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C1 Atomic structure, C3 Structure and bonding, C5 Chemical changes, C4…

- - - - the inner ring represents the 1st shel. it can hold up to 2 electrons
      - the 2nd shell can hold up to 8 electrons
      - the 3rd shell can hold up to 8 electrons and when it is full the 4th shell will begin to fill
      - the number of electrons in the outermost shell of an atom corresponds to its group in the periodic table
- - - - lists all chemical elements
      - It has eight main groups. All the elements in each group have similar properties.
    - - The atom has a nucleus in the centre. it is made up of neutrons and protons.
      - electrons orbit around the nucleus in shells
  - - - atoms that gain electrons become negative ions and if atoms lose electrons they become positive ions
        
        study tip: if atoms lose electrons they are giving away which is a positive thing to do. If an atom gains an electron they are stealing from somewhere else which is a negative thing to do.
      - atomic mass is always on the top when representing an atom and its qualities and the atomic number is underneath
      - an isotope is an atom with a different number of neutrons. they have identical chemical properties but there can be a difference in the physical qualities such as density
- - - - C2.2 Electronic structures and the periodic table
        
        The atomic number (proton number) of an element determines its position in the periodic table
        
        the number of electrons in the outer most shell corresponds with its group in the periodic table which also determines its chemical properties
        
        the atoms of metals usually lose electrons where as non metals usually gain electrons
        
        The Noble gasses in group 0 are unreactive because they have very stable electron arrangements
      - C2.3 Group 1 - the alkali metals
        
        group 1
        
        they are called the alkali metals
        
        when going down the rows on the periodic table the melting and boiling points decrease
        
        all of these elements react with water and produce hydrogen and an alkaline solution with metal oxide
        
        in a reaction to make ionic compounds they all form positive ions with a +1 charge. their compounds are usually white or colourless crystals that dissolve in water which produce colourless solution
        
        the reactivity of the 'alkali metals' increases going down the group
      - C2.4 Group 7 - the halogens
        
        Group 7
        
        they are called the hallogens
        
        the halogens all form a -1 charge in their ionic compounds with metals
        
        the halogens form covalent compounds by reacting with other non metals
        
        A more reactive halogen can displace a less reactive halogen from a solution of one of its salts
        
        the reactivity of the halogens decrease going down the group
      - C2.5 Explaining trends
        
        you can explain trends in reactivity as you go down a group in terms of the attraction between electrons (in the outermost shell) and the neucleus
        
        this electrostatic attraction depends on:
        
        the distance between the outer most electrons and the neucleus
        
        the number of clompleted shells
        
        the size of the positive charge on the neucleus (called the neucleus charge)
        
        taking all these factors into consideration it means that it is easier for larger atoms to lose atoms than them to gain electrons and it is easier for a small atom to gain electrons than them to lose electrons
      - C2.6 the transition elements
        
        compared with the alkali metals, transition elements have much higher melting points points and densities. they are also stronger and harder, but are much less reactive
        
        the transition elements do not react vigourously with water or oxygen
        
        a transition element can form both positive ions and negative ions
        
        transition elements and their compounds are important industrial catalysts
      - C2.1 development of the periodic table
        
        mendaleev's periodic table left gaps for any elements that might be discovered in the future. this is one of the reasons why his table was accepted by the scientific community
        
        the periodic table was developed by chemists that tried to classify the elements. it arranges them in the order which elements with similar properties will be grouped together
- - - - how easy it is to extract the metal from its ore
      - how much metal the ore contains
      - changing demand for the metal