ساينس الصف الثاني الاعدادي – الفصل الدراسي الاول ساينس تانية اعدادي – ترم اول In This part we will study : The graduation of some properties of the elements in periods and groups (A). Such as : 1. Atomic size . 2. Electronegativity. 3. Metallic and non-metallic properties . 1. Atomic size – The atomic size is determined by knowing the atomic radius of the atom and its measuring unit is picometre (Pm). – Picometre = part of million of the million part of a meter. Graduation of atomic size of elements in the periodic table : Atomic size in periods Atomic size in groups Note : • Nucleus is positively charged because it contains protons (positively charged) and neutral neutrons . • The largest atom of elements in size is cesium (Cs) atom and the smallest one is fluorine (F ) atom . لمتابعة مستر احمد الباشا وكل ما يخص الساينس : جروب الفيس بوك http://bit.ly/2Of1mcN صفحة الفيس بوك http://bit.ly/2Gq5xMo بالتوفيق مستر احمد الباشا