ساينس الصف الأول الاعدادي – الفصل الدراسي الاول ساينس اولي اعدادي ترم اول In This part we will study : 2. Electrons [ Location ] They orbit (revolve around) the nucleus at very high speed. [ Charge ] They are negatively (-ve) charged particles. [ Mass ] The electron has a negligible mass relative to that of the proton or neutron. [ Number ] The number of negative electrons which revolve around the nucleus is equal to the number of positive protons in the nucleus, so the atom is electrically neutral in its ordinary state. From all the previous explanation, we conclude that: • Atomic no.= no. of protons= no. of electrons • Mass no. = no. of protons (atomic no.) + no. of neutrons :. Number of neutrons= mass number – atomic number (G.R) The mass number is always larger than the atomic number. Because the mass number equals the sum of the numbers of protons and neutrons in the nucleus, but the atomic number equals the number of protons only. 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