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C1 key concepts in chemistry, c1 (the periodic table) - Coggle Diagram

- - - - FE - iron, O,CO - cobalt
  - - - compounds are broken up or formed
      - at least one new substance is created
      - measurable energy change
      - No atoms are created not destroyed
- - - - daltons model
        
        in 1803, john dalton first suggested that all matter is made up of atoms and that attoms cannot be split, scientists improved daltons original model of an atom with the discovery of sub atomic particles
      - thomsons plum pudding model
        
        in 1897 a english physiscist called jj thomson dicovered lectrons
        
        He modelled the atom as a plum pudding - a ball of positive charge with negatve electrons mixed in
    - - In 1909 ernest rutherford discovred that particles could bounce back off atoms
      - He concluded that an atom's mass is concentrated in the atom's centre. This was called the "nucleus" and it contained positively charged particles called protons.
    - - Niels bohr discovered that electrons orbit the nucleus at fixed distances
      - In 1932, James Chadwick discovered that some particles in the nucleus have no charge at all. He called them neutrons.
  - - - protons have a relative charge of 1
      - protons have a relative mass of 1
    - - electrons have a relative charge of -1
      - relative mass - 1/1836
      - fixed in orbits around the nucleus
    - - relative charge of 0
      - relative mass of 1
  - - - atoms are tiny and very light They are made up of sub-atomic particles (protons, neutrons, and electrons), which are even smaller and lighter than an atom.
      - how big are atoms
        
        the radius of atos is approx 0.1 nanometres
        
        the nucleus of an atom is 10* smaller than the atom. Most of an atoms mass is concentrated in the nucleus
    - - The atomic number
        
        number of protons in the atom
      - mass number
        
        the mass number of an atom is calculated by adding together the num of protons and neutrons
      - exam question
        
        Can you remember the 2 analogies that helped show how small atoms and sub-atomic particles are?
        
        Size of atoms.
        About 5 million hydrogen atoms could fit into a single pin head.
        
        Size of sub-atomic particles.
        The nucleus of an atom is 10,000 times smaller than the atom itself. So, if the atom was the size of Wembley Stadium, the nucleus would be the size of a garden pea.
  - - - these are known as isotopes
        
        hydrogen has 3 isotopes
        
        Protium - protium is a hydrogen atom which contains 1 proton and 0 neutrons
        
        99.98% of hydrogen atoms are protium
        
        It is used in hydrogen fuel cells and the production of plastics.
        
        Deuterium
        
        Deuterium is a hydrogen atom with one proton and one neutron
        
        around 0.02 of hydrogen atoms are Deuterium
        
        it is used in nuclear fusion
        
        Tritium
        
        Tritium is a hydrogen atom with 1 proton and two neutrons
        
        it is very rare
        
        it is used in thermonuclear fusion weapons
    - - a nuclide is a type of isotope
      - a nuclide refers to a specific nucleus that creates a certain number protons and neutrons
    - - the relative atomic mass is the average mass of all the isotopes of an element , it takes into account how often each isotope is found
- - - - this means theyll react in similar ways
  - - - newlands perodic table
        
        jon newlands was the first chemist to devise a periodic table
        
        his periodic table was ordered by the weight of the element
        
        however the table was incomplete and some elements were placed in inappropriate groups
      - mendeleevs periodic table 1869
        
        dimitri mendeleev realised that there were many undiscovrerd elements
        
        he added gaps to newlands table to account for undiscovered elements
        
        he even predicted the mass and properties of these undiscovered elements
      - modern periodic table
        
        the discovery of protons and isotopes has shown that mendeleev had ordered elements exactoly by atomic number
  - - - metals are found on the left of the periodic table because they have few electrons in their outer shell
      - when metaks react they lose one or more of these electrons to form positively charged ions
      - properties of metals
        
        high melting and boiling points
        
        good conductors of heat and electricity
        
        theyre all solids
    - - non metals are found on the right of the periodic table because they have many electrons in their outer shell
      - when non metals react , they either gain electrons to form negative charged ions or share to form neutral molecules
      - properties of non metals
        
        lower melting and boiling points
        
        often found as gases
        
        generally dont conduct heat or electricity
- - - - when an atom gains or loses electrons, the nucleus does not change this means atomic mass and atomic number stays the same
  - - - Molecules are groups of two or more atoms joined together by chemical bonds. Simple molecules are formed when two or more atoms join together by covalent bond.
      - properties of simple covalent compounds
        
        low melting and low boiling points
        
        the reason why they have low melting and boiling points is because of their weak intermolecular bonds , when the substance melts or boils these intermollecular are easily overcome and broken down
        
        substances that consist of simple molecules are non conductor of electricity because the substances do not have an overall electric charge or free electron
    - - when atoms share pairs of electrons they form strong covalent bonds, macromolecules contain alot of non metal atoms each joined to adgacent atoms by covalent bonds
      - Macromolecules have very high melting points, because a lot of strong covalent bonds must be broken.
      - examples of macromolecules
        
        diamond , graphite, silica
        
        diamond
        
        diamond is a form of carbon in which each carbon atom is joined to four other carbon atoms through covalent bonds, forming a giant covalent structure
        
        due to this bonding, diamond is very hard and has a high melting point, it also does not conduct electricity
        
        graphite
        
        graphite is a form of carbon in which each carbon atom bonds to three other carbon atoms, forming layers
        
        layers can slide over eachotherbecause theres no covalent bonds between the layers
        
        makes graphite soft and slippery
        
        cos each carbon atom is joined to three other carbon atoms, means the fourth electron in outermost shell is free and is found above and below the plane of layers
        
        these electrons are called delocalised electrons as they are held loosely to the carbon atoms and can drift along the layers in graphite
        
        silica
        
        silica or silicone dioxide is found in sand
        
        it has a similar structure to diamond where each silicone atom is joined to four oxygen atoms
        
        It is also hard and has a high melting point
        
        properties of giant covalent structures
        
        very high melting points
        
        because alot of strong covalent bonds have to be broken
        
        1 more item...
        
        variable conductivity
        
        diamond doesnt conduct elect while graphite does because it has free electrons silicone is semi condcutive The fact that it is a semi-conductor makes it useful in the electronics industry as most transistors are made of silica.
  - - - number of elect = to number of neutrons
      - Ions have the electronic structure of a noble gas i.e. full outer shells.
      - The oppositely charged ions attract and are arranged by electrostatic attraction in a way to form giant ionic crystal lattices. The ions in a crystal lattice are very strongly bonded, and a high temperature is required to melt the crystal.
  - - - high melting and boiling points
        
        ions in crystal lattice strongly bonded together so hugh temp is required to seperate tjhe ions and melt crystal, they have high m and b points cos of the energy needed to break nany strong bonds
      - conductivity
        
        ionic compounds do not conduct electricity when theyre solid - the ions are held together ina strong position so they cant carry an electric current
        
        When melted or dissolved in water, ionic compounds conduct electricity because the ions are free to move and carry the current. e.g. Sodium chloride is soluble in water and the solution conducts electricity.
- - - - By ordering the elements strictly according to atomic mass, he was forced to put some elements into groups having dissimilar properties. As a result, his table was not accepted by the scientific community.
      - newland system worked quite well with lighter elements but broke down w heavier elements
        
        he made incorrect assumption that all elements had been discovrerd - the discovery of one more eleemnt would throw out the whole idea of octaves
        
        why was newlands table rejected
        
        In order to make the repeating octaves system work in certain cases Newland had to place two elements in one space.
        
        Newlands’ classification system grouped heavier elements with dissimilar properties together.
  - - - published the table in order of increasing atomic mass
      - showed that elements of similiar properties recurred at regular intervals
      - The vertical columns of similar elements are called groups and the horizontal rows of elements are called periods.
    - - Mendeléev was more confident on his proposal and was prepared to take risks. Where the pattern didn’t work he left gaps in the table so that similar elements would fall in the same vertical column.
      - He claimed that in due course, these gaps will be filled by elements that had not yet been discovered.
      - Within his lifetime some of these elements were discovered the properties of which coincided very closely to the predictions made by c.
  - - - 8 groups in total
      - elements in the same group have similar chemical properties cos of they have same numebr of electrons in outer shell
    - - 1 - alkali metals
      - 2 - alkaline earth metals
      - 7- halogens
      - 0 -nobel gases
  - - - the periods reperesent the energy shells which these atoms outer electrons associated with