Periodic table Flashcards
What did Doberiener notice?
he noticed that elements could be grouped into triads - three elements that have similar properties
who were the three scientists who contributed in the making of the periodic table?
Doberiener , Newlands and Mendeleev
what was the problem with Doberiener’s method?
Not all elements had the same properties
What was Newland’s idea?
He arranged the elements in atomic weight and noticed that every 8th element have similar properties
what was the problem with Newland’s idea?
It only worked for the first 20 elements
What were the 2 key ideas Mendeleev produced?
- elements with with similar chemical reactivities and similar properties were grouped together in columns called groups
- Elements arranged in atomic weights (some exemptions)
Why did Mendeleev’s idea work?
He used his table to predict elements that were yet to be discovered
if an atomic structure has 1,2,3,4 electrons on the outer shell what is it?
It is a metal
if an atomic structure has 5,67,8 electrons on the outer shell what is it?
It is a non metal
how do metals and non metals react?
Metals react by losing electrons
non- metals react by gaining electrons
are the oxide of metals acidic or alkaline?
alkaline
what group are the noble gases in?
They are in group 0
why are noble gases unreactive?
because they have a stable arrangements of electrons - a full outer shell
Most abundant noble gas?
Argon- makes up 1% of the atmosphere
why are noble gases in their group?
The outer shell is full so they have to have another shell with 0 in
what are the elements in Group 1?
They are alkali metals
what characteristics do group 1 elements have?
single electron on the outer shell
what happens to Group 1 when they react with water ?
- fizzes (hydrogen gas releases)
- metal floats
- moves across surface
- melts and turn int a ball (exothermic reaction)
Trend in reactivity of group1?
reactivity increases down the group
what is the reason for the trend in reactivity as you go down group 1?
it gets more reactive because the outer shell is more easily lost because :
- more energy levels so the outer shell is further away from the nucleus
- weaker force of attraction between the nucleus and the outer shells
Test for hydrogen
squeaky pop test
where are transition metals located on the periodic table?
The center
transition metals compared to group1?
- higher melting points
- higher densities
-stronger and harder
-less reactive
characteristics of transition metals
- have ions with different charge
- form coloured compounds
- useful as catalysts
