Category Archives: 1.1 Fundamental ideas

Valence electrons and octet rule

  Key Chemistry Concept: Chemical reactions occur by atoms transferring or sharing electrons with each other. However, ONLY the electrons that occupy the outermost shell of atoms are involved in electron transfer or electron sharing between atoms.The electrons that orbit closer to the nucleus are, by definition, not in the outermost shell, and are therefore (usually) unaffected during chemical reactions. Valence number The

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What are the relationships between atom, element, molecule, ion, compound and mixture?

What are the relationships between atom, element, molecule, ion, compound and mixture? Matter is made up of repeating units of atoms, molecules or ions. An element is a substance that contains only one type of atom as its repeating unit. A monatomic element has a single atom (e.g. copper, sodium or helium) repeating unit. Whereas, a polyatomic element, has a multiple atom

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C1.1 Atom ‘dot’ electron(s) and nucleus diagrams

Electrons occupy particular energy levels Each electron in an atom is at a particular energy level (in a particular shell). 1st shell (the ‘innermost’) shell can occupy a maximum of 2 electrons 2nd shell (‘outside the first shell’) can occupy a maximum of 8 electrons 3rd shell (‘outside the second shell’) can occupy a maximum of 8 electrons At GCSE level, because

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C1. 1 The Periodic Table

Periodic Table This is a table-like chart that shows all the elements with their corresponding symbols- there are just over 100 different elements! The horizontal rows in the periodic table are called periods and the vertical columns are called groups. The Periodic Table has 8 Groups: starting from the left is Group 1, then Group 2… Group 8 is also

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C1.1 Atoms

The difference between atoms, elements, compounds, mixtures and ions always confuses students. Further information may be found here. Atom All substances are made of tiny particles called atoms. Atoms have a small central nucleus, which is made up of protons and neutrons and around which there are electrons. Element A substance that is made of only one sort of atom

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