Atomic Structure Knowledge Organiser PDF

Chemistry Knowledge Plum pudding Organiser model JJ Thompson discovered the electron – negatively charged particles which were smaller than atoms which. Atomic structure (Tri...

Chemistry Knowledge Plum pudding Organiser model JJ Thompson discovered the electron – negatively charged particles which were smaller than atoms which. Atomic structure (Triple Changing ideas about atoms Science) Daltons model was adapted to give the plum pudding model. This said an atom is a ball of positive charge with negative electrons embedded in it. Rutherford scattering Ernest Rutherford fired alpha particles at a thin sheet of gold atoms. Early ideas about atoms John Dalton described atoms as solid spheres of matter, rather like a snooker ball that could not be Evidence Conclusion divided into anything smaller. Most alpha particles Most of the atom is empty passed straight through space and the mass is concentrated in the centre Some particles were Atom has a positively scattered charged nucleus  Chemistry Knowledge Modern structure of the atom Organiser The radius of an atom is about 1x10-10 m (0.1 nm). Atomic structure (Triple The radius of the nucleus is about The nuclear model Science) 10 000 smaller than the atom. In the nuclear model developed by Rutherford atoms were: Mostly empty space Mass Charge Mass concentrated in nucleus Proton 1 +1 Positive charge in nucleus Electrons separated from Neutron 1 0 nucleus Electron 0 -1 Bohr model Atoms have no overall charge as they have the same Electrons orbit the nucleus number of positive protons as neutral electrons. At specific distances from the nucleus, in electron shells Electron configuration Fill innermost shell first. Maximum numbers of Chadwick & the neutron electrons: In 1932 Chadwick discovered Shell 1: 2 electrons the neutron Shell 2: 8 electrons Because it had no charge it Shell 3: 18 electrons was difficult to discover and so was discovered later than the proton and electron Example: Potassium Potassium has an electron configuration of 2.8.8.1 When filling shell 3, 8 electrons go into it before 2 electrons then go into shell 4, then the remaining 10 electrons go into shell 3.  Chemistry Knowledge Calculating relative atomic Organiser mass (Ar) Atomic structure (Triple Atomic Science) number & mass Ar = (39 x 93.3) + (41 x 6.7) number 100 F Mass number = protons + neutrons 19 Ar = 39.134 Proton number = protons 9 Number of neutrons = mass number – proton number For atoms: number of electrons = number of protons 19 F would have 19 – 9 = 10 neutrons Isotopes Isotopes have same numbers of protons - they are the same element Isotopes have different numbers of neutrons – different mass numbers Isotopes have identical chemical properties – same electron structure