periodic table test Flashcards
when were neutrons and electrons discovered?
19th century
what were elements ordered in before the 19th century
by weight
Give 3 differences between the physical properties of the elements in group 1 and those of the t-metals
1) Group one elements are soft and can be cut with a knife, t-metals are hard.
2) Group one elements have a low density and t-metals have high density
3) Group one elements have low melting points and t-metals have high melting points.
what colour and state is chlorine?
green gas
what colour and state is bromine?
brown liquid
what colour and state is iodine?
grey solid
what are group 7’s called?
halogens
why are elements in group 7?
because they have 7 outer electrons
what are the 4 differences between the chemical properties of the elements in group 1 and the t-metals.
1) Group one elements are reactive, t-metals are non-reactive
2) group one elements have colourless compound solutions or white solids, t-metals have colourful compounds
3) Group one elements have a single valency, t-metals have variable valencies.
4) Group one elements are not catalyst, t-metals are catalyst.
why are molecule melting and boiling points so low?
Molecules have weak intermolecular
forces between them and it is these forces that are broken during melting
or boiling
Halogens (like all molecules) have low melting and boiling
points because:
- they are simple molecules (molecular structure)
- little energy is needed to break
- weak intermolecular forces
Melting and boiling points increase down group 7 because:
-the molecules get larger
-intermolecular forces get stronger (as there are more of them)
-more energy is needed to break them
Halogens have similar chemical properties because:
they have same number of electrons (7) in their outer shell
Group 0 ALL have full outer shells, this is why….
- they are all in the same group
- they are nonreactive
why is helium used for balloons and blimps?
- its lighter than air
- it’s non-combustible
why is argon (Ar) used for light-bulbs and not oxygen(O)?
- argon is non-reactive, the metal won’t burn
- oxygen is reactive, the metal will burn