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The Charge of Particles A neutral atom contains the same number of electrons as the protons. The positive and negative charges of the protons and electrons respectively neutralise each other, for example, (+4) + (-4) = 0 If the number of protons is greater than the number of electrons, the particle is positively charged. If … Read more
Modern Atomic Model According to the modern atomic model, The central nucleus consists of protons and neutrons. It containing almost all the mass of the atom. the nucleus of an atom is very small compared to the size of the atom the electrons are orbiting outside the nucleus in the electron shells the electrons are … Read more
History of Development of the Model of Atom Table below shows the scientists that contribute to the development of the Model of Atom. John Dalton Five main points of Dalton’s Atomic Theory All matter is composed of extremely small particles called atoms. All atoms of a given element are identical, having the same size, mass, … Read more
Melting Point, Boiling Point and State of Matter The physical state of a substance at a certain temperature and pressure depends on the values of its melting and boiling points. A substance is in solid state if it exists at a temperature below its melting point. A substance is in liquid state if it exists … Read more
Cooling Curve The graph above shows the cooling curve of a substance. P P-Q Q Q-R R R-S S S-T T T-U U P The substance exists in gaseous state. The particles have very high energy and are moving randomly. The intermolecular forces between the particles are very weak and can be ignored. P-Q The … Read more
Heating Curve A A-B B B-C C C-D D D-E E E-F A Naphthalene is in solid state at any temperature below its melting point. The particles are very closely packed together in an orderly manner. The forces between the particles are very strong. The particles can only vibrate at a fixed position. A-B As … Read more
Inter-conversion between States of Matter Change in Heat and Kinetic Energy of Particles The change in temperature will influences the kinetic energy or the speed of the motion of the particles. When a substance is heated, the kinetic energy of the particles in the substance increases. This causes the particles to move or vibrate faster. … Read more
Matter exists in 3 states of matter, namely, solid state, liquid state and gaseous state. Characteristics of Matter in Solid, Liquid and Gaseous State Arrangement of Particles Solid Particles are arranged in an orderly manner and close to one another. Liquid Particles are not arranged in order. The space between particles is moderately large. Gas The … Read more
Element and Compounds Matter can be divided into elements and compounds. Elements An element is a substance that consists of only one type of atom. Element can be either atoms or molecules. Example: (Both the iron and oxygen are element because they consist of only one type of atoms) Compounds A compound is a substance … Read more
Symbol of Elements A symbol of element is the chemical symbol written in short form to represent a particular element. Some elements are represented by the first letter of its name. Examples: Element Symbol Fluorine F Hydrogen H Iodine I Nitrogen N Oxygen O Phosphorus P Sulphur S Carbon C Vanadium V If there are two … Read more