Keyword Definition Dmitri Mendeleev arranged the known elements (only ~60 were known to exist at the time) in order of increasing relative atomic mass.He then arranged the elements a substance that cannot be broken down into any other Element similar properties into groups. Mendeleev later made a few changes to his order: substance. He left gaps for elements yet to be discovered He switched the order of a few elements to keep the properties of the Atom the smallest particle of a chemical element that can exist. groups consistent By looking at the chemical and physical properties of the elements next to a gap, he Periodic table A chart showing all of the elements predicted the properties of these undiscovered elements. Later, properties of new elements were found to be similar to the predicted ones Vertical column on the periodic table and confirmed Mendeleev's periodic table. group Periodic table now Mendeleev version Year 7: Autumn Term Year Period Horizontal row on the periodic table Electron Shows how the electrons are arranged configuration Key facts Atoms are made up of protons, neutrons and electrons Atoms are neutral as they have the same number of positive protons and negative electrons Atom structure Electrons are found in shells. Each shell can only hold a certain number of electrons. GROUP NUMBER = NUMBER OF ELECTRONS ON THE OUTER SHELL SCIENCE: SCIENCE: MendeleviumandRutherfordium PERIOD = NUMBER OF SHELLS THAT HAVE ELECTRONS IN An element symbol is one or two letters. The first is ALWAYS a capital and the second (if there) is ALWAYS lowercase Protons + neutrons You can work out how many protons, neutrons and electrons an atom has using information from the periodic table Electrons are arranged in shells, Protons filling from the inside->outside Quickfire questions Commonly misspelt words: 1. What is an atom made up from? 2. Where are the protons located in an atom? Nucleus 3. Where are the neutrons located in an atom? Neutron 4. Where are the electrons located in an atom? Neutral 5. What is the charge of a proton? 6. What is the charge of an electron? Draw a fully labelled atom of carbon 7. What is the charge of a neutron? 8. Why are atoms neutral 9. How many protons, neutrons and electrons does an atom of lithium Year 7: Autumn Term Year have? 10. What is the electron configuration of sodium? Describe an atom of sodium in detail. How many protons, neutrons and electrons doe the atom have? Where are they located? At home: Make a model of an atom – it could be like the ones below SCIENCE: SCIENCE: MendeleviumandRutherfordium Useful links: https://www.bbc.co.uk/bitesize/clips/zbv2hyc https://www.bbc.co.uk/bitesize/guides/zt2hpv4/revision/1.