periodic table based on their atomic number and properties.
û Bohr Model – Proposed by Niels
Bohr, it describes electrons moving in fixed orbits around the nucleus.
û Quantum Model – Modern atomic theory
suggests electrons exist in probabilistic electron clouds rather than fixed
orbits.
û Radioactivity – Some atoms undergo
radioactive decay, emitting radiation as they transform into more stable forms.
û Nuclear Energy – Atoms can release
enormous energy through nuclear fission (splitting) or fusion (combining).
û Law of Conservation of
Mass –
Atoms cannot be created or destroyed in a chemical reaction, only rearranged.
The Structural Particles of an Atom are:
1. Proton (p⁺) – Positively charged particle located in the nucleus.
2. Neutron (n⁰) – Neutral particle (no charge) also found in the nucleus.
3. Electron (e⁻) – Negatively charged particle that orbits around the nucleus.
These fundamental particles determine the chemical and physical
properties of an atom.
Important
Information About Molecules
û Definition:
A molecule is the smallest unit of a compound that retains its chemical
properties.
û Composition:
Molecules are made up of two or more atoms chemically bonded together.
û Types of Molecules:
They can be diatomic (O₂, H₂), polyatomic (H₂O, CO₂), or macromolecules
(DNA, proteins).
û Chemical Bonds:
Molecules are held together by covalent, ionic, or hydrogen bonds.
û Molecular Formula:
Represents the number and type of atoms in a molecule (e.g., H₂O, CO₂).
û Structural Formula:
Shows the arrangement of atoms within a molecule.
û Polarity:
Molecules can be polar (H₂O) or non-polar (O₂, CH₄) based on the
distribution of electrons.
û States of Matter:
Molecules exist in solid, liquid, or gaseous states depending on
temperature and pressure.
û Chemical Reactions:
Molecules undergo chemical changes through reactions like combustion,
oxidation, and hydrolysis.
û Biological Importance:
Essential molecules like proteins, carbohydrates, lipids, and nucleic acids
are vital for life processes.
û Intermolecular Forces:
Molecules interact through van der Waals forces, dipole-dipole interactions,
and hydrogen bonding.
û Avogadro’s Number:
1 mole of any substance contains 6.022 × 10²³ molecules.
û Molecular Mass:
The sum of atomic masses of all atoms in a molecule, measured in atomic mass
units (amu).
û Reaction Stoichiometry:
Chemical reactions follow the law of conservation of mass, meaning the
total number of molecules remains constant.
û Nano-Molecules:
Some molecules, like fullerenes and carbon nanotubes, have unique
applications in nanotechnology.
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Chapter-8
Chapter-9
Chapter-10
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