An ion is an atom that lost or gained one or more electron. A positive ion is an atom that lost an electron while a negative ion is an atom that gained an electron. Metals form positive ions while non-metals form negative ions. Monovalent Divalent Trivalent Hydrogen Sodium Potassium Floride Silver Chloride Bromide H+ Na+ K+ F+ Ag+ Cl- Br- Magnesium Calcium Barium Copper II Iron II Zinc Lead II Oxygen Sulphur Mg2+ Ca2+ Ba2+ Cu2+ Fe2+ Zn2+ Pb2+ O2- S2- Aluminium Iron III Nitrogen Al3+ Fe3+ N3- An atomic group is a group of atoms that are bonded together & go into chemical reactions as one atom. Atomic groups Formula Valency Hydroxide Nitrate Nitrite Bicarbonate Ammonium (OH)- (NO3) - (NO2) - (HCO 3) - (NH4) + 1 Carbonate Sulphate (CO3) 2- (SO4)2- 2 Phosphate (PO4)3- 3
2Na + Cl2 → 2NaCl This reaction involves gain & loss of electrons 2Na → 2Na+ + 2e- (loss of electrons is oxidation) Cl2 + 2e- → 2Cl- ( gains of electrons is reduction) An oxidation reduction reaction may also be defined as follows: Term Definition Oxidation Loss of electrons in a reaction. Reduction Gains of electrons in a reaction. Oxidizing factor The substance which gains electrons in a reaction. Reducing factor The substance which lost electrons in a reaction. Notes: The oxidizing agent is reduced in the reaction. The reducing agent is oxidized in the reaction. Oxidation & reduction are concurrent processes. (i.e. they occur together)
Solute molecules are distributed in the solvent in a regular way. You can’t distinguish the solute from the solvent by the naked eye. Examples: Sugar & water – salt & water - Metal alloys such as copper & silver used in making coins. The solute molecules are distributed in the solvent in an irregular way. The properties of the different layers of the mixture are different & can be Distinguish by the naked eye. Examples: Chalk & water – sand & water – oil & water The concentration of the solute in solution: Term Description 1- Unsaturated solution It can dissolve more solute; therefore you can dissolve more solute without change of temperature. 2- Saturated solution The maximum amount of solution is dissolved in a solution. 3- Super saturated solution By heating a Saturated solution, an additional amount of solute can be dissolved. Comparison points Colloidal Suspension Real solution Size of solute molecules medium large small
Distinguishing solute particles Distinguished by the microscope. Distinguished by the naked eye. Can’t be distinguished by Either the microscope or the naked eye. Components separation Its components cannot be separated by refining or filtration. Its components can be separated by refining or filtration. Its components cannot be separated by refining or filtration. Homogeneity Homogenous Non-homogenous Homogenous Examples Milk Chalk in water – sand in water Sugar in water – table salt in water Acids, bases & salt Acid Base Salt Definition When dissolved in water an acid contains positive hydrogen ions (proton H+). The aqueous solution of a base contains negative hydroxyl ions (OH-). It resulted from the reaction between an acid & a base. Effect on red litmus paper No change It changes red litmus paper to blue. No effect
Effect on blue litmus paper It changes blue litmus paper to red. No change No effect Examples Sulphuric acid hydrochloric acid, nitric acid & phosphoric acid Sodium hydroxide potassium hydroxide Sodium chloride magnesium chloride calcium sulphate potassium chloride Properties They have sour taste. They have soapy feeling. Reactions Acid + base salt + water The importance of common acids Acid Occurrence Importance Hydrochloric acid Stomach juice. Digestion of proteins in the stomach. Lactic acid Muscles. Produced during physical exercise. Sugar is processed quickly to give you energy & the product is lactic acid. Ascorbic acid= vitamin c Tomatoes & oranges. Needed for many functions in the body. Its deficiency causes illness. Folic acid Green leafy vegetable. Proper cell growth.
What’re radioactive elements? A radioactive element is an element with an unstable nucleus because the number of neutrons is higher than a certain number, therefore it radiates different radiations & gets converted to a stable element. Radioactivity occurs either naturally or artificially: Points of comparison Natural radioactivity Artificial radioactivity Definition It’s the radiation produced from radioactive element in nature. It’s the radiation released during nuclear reaction.
Lesson 1: The main principles of hereditary Introduction: What’s the reason for similarities of traits between family members? Genes are transferred from a generation to the next & the genes affect the traits of organisms. Key term; A trait is a distinct physical characteristic of an organism which is inherited ( got from the parents) or acquired ( determined by the environment ). Example; Eye color The color of the skin The number of fingers Blood groups The gene is heritable unit which is a portion of the chromosome.The gene influences the trait. The chromosome is a compact string of DNA. Mendel’s experiment: Gregor Mendel is the founder of heredity he conducted experiments on pea plants because : Pea plants are grown fast & easily. Their life cycle is short.