C2-The Periodic Table Flashcards
how was the periodic table developed
John Dalton arranged elements in the order of the atomic weights
John Newlands - he realised that every 8th element had similar properties - however when he made the periodic table he didn’t account for the fact that elements were still being discovered so this trend was only valid until calciumm
Dmitri Mendeleev arranged the 50 elements so that their patterns were seen AND he left spaces for elements that weren’t discovered yet
Some problems he faced:
at this time the noble gases were not yet discovered
So, he had problems with where to put argon
At the start of the 20th century, they arranged elements in order fo the order of their proton number
properties of metals
Properties of metals:
can conduct heat and electricity
ductile (means they can be drawn into wires)
malleable
high MP/BP
Sonorous
why are noble gases stable?
Why are noble gases stable?
Because they have a full outer shell (8 electrons on the outer level)
When something doesn’t have a full outer shell, it is unstable, and so reacts in order to gain a full outer shell
SO, as noble gases already have a full outer shell, they are very ureactive
This is why they travel solo - the gases exist as single atoms instead of diatomic molecules
Diatomic molecules = molecules that exist as two atoms (O2, H2, N2, Cl2, Br2, Fl2)
molecules = two or more atoms that are covalently bonded together
The BP of noble gases increases as you go down the group
what is melting point and boiling point
MP= the temperature at which a substance changes from solid to liquid or from liquid to solid
BP =the temperature at which a substance changes from liquid to gas or from gas to liquid
what is group 1 called
Group 1 is called the alkali metals
what is group 2 called
Group 2 is called the Earth alkali metals
why are alkaline metals stored in oil?
All the alkali metals are very reactive –> they are stored in oil to stop them from reacting with the oxygen in the air, which forms a layer of metal oxide on the surface of the metal (looks black)
How does the reactivity of group 1/group 7 change as you go down the group - 3-4 marks
In group 1/7, the elements react by losing/gaining electrons. As you go down the group, the number of shells increases, so the effect of shielding increases, so the attraction of the nucleus on the outer electron decreases, making it easier/harder to lose/gain an electron. Also, as you go down the group, the distance between the nucleus and outer electron increases, reducing the attraction between the positive nucleus and negative electron, which also makes it easier/harder to lose/gain an electron. So, group 1/7 elements’ reactivity increases/decreases in as you go down the group.
