أرشيف الوسم : energy

Electron affinity It is the amount of energy given out when an electron is added to a neutral gaseous atom. This results in the formation of an anion. For example Cl + e– → Cl + energy. The electron affinity of chlorine is 348 kJ mol-1. Electron affinity changes across a period. The electron affinity of the atoms increases from …

Ionization energy (or potential) of an element is defined as “The amount of energy required or needed to remove an electron from the neutral gaseous atom to form unipositive ion , for example Na → Na+ + e– + energy This is measured in electron volts per atom or kJ mol-1. For example IE of Na is 495 kJ mol-1. …

Quantization: means that a quantity does not vary continuously. The energy of an electron in an atom cannot have any arbitrary value but only certain characteristic values. ­A definite quantum of energy is accepted while moving from lower to higher energy level or lost while moving from higher to lower energy level, It does not accept any amount of energy …

A technique for cooling a paramagnetic salt, such as potassium chrome alum, to a temperature near absolute zero. The salt is placed between the poles of an electromagnet and the heat produced during magnetization is re­moved by liquid helium. The salt is then isolated thermally from the sur­roundings and the field is switched off; the salt is demagnetized adiabati­cally and …

Internal energy: The energy stored in a fixed amount of a substance (atom or molecule) is known as its internal energy. It is denoted by the sign E. Change in internal energy: It is the difference in the internal energies of the product and the reactant species taking part in a chemical reaction at constant volume. It is denoted by …

Dalton’s Model of the atom. It is the basis of our understanding of the nature of matter. The following four statements comprise Dalton’s Model: a –  All matter is made up of extremely tiny. particles. called atoms. b-  Atoms are indivisible. c – Atoms of the same element are alike. d –  Atoms of different elements are different. e – …

Like matter, energy can be classified in different ways. For example, energy can either be kinetic or potential. Kinetic energy is energy of motion. Gases are made of molecules that have more kinetic energy than molecules in the solid phase of that substance. For example, water molecules in steam have greater kinetic energy than molecules in liquid water. Potential energy …

طاقة كيميائية chemical energy : تسمى الطاقة المحتجزة في الروابط التساهمية بين الذرات باسم الطاقة الكيميائية . كل رابطة لها مقدار معين من الطاقة . في حالة كسر الرابطة فإن يتطلب ذلك وجود طاقة للقيام بذلك و يسمى هذا النوع من التفاعلات باسم  تفاعل ماص للحرارة ، أما عندما ترتبط الروابط المكسرة مع بعضها البعض مرة ثانية لتكون جزيئات جديدة …