the periodic table

• Dalton's ideas about matter:

  -All matter are made out of atoms

  -Atoms cannot be made or destroyed

  -Atoms of same element are identified in size and mass

  -During chemical reactions, atoms are rearranged to form new products

  -Different elements have different types of atoms.
• Metals:

  -Solid

  -Shiny, malleable, ductile, and sonorous

  -Good conductors are heat and electricity

  -Have high melting points and densities
• Non-metals:

  -Gases or liquids

  -Dull, brittle, not sonorous

  -Poor conductors of heat and electricity

  -Low melting points and low densities.
• First suggestion of how elements were arranged was by John Dalton in 1808. He arranged the elements in order of their masses, which had been measured in various chemical reactions.

  He published the table of elements in his book "A New System of Chemical Philosophy".
• 2nd suggestion of how elements were arranged was by John Newland in 1864

  He also arranged them in order of mass but noticed that the properties of every 8th element were similar. Therefore, he created a table showing groups of 8, but did not take into account that scientists were still discovering new ones.
• 3rd suggestion of hwo atoms were arranged was suggested by the Father of the Periodic Table, Dmitri Mendeleev in 1869.
• Dmitri Mendeleev was a Russian chemist and constructed the Periodic Table.

  He arranged them according to increasing atomic mass and put elements with similar properties in Vertical columns - groups.

  He arranged the elements in rows called periods.

  He also left gaps in his table for elements to be discovered.
• Another suggestion of how atoms were arranged was suggested by Henry Mosely in 1913.

  He proposed it from his X-ray studies.
• Modern Periodic law states that chemical and physical properties of elements are the periodic function of their atomic numbers.
• In the periodic table, the metals are in the left and in the centre while non metals are in the right.
• There are similar elements in the groups of the periodic tables, mainly in the boiling and melting point, and density (the amount of mass something has for its volume).
• The idea that matter is made out of tiny particles was over 2400 years ago, and Democritus called the particles atomos (indivisible)
• Physical properties of of matter:

  -Colour, density

  -Conduction of heat and electricity

  -Malleability

  -Ductility

  -Melting and boiling point.
• Physical changes have no change in mass and no new substances are formed. Usually reversible.
• Chemical changes usually occur when there is a color change, a gas is released, energy is released.
• Chemical properties refer to how the substance react with other substances.
• The number of protons in an atom is known as the atomic number. Atomic mass includes the protons, neutrons, and electrons of an element