How can you tell that the halogens are non-metals?

Question

and why are bromine and clorine so much denser than fluorine and clorine.

sorry didnt realise i had put clorine twice!
: /
the first question is written straight from the sheet that ive been trying to answer.

Answer 1

OK. Let me handle the 2 questions seperately

(1)Halogens, my dear, are non metals. It can be proved by stating that their respective oxides turn blue litmus red. Also, their aquaues solution gives hydrogen. Metals react with them to form salts and evolve hydrogen. Any other proof?

(2)So many typing mistakes! Read your question yourself now. Why is clorine denser than clorine. I bet even clorine doesnt know. So I am anwering only about bromine and fluorine. Bromine is denser than fluorine because its atomic mass unit (amu) is 35 whereas that of fluorine is just 9. Know to understand this you must know what density is. As for keeping clorine in mind, the density goes like this-
Br > Cl > F.
Try to get the modern periodic table and study it

Answer 2

Metals are elements that display metalic properties, sounds obvious, but their are elements that only display some metalic properties. Diagonally down from Boron is the general breaking point, but this is the grey area.

some one has given you the test for Halogens, so I won't repeat.
Additionally the halogens, as they are only short of one electron they are only likely to form salts (ionic bonds) or covalent bonds (sharing), metals typically form a sea of electrons, where they share electrons in an easy come easy go manor, hence the ability to conduct- a major feature of metals. The covalent bond results in molecules of two atoms, hence them mainly existing as gases. So you can predict from the position in the periodic table and their electron configuration that they are unlikely to be metals, and you can test them physically for metalic/ nonmetalic properties.

Density is due to the messy orbitals of the electrons and the charge from the nucleus.

as you go down the group, the atoms become more massive, but the average distance of electron orbitals from the nucleus doesn't increase that dramatically, so they get heavier, but they don't get much bigger.

Answer 3

They form molecules, and don't have metallic bonding. They don't conduct electricity.

Bromine and iodine have much heavier atoms than chlorine and fluorine. At room temperatue, bromine is a liquid and iodine is a solid, whereas chlorine and fluorine are gases. Hence the differences in density.

Answer 4

Metals are shiny materials they have a lustre and conduct electricity. Halogens do not hence they are non-metals.

Answer 5

there all gases its something to do with the amount of oxygen in them

Answer 6

halogens are gases

Answer 7

because they're in the 18th group...and they are gases..
checkout this web- highschoolchemistry.com

Answer 8

Halogens are gaseous, they don't look metallic do they!!!!!

Answer 9

halogens are gases.

Answer 10

I can't tell