Periodic Table

• Elements in periodic table are arrange in order of proton number
• the columns are known as groups and the rows are known as periods
• metals are on the left of the periodic table and non-metals are on the right
• each element in the same group has the same number of electrons in its outer shell these are valency electrons
• The melting and boiling point in the periodic table increases towards group 4 then decreases to group 8
• metallic character increases down the group
• elements in the same groups often have similar properties
• Group 1 metals are known as alkali metals
• The trends down group 1 metals(alkali metals) include:

  Metals get softer down the group

  Melting and boiling point decrease down the group

  Density increases down the group
• When group 1 metals react with water they form hydrogen and a solution of alkali metal hydroxide
• Chemical reactivity of alkali metals increases down the group
• Rubidium reacts most violently in water followed by potassium, sodium and potassium
• Group 7 elements are known as halogens
• Trends of group 7 elements include:

  Color gets darker down the group

  State of mater goes from solid to liquid to gas down the group

  Melting and boiling point increase down the group
• Halogens react with metals to form halides
• Chlorine reacts with potassium bromide to turn orange
• Chlorine reacts with potassium iodide to turn brown
• bromine reacts with potassium iodide to turn brown
• Reactivity of halogens decreases down the group
• A more reactive halogen displaces a less reactive halogen in a displacement reaction
• Noble gases have a full valence shell of electrons, making them very stable elements
• Moving down the group of noble gases, the number of electron shells increases by one, making the atoms bigger
• The size of noble gas atoms affects their boiling points; larger atoms with more electrons have higher boiling points
• Noble gases are colorless and monatomic, existing as single atoms
• Noble gases are hardly reactive and very stable due to their full valence shells
• Helium is used to fill party balloons and airships due to its low density compared to air
• Krypton is used in lasers for eye surgery
• Xenon is used in lamps that require a very bright light
• Neon emits a bright orange light when an electrical current is passed through it, used in neon signs
• Density of noble gases increases down the group
• General properties of transition elements:

  • Very hard and strong metals
  • Good conductors of heat and electricity
  • Have very high melting points and are highly dense metals
• Coloured compounds of transition elements are responsible for pigments in paints, colours of gemstones and rocks
• Transition elements are extensively used as catalysts due to their ability to interchange between a range of oxidation states
• Transition elements are also used to form coloured compounds in dyes, paints, stained glass, and jewellery
• Transition elements have more than one oxidation number, known as variable valencies