periodic table Flashcards
key facts
how are the elements arranged in the periodic table?
in order of atomic (proton) number and so that elements with similar properties are in columns
what does the group number tell you about the atoms in that group
the group number is the number of electrons in the outer shell eg all elements in group 2 have 2 electrons in their outer shell
how did Mendeleev improve the periodic table
knowledge of isotopes helped explain why placing elements in the order of atomic weight was not always correct
what is the difference between metal and non metal
elements that react to form positive ions are metals
elements that do not form positive ions are non metals
state the name of group 0 group 1 and group 7
group 0= noble gases group 1=the alkali metals group 7=the halogens
how did the discovery of isotopes affect the periodic table?
knowledge of isotopes helped explain why placing elements in the order of atomic weight was not always correct
how does the reactivity change in group 1
in group 1,the reactivity of the elements increases as you go down the group
properties of the elements in group 0
they are unreactive and do not easily form molecules
describe the properties of group 7 elements changes as you go down the group
as you go down group 7 reactivity decreases,boiling point increases and melting point increases
explain why group 0 elements have the properties they do
their atoms have stable arrangements of electrons meaning they have a full outer shell
how was the periodic table originally organised
order of atomic weight
