Question classifications of elements (2 Viewers)

mtsmahia · Jul 22, 2009

Hi Guys, just a quick question.

5. Select the group that contains only molecules.
A Water, methane, copper chloride
B Hydrogen, sulfur, argon
C Ethane, lead, diamond, oxygen
D Bromine, fluroine, silicon dioxide, water

Im a bit confused, shouldnt the answer be B and D, cuz cant sulfur, argon be classified as molecules. And same with Bromine, flourine...am i right?

Smilebuffalo · Jul 22, 2009

mtsmahia · Jul 22, 2009

Smilebuffalo said:
B

but cant Bromine and Flourine be taken as molecules

lizajane91 · Jul 22, 2009

yeah but not silicon dioxide

annabackwards · Jul 22, 2009

Definition of a molecule: a sufficiently stable, electrically neutral group of at least two atoms in a definite arrangement held together by very strong (covalent) chemical bonds --> got this from google defining... tell me if i'm wrong.

Using the definition above:
Sulfur doesn't exist as a molecule naturally by itself so it isn't B.
C is completely out of the picture for obvious reasons
It's not A because CuCl2 is ionically bonded.

Therefore it has to be D.

EDIT: If you read on, you'll see that everyone has agreed that the answer is B as S2 does exist and silicon dioxide exists only as a covalent lattice, not just as a molecule.

mtsmahia · Jul 22, 2009

^ why not?, doesnt it have covalent bonds?

mtsmahia · Jul 22, 2009

annabackwards said:
Definition of a molecule: a sufficiently stable, electrically neutral group of at least two atoms in a definite arrangement held together by very strong (covalent) chemical bonds --> got this from google defining... tell me if i'm wrong.

Using the definition above:
Sulfur doesn't exist as a molecule naturally by itself so it isn't B.
C is completely out of the picture for obvious reasons
It's not A because CuCl2 is ionically bonded.

Therefore it has to be D.

oh yeah, sulfur cant be diatomic , whoops

annabackwards · Jul 22, 2009

mtsmahia said:
oh yeah, sulfur cant be diatomic , whoops

LOl yeah.

Do you have the answer?

mtsmahia · Jul 22, 2009

annabackwards said:
LOl yeah.

Do you have the answer?

umm, nup, i found it in the SBH prelim exam,

study-freak · Jul 22, 2009

annabackwards said:
Definition of a molecule: a sufficiently stable, electrically neutral group of at least two atoms in a definite arrangement held together by very strong (covalent) chemical bonds --> got this from google defining... tell me if i'm wrong.

Using the definition above:
Sulfur doesn't exist as a molecule naturally by itself so it isn't B.
C is completely out of the picture for obvious reasons
It's not A because CuCl2 is ionically bonded.

Therefore it has to be D.

Noble gases exist in their atomic forms, yet they are also molecules.

mtsmahia · Jul 22, 2009

study-freak said:
Noble gases exist in their atomic forms, yet they are also molecules.

monatomic molecules

study-freak · Jul 22, 2009

mtsmahia said:
monatomic molecules

exactly

mtsmahia · Jul 22, 2009

umm...i came up on another Q

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(A)[FONT=&quot] [/FONT]Burning methane gas; evaporating water
(B)[FONT=&quot] [/FONT]Melting glucose powder; dissolving ethanol in water
(C)[FONT=&quot] [/FONT]Burning magnesium in air; condensing water
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The answer is B, i can understand that becuase the others dont make sense, but i dont get how dissolving ethanol in water is a plysical change?...does anyone know??

(D)[FONT=&quot] [/FONT]Electrolysing water; discolouring silver salts in the presence of light

zeleboy · Jul 22, 2009

mtsmahia said:
Hi Guys, just a quick question.

5. Select the group that contains only molecules.
A Water, methane, copper chloride
B Hydrogen, sulfur, argon
C Ethane, lead, diamond, oxygen
D Bromine, fluroine, silicon dioxide, water

Im a bit confused, shouldnt the answer be B and D, cuz cant sulfur, argon be classified as molecules. And same with Bromine, flourine...am i right?

B
A- CuCl2 exists in an ionic lattice
D- Silicon Dioxide exists in a lattice (quarts = sand)
C- Lead is a metal, exists as a structure with cations stuck together amidst delocalised electrons

study-freak · Jul 22, 2009

mtsmahia said:
umm...i came up on another Q

<META name=ProgId content=Word.Document><META name=Generator content="Microsoft Word 12"><META name=Originator content="Microsoft Word 12"><LINK rel=File-List href="file:///C:%5CUsers%5CTejas%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_filelist.xml"><LINK rel=themeData href="file:///C:%5CUsers%5CTejas%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_themedata.thmx"><LINK rel=colorSchemeMapping href="file:///C:%5CUsers%5CTejas%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_colorschememapping.xml"><STYLE>  </STYLE>1.In which of the following do BOTH processes involve physical changes?
<O> </O>
(A)Burning methane gas; evaporating water
(B)Melting glucose powder; dissolving ethanol in water
(C)Burning magnesium in air; condensing water
<META name=ProgId content=Word.Document><META name=Generator content="Microsoft Word 12"><META name=Originator content="Microsoft Word 12"><LINK rel=File-List href="file:///C:%5CUsers%5CTejas%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_filelist.xml"><LINK rel=themeData href="file:///C:%5CUsers%5CTejas%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_themedata.thmx"><LINK rel=colorSchemeMapping href="file:///C:%5CUsers%5CTejas%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_colorschememapping.xml"><STYLE>  </STYLE>(D)Electrolysing water; discolouring silver salts in the presence of light

The answer is B, i can understand that becuase the others dont make sense, but i dont get how dissolving ethanol in water is a plysical change?...does anyone know??

(D)Electrolysing water; discolouring silver salts in the presence of light

When you dissolve ethanol in water, ethanol does not chemically react with the water or decompose into smaller molecules.
It is simply mixed with water.

study-freak · Jul 22, 2009

zeleboy said:
B
A- CuCl2 exists in an ionic lattice
D- Silicon Dioxide exists in a lattice (quarts = sand)
C- Lead is a metal, exists as a structure with protons stuck together amidst delocalised electrons

Cations, not protons

zeleboy · Jul 22, 2009

study-freak said:
Cations, not protons

soz, yr 11 was ages ago

mtsmahia · Jul 22, 2009

zeleboy said:
B
A- CuCl2 exists in an ionic lattice
D- Silicon Dioxide exists in a lattice (quarts = sand)
C- Lead is a metal, exists as a structure with cations stuck together amidst delocalised electrons

sulfur does not exist as a molecule, so B is not the asnwer, the correct answer is D, Silicon dioxide, exists in a Covalent lattice, hence molecules involved)

randomnessss · Jul 23, 2009

5. Select the group that contains only molecules.
A Water, methane, copper chloride
B Hydrogen, sulfur, argon
C Ethane, lead, diamond, oxygen
D Bromine, fluroine, silicon dioxide, water

A is wrong since copper chloride is ionic and hence, does not occur as a molecule.
B is correct since all of these can form/exist as molecules. Sulfur can exist as a molecule (e.g. S2).
C is wrong since lead is a metal and hence does not occur as a molecule.
D is wrong since silicon dioxide is a covalent network substance. Covalent network structures do not exist as molecules but instead they occur as an infinite 3D array of atoms.

annabackwards · Jul 23, 2009

^
Ah, forgot about Silicon dioxide being a lattice and S2 (industry makes pure sulfur).

The answer is B then

Question classifications of elements (2 Viewers)

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