ساينس الصف الأول الاعدادي – الفصل الدراسي الاول ساينس اولي اعدادي ترم اول In This part we will study : The atomic construction the atom consists of : Nucleus. Electrons. 1. Nucleus [ Location ] It is the central core of the atom. [ Charge ] It is positively charged, because it contains : • Protons : positively (+ve) charged particles. • Neutrons : electrically neutral (±ve) particles (uncharged). [ Mass ] The mass of the atom is concentrated in the nucleus. (G.R) because the electron has a negligible mass relative to that of the proton or neutron. Mass number • It is the sum of the numbers of protons and neutrons in the nucleus of an atom. • It is written above the symbol on the left side. Atomic number • It is the number of protons in the nucleus of an atom. • It is written below the symbol on the left side. 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