Posts

JSS 1: NON-METALS

-
Image
Non-metals are elements that ionize by electron gain. They are usually poor conductors of heat and electricity, brittle, and often exist as gases, liquids, or dull solids at room temperature. Examples of Non-Metals Some common non-metals include: I. Hydrogen (H) II. Oxygen (O) III. Nitrogen (N) IV. Carbon (C) V. Sulphur (S) VI. Phosphorus (P) VII. Chlorine (Cl) VIII. Fluorine (F) IX. Iodine (I) X. Bromine (Br) etc       Physical Properties of Non-Metals 1. Non-metals are brittle when solid (i.e. they break easily). 2. They are poor conductors of heat and electricity (except graphite). 3. They usually have low melting and boiling points. 4. Many are gases at room temperature (e.g., oxygen, nitrogen). 5. Solid non-metals are dull in appearance (not shiny). 6. They have low density (i.e. light in weight). 7. They are non-sonorous (do not produce ringing sound when hit).   Chemical Properties of Non-Metals 1. Non-metals gain electrons to form negative...
Post a Comment
Read more

JSS 3: RADIOACTIVITY

-
Image
Radioactivity  is the spontaneous emission of radiation from the nucleus of an atom.                 Radioactive elements Examples of radioactive elements include: 1. Uranium (U) 2. Radium (Ra) 3. Thorium (Th) 4. Polonium (Po) 5. Actinium (Ac) etc                   Types of radiation  There are three main types of radiations emitted during radioactive decay: I. Alpha (α) rays II. Beta (β) rays III. Gamma (γ) gamma             Properties of Alpha Rays (α) 1. Alpha rays are positively charged particles made up of two protons and two neutrons (same as a helium nucleus, ⁴₂He ). 2. Each alpha particle carries a +2 charge. 3. They are heavy compared to beta particles and gamma rays. 4. They travel at a low speed (about one-tenth the speed of light). 5. They have very high ionizing power 6. They have low penetrating power. They can be stopped by a sheet ...
Post a Comment
Read more

SSS 2: ENERGY AND CHEMICAL REACTION

-
Image
Energy can be defined as the capacity to do work.                        Forms of Energy The different forms of Energy are: 1. Mechanical energy  2. Chemical energy  3. Electrical energy  4. Heat energy  5. Nuclear energy  6. Light (Photon) energy  7. Sound energy  8. Magnetic energy  All matter possess energy in one form or the other. When energy changes from one form to another, the total amount of energy before and after the change are always the same. This is the law of conservation of energy.         The law of conservation of energy states that energy can neither be created nor destroyed but it can be changed from one form to another.       Energy changes in chemical reactions Energy changes occur during chemical reactions because the reactants and products possess different amounts of chemical energy. The forms of energy changes that m...
Post a Comment
Read more

SSS 2: ELECTRODE POTENTIAL

-
Image
Electrode Potential is the potential difference set up between a metal and the solution of its salt.         When a metal is dipped into a solution containing its ions, there is a tendency for ions to move between the metal and the solution. This creates an electric potential difference between the metal and its ionic solution called the electrode potential.        The redox potential of a metal is the e.m.f which is measured in volt          The following equilibrium is established when a metal is dipped into a solution containing its ions. Metal(s)  ⇌ Metal ion  + electron   M(s)       ⇌      M⁺        +      e⁻ (plate)          (solution)      (plate)               Metal ions/ metal system                 ...
Post a Comment
Read more

SSS 2: ELECTROCHEMICAL SERIES

-
Image
                        ELECTROLYSIS  Electrolysis  can be defined as the process by which a solution or a molten substance is broken down into its components parts by the passage of electric current.               A simple electrolytic cell Electrolytic cell is an assembly of two electrodes in an electrolyte. It is used for the electrolysis of a substance             Basic Terms in Electrolysis 1. Electrolyte : A solution of acids, bases, salts or substances in molten state that can conducts electricity and is decomposed by it.                   Types of electrolytes There are two types of electrolytes namely: (a) Strong electrolytes  (b) Weak electrolytes Strong Electrolytes These are substances that completely dissociate into ions when dissolved in water, all...
Post a Comment
Read more

SSS 1: PARTICULATE NATURE OF MATTER (II)

-
Image
                Relative Atomic Mass The Relative Atomic Mass (RAM) of an element is the average mass of its atoms compared with one-twelfth (¹/₁₂) of the mass of one atom of carbon-12. The carbon-12 isotope (¹²C) is used as the standard for measuring atomic masses. Relative atomic mass of an element  = average mass of one atom of element     ¹/₁₂ × the mass one carbon -12 atom                     Relative Moleculer Mass Relative Molecular Mass ( RMM ), also called Molecular Weight, is the sum of the relative atomic masses (RAM) of all the atoms present in a molecule. The RMM has no unit (it’s a ratio). It shows how heavy a molecule is compared to ¹/₁₂  of the mass of one atom of carbon-12 (¹²C). Examples: 1. Water (H=1, O=16)  H₂O = (2 × H) + (1 × O)          = (2 × 1) + (16)          = 18 ...
Post a Comment
Read more