c2 the periodic table Flashcards
what was mandeleevs periodic table
ordered by atomic mass but some elements were swapped around there were gaps left for undiscovered elements the elements were grouped together by chemical properties with no clear distinction between metals and non metals the problem with this model was it was incomplete and some elements had to be swapped around to fit in appropriate groups
what is the modern periodic table
sorted by atomic number and there are no gaps for all elements up to a certain atomic number have been discovered they are grouped by the number of electrons in the outer shells metals are to the left non metals are to the right
what are the group 0 elements
called noble gases have full outer shells with 8 electrons so dont need to lose or gain electrons they are also very unreactive so exist as single atoms as they do not bond to form molecules their boiling points increase down the group
what are group 1 elements
react with oxygen chlorine and water lithium+oxygen = lithium oxide
lithium+chlorine=lithium chloride
lithium+water=lithium hydroxide + hydrogen
they are called alkali metals because they react with water to form a alkali
what are the group 1 properties
have one electron in their outer shell rectivity decreases down group 1 because the further down you the go bigger the atoms in size and the outer electron is away from the nucleus the melting and boiling point decreases down group 1
what are group 7 elements
called halogens they are non metals that exist as molecules made up of pairs of atoms melting and boiling points increase down the group but the reactivity decreases
group 7 reactivity
reactivity decreases down the group as the atoms increase in size the outer shell is further away from the nucleus the electrostatic attraction from the nucleus to the outer shell is weaker so its harder to gain a electron to fill the outer shell
group 7 displacement
most reactive group 7 elements can take the place of less reactive ones in a compound this is displacement florine displaces chlorine since its more reactive
flourine+potassium chloride=potassium floride +chlorine
