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Chapter 4 - elements, compounds and mixtures - Coggle Diagram

- - - - metallic and non-metallic properties
        
        metalloids (metalloids have metallic and non-metallic properties)
        
        high melting and boiling points
        
        brittle (easily broken when hammered)
        
        physical appearance: solids
        
        moderate heat conductivity
        
        shiny appearance (lustrous)
        
        moderate electrical conductivity
        
        non-metals
        
        low melting and boiling points (except for carbon and silicon)
        
        brittle if solid
        
        physical appearance: gases, volatile liquids or solids
        
        poor heat conductivity (except carbon in the form of graphite and diamond
        
        dull appearance (non-lustrous)
        
        poor electrical conductivity (except carbon in the form of graphite)
        
        metals
        
        shiny appearance (lustrous)
        
        physical appearance: mostly solids (except for mercury, liquid)
        
        high melting and boiling points (except for sodium, potassium and mercury)
        
        ductile (can be drawn into wires), malleable (can be hammered into different shapes without breaking) and sonorous (make a ringing sound when struck)
        
        good heat conductivity
        
        good electrical conductivity
      - physical states (at room temperature or pressure)
        
        e.g. gases, liquids or solids
  - - - atoms are the smallest particles of an element that have the chemical properties of that element
      - each element contains only 1 type of atom
      - noble gases such as helium, neon, argon, etc.are elements that exist as individual atoms. they are monatomic elements
    - - a molecule is a group of 2 or more atoms that are chemically combined (joined together)
      - monatomic = single atom
      - diatomic = 2 atoms (molecule)
      - polyatomic = 3 or more atoms (molecule)
      - all the atoms which make up the molecule, are made of the same element
      - e.g. a hydrogen molecule contains 2 hydrogen atoms that are chemically combined (it is diatomic). the symbol H2 is used to represent a hydrogen molecule. the subscript "2" after the chemical symbol for hydrogen indicates that 2 hydrogen atoms are chemically combined
- - - - e.g. sodium (element) and chlorine (element) react to form sodium chloride (compound)
  - - - e.g. in H2O, the "H" and "O" tells us that hydrogen and oxygen are present in the compound. while the subscript "2" tells us that the ratio of hydrogen to oxygen is 2:1.
  - - - thermal decomposition involves heating a compound strongly. e.g. when mercury(II) oxide is heated strongly, it decomposes to give the elements mercury and oxygen.
      - electrolysis is the process of using electricity to break down a compound.
- - - - the components of a mixture can be separated by physical processes such as magnetic separation, filtration or distillation. while a compound can only be broken down into its elements or into simpler compounds by chemical processes (e.g. thermal decomposition or electrolysis)
    - - the chemical properties of a mixture are the same as those of its components. while, the physical and chemical properties of a compound are different from those of its constituent elements.
    - - no chemical reaction takes place when a mixture is formed, usually there is little or no energy change. while, a chemical reaction takes place when a compound is formed, usually there is an energy change, e.g. the reactants get hot or cold.
    - - the components of a mixture can be mixed in any proportion, while the elements in a compound are always combined in a fixed proportion.