Please help!

[Courtney]

Hi everyone! I am a little bit stuck on these questions.

 

Use the concepts of electronegativity and polarisation to interpret the bonding in (a) AgBr and (b)HBr.

 

Using the atom of chlorine - 35 explain the terms (a) mass number and (b) electron configuration.

(ii) How can the idea of electron configuration be used to explain chemical reactivity?

 

Can anybody help?

 

Thank you for taking the time to read this.

[encipher]

Hi everyone! I am a little bit stuck on these questions.

 

Use the concepts of electronegativity and polarisation to interpret the bonding in (a) AgBr and (b)HBr.

 

Electronegativity is a measure of howe much an atom attracts electrons in a chemical bond. When molecules form, electronegatity plays a role in determining the type of bond that will form. If the difference between the electronegatvity is not great, then atoms can share electrons in a covalent bond or polar covalent bond (since often bonded atoms dont have the same electronegativty, although they could, polar covalent bonds can form. Do not mix this up with the polarity of the overall molecule, because even though there could be a difference in polarity internally, the overall molecule could still be neutral) . However if there is a great difference in electronegativity, the electron will be transferred permenantly to that with the greater electronegativty, forming an IONIC bond.

 

Polarity of the molecule refers to IMAF (intermolecular attractive forces) which can affect a lot of things such as boiling point, melting point etc.. I cannot go into detail explaining all of these IMAFs because it would be very long, you should look it up in your text.

 

Hopefully this will help you answer the question regarding HBr and AgBr.

 

 

Using the atom of chlorine - 35 explain the terms (a) mass number and (b) electron configuration.

(ii) How can the idea of electron configuration be used to explain chemical reactivity?

 

The mass number is the number of neutrons + protons in an atom.

The electron configuration of Chlorine is [Ne][MATH]3s^23p^5[/math]

That means it has 7 valence electrons. In order for it to acheive a state of maximum stability, it would be 'most convenient' for it to gain an electron and completly fill the P orbital. Therefore chlorine would most likely react with anything that is able to provide that one electron. You could go into more detail regarding reactivity. This is jut a starting point for you.

 

 

Hope this helps.

[Courtney]

The second part of the question I understand now, but I'm still stuck on the first part.

[RyanJ]

I'll see if I can explain (but don't count on it )

 

Electronegativity is a measure of how much an atom tries to draw electrons in a bond towards its self. The periodic trend for this is going across a row in a periodic table we generally increase the elecronegativity of the atom. This falls of after group VI because then we have the noble gasses who's electronegativity is 0.

 

So lets look at one of your examples: [ce]HBr[/ce]

 

In this molecule we have a hydrogen bonded too a halogen; bromine. In this case bromine is the most electronegative (with a value of 2.8 compared too the value 2.1 for hydrogen) and so the electrons in the H-Br bond will be more drawn towards the bromine than the hydrogen. This means the bond is polarised towards the bromine molecule. From here we can actually calculate the bond type by working out the difference in electronegativity between hydrogen and bromine but I don't think you need that based on your question.

 

Just in case your interested this bond is a strongly covalent bond, we know this because: [math]|2.8-2.1| < 2[/math] If the electronegativity difference is less than two the bond will show gradually more and more covalent characteristic, if its above 2 then it will show more and more ionic characteristics. If its exactly two the bond will act as both a covalent and an ionic bond in varying cases

 

Not sure if that helps at all.