https___www.scribd.com_doc_96244755_10-1-the-Nucleus-of-an-Atom-Intensives.xml
http___fizika-osnove.blogspot.mk__1.xml
1.1 2.1 3.1 4.1 4.2 5.1 5.2 7.1 8.1 9.1 10.1 11.1 12.1 12.2 13.1 14.1 15.1 16.1 17.1 18.1 19.1 19.2 19.3 19.4 19.5 19.6 19.7 20.1 21.1 22.1 22.2 23.1 24.1 24.2 24.3 25.1 26.1 27.1 27.2 28.1 29.1 31.1 34.1 35.1 36.1 37.1 38.1 38.2 38.3 38.4 38.5 39.1 40.1 41.1 41.2 42.1 43.1 44.1 45.1 46.1 47.1 47.2 48.1 49.1 50.1 51.1 51.2 52.1 53.1 53.2 54.1
CHAPTER 10 10.1 UNDERSTAND THE NUCLEUS OF AN ATOM MENU Describe the composition of the nucleus of an atoms in terms of protons and neutrons. Define proton numbers and nucleon number. Explain the terms nuclide. Use the nuclide notation A Z MENU Define the term isotope. Describe the experiment to prove the atomic model NUCLEUS OF AN ATOM Matter is made up of very small particles called atoms Each atom has a very small and very dense core called nucleus. Most of the mass of atom is contained in the nucleus Structure of an Atom proton Nucleus Nucleus electron The positively charged mass within an atom, composed of neutrons and protons, and possessing most of the mass but occupying only a small fraction of the volume of the atom.// neutron • The electrons move in orbits around the nucleus. • There are a lot of empty space within atom • A nucleus consists of a number of proton and neutron. • Protons and neutrons also known as nuclide. • A proton has a positive charge. • A neutron is a neutral particle of about the same mass as the proton. • An atom is neutral because it contains an equal number of negatively charged electrons. So the net charge is zero. MENU Define proton number, Z • Proton number, Z, is defined as the number of protons in a nucleus. • The number of protons = the number of electrons • An element is identified by its proton number Define nucleon number (A) • Nucleon number, A is defined as the total number of protons and neutrons in a nucleus. It is also known as mass number. • Nucleon number, A = number of proton Z + number of neutrons MENU What is nuclide? • A nuclide is an atom of a particular structure. Each element has nucleus with a specific number of protons. MENU Nuclide Notation X Z Example • • • • A = nucleon number Z = proton number X = chemical symbol of the element Proton number of carbon = ___, Number of proton = _____ Number of electron = ___ Number of neutron = ______ MENU Define Isotope Isotopes are atoms with the same proton number but different nucleon number. • Isotopes of an element contain the same number of protons and the same number of electrons. So isotopes have the same chemical properties chemical reactions involve the electrons in an atom. • However they have different physical properties because their mass is different. • Some isotopes exist naturally. Isotopes can also be made artificially. MENU History of Rutherford Atomic Model Geiger and Marsden planned and carried out an experiment proposed by Sir Ernest Rutherford and found evidence for Rutherford Model. They fired a stream of alpha particles at a very thin gold foil and counted how many alpha particles were scattered at a number of different angles. Geiger and Marsden experiment The result and the conclusion of the experiment is simplified in the table below: Result Most of the alpha particles passed straight through the foil in their original direction. Conclusion Most of the space taken up by an atom must be completely empty. A very small nucleus is placed at the centre of the atom. The result and the conclusion of the experiment is simplified in the table below: Result Conclusion A few alphas particles were deflected through very small angles The nucleus are positively charged. The alpha particles also positively charged are repelled by the nucleus because repulsion force is produced between the like electric charges. The result and the conclusion of the experiment is simplified in the table below: Result A very small number of alpha particles were bounced back by the gold foil. Conclusion The alpha particles collides head on with the nucleus MENU
1.1 2.1 2.2 2.3 2.4 2.5 3.1 4.1 4.2 5.1 5.2 5.3 6.1 7.1 7.2 7.3 8.1 9.1 10.1 10.2 10.3 11.1 11.2 11.3 12.1 12.2 13.1 13.2 13.3 14.1 15.1 16.1 16.2 16.3 17.1 17.2 17.3 18.1 18.2 18.3 19.1 19.2 20.1
Građa atoma Atom je osnovna gradivna jedinica svakog tijela. Znači sve se sastoji od različitih vrsta atoma, od metala preko živih bića do vode i zraka. Postoji li negdje gdje nema atoma? Jedino vakum. Znači u prirodnim uvjetima na Zemlji svugdje ima atoma! Atom je najlakše predočiti kao Sunčani sustav. Atom se pak sastoji od dva osnovna „dijela“ : jezgra (koju zamišljamo kao Sunce) i elektronski omotač (njega predočujemo kao planete koji se vrte oko Sunca). U jezgri se nalaze protoni i neutroni, dok se u elektronskom omotaču nalaze elektroni. Čestice: - protoni su pozitivno nabijene čestice. Svaki proton je jedan +. Označavamo ga p+. - - neutroni su neutralne čestice. označavamo ga s n0. - - elektroni su negativno nabijene čestice. Svaki eletron je jedan -. Označavamo ga e-. Atom je prema van neutralno nabijen što znači da ima isti broj elektrona i protona. Svaki atom ima dva broja koja ga označavaju: Relativna atomski masa – označava se s „A“ to je prosječna težina atoma. Težinu čini zbroj protona i neutrona, elektroni su zanemarivo laki. Uglavnom ima decimale jer u istoj vrsti atoma postoje odstupanja u broju neutrona pa se uzima prosječna težina. Atomski broj ili protonksi broj – označava se s „Z“. Ujedno označava broj i protona i elektrona jer elektrona ima isti broj kao i protona. Uvijek je cijeli broj. Valentnost atoma je svojstvo nekog atoma da se spaja s određenim brojem drugih atoma. Ako je atom jednovalentan onda se može spojiti samo s jednim atomom. Elektronksi omotač ima ima svoje orbitale koje se popunjavaju određenim redoslijedom. Ima sveukupno 7 orbitala (K, L, M, N, O, P, Q,). One su bitne jer zadnja popunjava (odnosno polupopunjena orbitala) određuje valentnost atoma. PES (periodni sustav elemenata) Vrlo složen i dobro osmišljen sustav u kojem se nalaze kemijski elementi. Sada ću objasniti samo najosnovnije. Njime se valja pozabaviti više u posebnom tekstu samo o njemu. Sastoji se od 7 perioda i 18 grupa. Periode su kao što vidite vodoravne, a grupe vertikalne. Slova označavaju kemijski element – prvo slovo je veliko drugo malo, gore lijevo iznad slova se nalazi atomski broj, dok gore desno piše relativna atomska masa. Ovo je najjednostavniji PES. PES može biti puno složeniji s obzirom kome je namjenjen. Na PES mogu se nalaziti jos mnogi podaci, npr: godina otkrića, vrelište, talište, elektronska konfiguracija, oksidacijski brojevi, baznost, kiselost itd. Kemijski elementi su poredani po atomskom broju kao sto možete vidjeti, on raste s lijeva na desno. Grupirani su metali, nemetali, plinovi, plemeniti plinovi… Više o PES u zasebnom tekstu.