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## Charle’s Law

This law states that the volume of a given mass of gas is directly proportional to its temperature in Kelvin, provided that the pressure remains constant. Where k is the constant of proportionality, and V and T are the volume and temperature of the gas respectively. ExperimentalJ.A. Charles (1787) investigated the relationship between the volume…

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## General Gas Equation

This general gas equation is obtained by a combination of Boyle’s law, Charles’ law and Avogadro’s law and can be expressed as Where                         PV   =     nRT                          P    =     Pressure                          V    =     Volume                          n    =     Number of moles                          R    =     Gas constant                          T    =     Temperature (Kelvin) NoteThe postulates discussed above apply to ideal gases. That is…

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## Gay Lussac’s Law

Our modern day balanced gaseous equations have their origin from Gay Lussac’s experimental findings. Consider the illustrations below. 1. 2. By similar consideration, one can explain the reaction between hydrogen and oxygen gas to form water vapour following the same argument.       The ratio of the volumes of the reacting gases above is:    Ratio…

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## Boyle’s Law

This law states that the volume of a given mass of gas is inversely proportional to its pressure provided that temperature remains constant. where k is a constant, P and V being the pressure and volume of the gas respectively. This law was verified using the apparatus shown in the Figure below. ExperimentalRobert Boyle (1627…

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## Graham’s Law

In 1833, Thomas Graham, an English chemist, in his experiments discovered that: 1. Gas molecules diffuse and fill up all available space mixing up with air molecules.Examples: i. Gradual spread of the smell of rotten eggs                      ii. Gradual spread of the smell of perfumes 2.  Different gases diffuse at different rates. Some gases are heavier…

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## The Kinetic Theory

The kinetic theory predicts a relationship between pressure of a gas and its temperature. Consider an inexpensive container filled with a gas. If the container is heated, the gas molecules will speed up and strike the walls of the container more frequently and with more force. Such action will increase the pressure. This implies that…

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Avogadro hypothesis confirmed as Avogadro’s law states that equal volumes of all gases at the same temperature and pressure contain the same number of molecules. 1 mole of any substance contains the Avogadro’s number of particles of that substance. particles (molecules, ions atoms, electrons) = Avogadro’s number. Example: In simple term, Avogadro’s law states that…

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## Types of Chemical Bonds

It will be recalled that the maximum number of electrons that can be found in any shell is 2n2 where n is the quantum number. Any atom whose outermost shell contains these maximum number of electrons is usually very stable and highly unreactive. The inert gases in group VIII (helium, neon, argon and krypton) always…

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## The Periodic Table

The periodic table is the arrangement of elements in a pattern that shows that elements with similar chemical properties appear at regular intervals or periods. As a result, elements in each vertical column have similar chemical properties and similar electronic configurations. Their atoms have the same number of electrons in their outermost shells. Elements arranged…

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## Electronic Configuration of Atoms

The nucleus consists of protons and neutrons while the proton is positively charged with a unit mass, the neutron also has a unit mass but with no charge. This means that the nucleus has a net positive charge with a mass equal to the mass of both the protons and the neutrons. The third particle…

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## The Constituents of the Atom: Proton, Neutron and Electron

Atoms are composed of protons, neutrons and electrons. A simple model of a hydrogen atom is shown in the below image. Electrons occupy shells surrounding the nucleus. The characteristics of each of these particles are described in this table READ MORE

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## Atomic Number, Mass Number, Isotopes, and Relative Atomic Masses of Atoms

Atomic numberThis is the number of protons (i e. number of positive charges) in the nucleus of any atom. Mass numberThis is the total number of protons and neutrons (collectively called nucleons) in the nucleus of the atom. IsotopesIsotopes are atoms of the same elements with the same atomic number but different mass numbers. The…

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## Arrangement of Electrons and the Nucleus

Electrons occupy shells (orbits) surrounding the nucleus. The shells are lettered K, L, M, N, O… and numbered 1,2, 3, etc., corresponding to energy levels. There is a limit to the number of electrons that can be found in a shell.The actual number is obtained by a formula , where n is the energy level.…

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## Relative Atomic Mass

A natural sample of an element is a mixture of isotopes with different mass numbers. The average mass of these atoms in a naturally occurring sample is called the relative atomic mass of the element. Thus we can obtain the relative atomic mass of chlorine known to have chlorine -35 and chlorine -37 isotopes occurring…

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## Symbols, Formulae and Equations

Chemical SymbolsA chemical symbol is an abbreviation that chemists use to represent atoms of an element. Symbols of some elements are derived from the common names of the element while others are derived from their names in other languages. Most symbols have one or two letters. The recently synthesised (prepared) elements use three- letter symbols.…

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## Empirical Molecular Formulae and Chemical Equations

The empirical formula is the simplest formula of a compound which gives the simplest whole-number ratio of atoms of the combining elements. Example is the formula of the compound benzene. The molecular formula of benzene is C6H6. This can be written in its simplest form as CH. Thus CH is the empirical formula of benzene.…

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## The Concept of Atom and Molecule

Matter is made up of discrete particles namely, atoms, molecules and ions. AtomAn atom is the smallest particle of an element which can take part in a chemical reaction. Examples are C, O and H. MoleculeA molecule is the smallest part of a substance that can exist independently. It is formed by a chemical combination…

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## Particulate Nature of Matter

– Matter is made up of discrete particles namely atoms, molecules and ions. – Atom is the smallest particle of an element that can take part in a chemical reaction. – A molecule is the smallest part of a substance that can exist independently. – Atoms are composed of protons, neutrons and electrons. – Electrons…

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## Laws of Conservation of Matter, Constant Proportion and Multiple Proportion

Early history of chemistry was marked by incorrect theories about what occurred during chemical reactions. It had long been observed, for instance, that when wood burnt, the resulting ash was very light and fluffy. These types of observations then led to the conclusion that ‘something’, which German chemists, Becher and Stahl called phlogiston, was lost…

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## Separation of Substances

Nature of matter Matter is anything that has weight and occupies space. This definition implies that substances found around us are all forms of matter. Substances exist either as solids, liquids or gases, each with its distinctive local or scientific name. Examples of solids are tables, books, ice block and iron filings; water, kerosene and…