Chemistry

Define Electrodes,  Anode,  Cathode,  Cations & Anions. Electrodes: These are rods (plates) made up of graphite or metals through which current enters or leave.   Anode: The positive electrode is called Anode. Cathode: The negitive electrode is called Cathode. Moving charges: There are 2 charges, positive & negative Negative charge moves towards positive terminal (electrode) Metals donate electrons forming positive ions For example:         Na + ,     K + ,       Ca 2+ ,      Al 3+ Exceptional case     H +     &     NH + 4 Non-metals accept electrons forming negative ions For example:            Cl - ,     Br - ,      I - ,      O ...

Define Giant covalent structures. Giant covalent structures: The great variety of life on Earth depends on carbon's ability to form covalent bonds with itself. As the element, carbon atoms can bond to millions of other carbon atoms in both diamond and graphite. The atoms are arranged in a giant covalent structure. Some people call this a giant molecular or macromolecular structure. Another substance with a giant covalent structure  is silica. Its chemical name is silicon dioxide (SiO2). It melts at over 1500 °C. Substances with giant covalent structures are not soluble in water. Their particles are not charged (unlike ionic compounds). Water molecules are not attracted to them. They don't conduct electricity in any state. There are no free ions or electrons to carry the charge.                                 ...

Unit 3  Lesson 4: Arab Republics Lesson Objectives: 1) identify Egypt and Syria as Arab republics 2) identify some characteristics of those countries and their leaders Some Arab countries are republics. A president rules them with a parliament (group of representatives elected by the people of the country). Egypt is one of the biggest republics in the Arab world. It has a very interesting history that has attracted many people over the years.   Year Important Historical Event 3100 B.C.  (Before the birth of Jesus) King Menes of Upper Egypt conquered Lower Egypt and formed his empire. (Ancient Egypt was divided into two parts: Upper Egypt (to the south), Lower Egypt (to the north). This division is related to the flow of the Nile river from Eastern Africa going north to the Mediterranean Sea. So Upper Egypt is to the south of Lower Egypt, and Lower Egypt is mainly the Nile Delta). 2700/2200 B...

What is  Electrolysis,  Electrolyte and  Electrolytic cell? Electrolysis: “Decomposition of a compound by passing electricity through is called Electrolysis”. Electrolyte: A compound that does not conduct electricity in solid form but it only conducts in molten or solution form is called Electrolyte.   Electrolytic cell: It is a device that uses electrical energy to start a chemical reaction. Electrolysis is the break down of a compound by electricity. Electrolytes are liquids (molten compounds or compounds in solution) which are broken down when they conduct electricity. Why electrolytes conduct?   Electrolytes contain ions. Electrolytes need electricity to pass. Ions carry charge. Ions are not free to move (bound in solid form). So electrolytes needs to be in molten form or soaked in water.                  ...

Define the following terms: i)   Electrolysis ii)   Electrolyte iii) Electrolytic cell iv) Electrodes v) Anode vi) Cathode vii) Redox Reaction viii) Oxidation ix) Reduction X) Ionic half equations   Electrolysis: “Decomposition of a compound by passing electricity through is called Electrolysis”. Electrolysis is the break down of a compound by electricity. Electrolyte: A compound that does not conduct electricity in solid form but it only conducts in molten or solution form is called Electrolyte.   Electrolytic cell: It is a device that uses electrical energy to start a chemical reaction. Electrodes: These are rods (plates) made up of graphite or metals through which current enters or leave.   Anode: The positive electrode is called Anode. Cathode: The negative electrode is called Cathode. Redox reaction: A reaction that involves both oxidation and reduction-reaction is called redox reaction.   Oxidatio...

What are Extinct Species,  Endangered species and  Threatened species ? Extinct Species: Extinction is the termination of a kind of organism. The disappearance of  species  from Earth. When the last member of a species dies, the species becomes an extinct species.  A  species  not definitely located in the wild  Endangered species: When a specie in danger of becoming extinct, it is called an endangered species.  A species that is very likely to become extinct in the near future. Threatened species: Species with low numbers that could become endangered are called threatened species.