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Nucleus development Charge This experiment allowed Rutherford to replace the plum pudding -1 0 model with the nuclear model – the Proton +1 1 was mainly empty space with a small positively charged nucleus 0 1 Element All the same type of atom

Alpha particle scattering Geiger and Key words: Marsden 1. Proton: Found inside the nucleus of an atom, have a positive charge Compound fired positively-charged alpha More than one type 2. Electron: Found in rings orbiting the nucleus, have a negative charge at gold foil. This showed of atom chemically that the mas of an atom was 3. : Found in the nucleus of an atom, have no charge bonded together concentrated in the centre, it was 4. Nucleus: The centre of an atom, made up of protons and neutrons positively charged too 5. : The mass of the atom, made up of protons and neutrons Mixture Plum pudding 6. : The number of protons in an atom More than one type After the electron 7. Element: All the same type of atom chemically bonded together of element or was discovered, 8. Compound: More than one type of atom chemically bonded together compound not chemically bound Thomson created the 9. Mixture: More than one type of element or compound not chemically together plum pudding model – bound together the atom was a ball of 10. Electron Shell: A ring surrounding the nucleus containing the positive charge with negative electrons scattered in it

Position in the Periodic Rules for electron shells: Table: 1. The first shell will only hold Rules: 1. The number of 2 electrons 1. Mass number = protons + neutrons electrons in the outer 2. Shells after the first one 2. Atomic number = no. of protons shell tells us the group will have up to 8 electrons Early 3. No. of electrons = no. of protons ideas in the 3. Electrons try to move as Before the 2. Potassium 2,8,8,1 and far away from each other K discovery of 2,1 both have 1 as possible : the electron, electron in their outer 4. Once the 4 points are filled 2,8,8,1 thought shell and are both up then the electron's will found in group 1 pair up 1. Mass number = protons – neutrons that 7 = 3 + neutrons 5. We write the electron Mass number = 39 were tiny 7 – 3 = neutrons = 4 Atomic number = 19 spheres, that configuration, which tells us 2. Atomic number = no. of protons Protons = 19 Protons = 3 couldn’t be how many electrons are in Electrons = 19 each shell 3. no. of electrons = no. of protons Neutrons = 4 divided Electrons = 3 Development of the periodic table As more elements were discovered scientist Mendeleev tried to classify them Overcame the problems of atomic weight. He Early tables did this by; • First attempts to • Leaving gaps classify elements were • Changing the order of made before subatomic the elements particles were discovered • Predicted elements • John Newlands ordered were discovered the elements based on • Differences were atomic weight accounted for by • Wrong groups used

Keywords: 1. Atomic Number: number of protons (which is equal to number of electrons) in an atom 2. Number: number of protons + neutrons in the nucleus Today of an atom • Elements with similar 3. : atoms that have the same number of protons and electrons properties arranged in groups but a different number of neutrons • 4. : An atom that has gained an electron is a negative ion (non-metal) Based on properties and atom that has lost an electron is a positive ion (metal) • All have the same number of 5. Group: column number in periodic table representing number of electrons in the outer shell electrons on outer shell • The arrangement of elements in Metals a table based on proton number, • Majority of elements are 6. : row number in periodic table representing number of electron properties and outer electron metals shells • Form positive number • Found on left hand side, Isotopes middle and bottom of table Same number of protons and electrons, Group 7 • Non-metals but a different number Halogens • Form of neutrons. • 7 outer electrons negative ions The overall charge • Non-metals • Found on stays the say because • made of pairs of right hand neutrons are neutral atoms Group 1 side and top • React with metals to form • Alkali metals of table ionic compounds • 1 outer electron • React with non-metals to • Reactivity increases form covalent going down the group compounds Questions 1. Draw and label the structure of an atom 2. Describe the differences between an atom, element and a compound 3. Name the 3 key parts in a word equation 4. How was the periodic table first ordered? 5. Why were early versions of the periodic table changed? 6. Describe 2 changes Mendeleev made to the periodic table 7. Describe one similarity and one difference between Mendeleev’s and Newlands’ periodic table 8. Why are the groups in the periodic table so useful? 9. How are the elements arranged in the modern periodic table? 14. Draw the electron structure for sodium, lithium and potassium 15. What is the electron structure for the alkali metals? 16. Describe the trend of reactivity in the alkali metals 17. Describe the properties of group 7 elements

18. Draw the electron structure for fluorine, and bromine 19. Describe the difference in formation of ions between metals and non-metals 21. Describe the mass, charge and location of the subatomic particles 22. Draw the electron structure for the first 12 elements in the periodic table 23. Describe 3 key differences between the plum pudding model and the nuclear model 24. Describe 2 similarities between the plum pudding model and the nuclear model 25. Explain how Geiger and Marsden’s experiment led to the discovery of the nucleus