Chemistry Finals
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Proud to Be Junior! -- 11th Grade Class Forum -- Pan American School of Bahia :: Academic subjects :: Chemistry
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Chemistry Finals
Hello guys,
Here we are, after months of hard work and intense despair, to the Finals.
To make the best of it, you can post any issue or concern about the CHEMISTRY FINALS here
Here we are, after months of hard work and intense despair, to the Finals.
To make the best of it, you can post any issue or concern about the CHEMISTRY FINALS here
Re: Chemistry Finals
What's the VESPR theory?
and a brief definition of ionization energy and electronegativity would be nice! thanks
and a brief definition of ionization energy and electronegativity would be nice! thanks
Bibi- Posts : 32
Join date : 2008-12-02
Age : 32
Re: Chemistry Finals
The VESPR theory states that the atoms are arranged far away from each other, repelling each others. It helps us poor mortals that we are to figure out how to draw compounds, and to give a name to that arragement.
For example: CO2 will be arranged as following: O = C = O
"=" being double link
Carbon has four valences electrons, so it links with four other electons from the two oxygens , letting in total four lone pairs of electrons (on the oxygens)
This figure is said to be Linear
There are also bent, Trigonal planar, tetrahedral, pyramidal, trigonal bipyramidal, octahedral. (see handout for pictures)
-Ionization energy: this is the energy required to form a cation (therefore to lose an electron)
It decreases down the group (Li>Fr) because electrons are further away from nucleus as we go down the group.
It increases from left to right (Mg<Al)
-Electronegativity: this is the ability of an element to attract electrons when it is in a compound.
It also decreases down the group (Li>Fr)
It also increases from left to right (Mg>Al)
For example: CO2 will be arranged as following: O = C = O
"=" being double link
Carbon has four valences electrons, so it links with four other electons from the two oxygens , letting in total four lone pairs of electrons (on the oxygens)
This figure is said to be Linear
There are also bent, Trigonal planar, tetrahedral, pyramidal, trigonal bipyramidal, octahedral. (see handout for pictures)
-Ionization energy: this is the energy required to form a cation (therefore to lose an electron)
It decreases down the group (Li>Fr) because electrons are further away from nucleus as we go down the group.
It increases from left to right (Mg<Al)
-Electronegativity: this is the ability of an element to attract electrons when it is in a compound.
It also decreases down the group (Li>Fr)
It also increases from left to right (Mg>Al)
Re: Chemistry Finals
To calculate the atomic mass unit (a.m.u.) you will be given the isotopes with their abundance in percentages. For instance:
Nitrogen 14 has 99.63% abundance
Nitrogen 15 has 0.37% abundance
You do 14 x .9963 + 14 x .0037 = 14.0037 amu
which is equal to the atomic mass of Nitrogen
Nitrogen 14 has 99.63% abundance
Nitrogen 15 has 0.37% abundance
You do 14 x .9963 + 14 x .0037 = 14.0037 amu
which is equal to the atomic mass of Nitrogen
Bibi- Posts : 32
Join date : 2008-12-02
Age : 32
Re: Chemistry Finals
the SPDF thing...can any one help?
for example Nickel: 1s2 2s2 2p6 3s2 3p6 4s2 3d8 is this right?
if it was Arsenic would the right one be this: 1s2 2s2 2p6 3s2 3p6 4s2 4p3 4d10?
and for example how many orbital does nickel and arsenic have?
for example Nickel: 1s2 2s2 2p6 3s2 3p6 4s2 3d8 is this right?
if it was Arsenic would the right one be this: 1s2 2s2 2p6 3s2 3p6 4s2 4p3 4d10?
and for example how many orbital does nickel and arsenic have?
John- Posts : 7
Join date : 2008-12-03
Re: Chemistry Finals
Nitrogen: 1s2, 2s2 and 2p3
Orbitals:
s = ONE
p = THREE
d = FIVE
f = SEVEN
You have to multiple these numbers x2 because there are 2 electrons per orbital.
Energy level 1 has one orbital: 1 from s
Energy level 2 has 4 orbitals in total: 1 from s and 3 from p
Energy level 3 has 9 orbitals in total: 1 from s, 3 from p and 5 from d
Energy level 4 has 16 orbitals in total: 1 from s, 3 from p, 5 from d, 7 from f
Nitrogen is located in energy level 2 so it has orbitals from energy levels 1 and 2
total 1 + 4 = 5
Arsenic is located in energy level 4 so it has orbitals from energy levels 1, 2, 3 & 4
total 1+ 4 + 9 + 16 = 30
Orbitals:
s = ONE
p = THREE
d = FIVE
f = SEVEN
You have to multiple these numbers x2 because there are 2 electrons per orbital.
Energy level 1 has one orbital: 1 from s
Energy level 2 has 4 orbitals in total: 1 from s and 3 from p
Energy level 3 has 9 orbitals in total: 1 from s, 3 from p and 5 from d
Energy level 4 has 16 orbitals in total: 1 from s, 3 from p, 5 from d, 7 from f
Nitrogen is located in energy level 2 so it has orbitals from energy levels 1 and 2
total 1 + 4 = 5
Arsenic is located in energy level 4 so it has orbitals from energy levels 1, 2, 3 & 4
total 1+ 4 + 9 + 16 = 30
Bibi- Posts : 32
Join date : 2008-12-02
Age : 32
Re: Chemistry Finals
eu ainda n entendi o negoco de orbitals uaheuhaeuaeh
no teste ela vai fzr perguntas como sobre orbitals?
no teste ela vai fzr perguntas como sobre orbitals?
John- Posts : 7
Join date : 2008-12-03
Re: Chemistry Finals
John, I think you need to understand the concept of orbitals ...
Bibi presented this concept very well; what is your question?
Well, if you take a look at the periodic table, it may be easier.
The horizontal rows correspond the levels of energy
These levels of energy are divided into orbitals.
For example the first level of energy only contains one orbital, S.
So you write it: 1(first level of energy) s (the type of orbital) 2 (the number of electrons)
=> 1s2
then second row => 2s2 2p6
third row=> 3s2 3p6
fourth row => 4s2 3d10 4p6
ect ...
That's the basic, tell me your problem with orbitals, it will be easier to solve
Bibi presented this concept very well; what is your question?
Well, if you take a look at the periodic table, it may be easier.
The horizontal rows correspond the levels of energy
These levels of energy are divided into orbitals.
For example the first level of energy only contains one orbital, S.
So you write it: 1(first level of energy) s (the type of orbital) 2 (the number of electrons)
=> 1s2
then second row => 2s2 2p6
third row=> 3s2 3p6
fourth row => 4s2 3d10 4p6
ect ...
That's the basic, tell me your problem with orbitals, it will be easier to solve
orbtals!
Oh john... vou simplificar
cada orbital so pode ter dois electrons, entao os sublevels (s,p,d,f) tem uma quantidade de orbitals diferente.
por isso:
s tem 1 orbital e portanto 2 electrons max
p tem 3 orbitals e portanto 6 electrons max
d tem 5 orbitals e portanto 10 electrons max
f tem 7 orbitals e portanto 14 electrons max
qdo vc quer ver os orbitals no ultimo energy level, vc soma o todas as letras do level (1,2,3 etc) disponiveis.
ou seja.. se quiser saber o numero d orbitals d um sublevel (s,p,d,f) sem memorizar, divida o numero d electrons q podem caber na level por 2
cada orbital so pode ter dois electrons, entao os sublevels (s,p,d,f) tem uma quantidade de orbitals diferente.
por isso:
s tem 1 orbital e portanto 2 electrons max
p tem 3 orbitals e portanto 6 electrons max
d tem 5 orbitals e portanto 10 electrons max
f tem 7 orbitals e portanto 14 electrons max
qdo vc quer ver os orbitals no ultimo energy level, vc soma o todas as letras do level (1,2,3 etc) disponiveis.
ou seja.. se quiser saber o numero d orbitals d um sublevel (s,p,d,f) sem memorizar, divida o numero d electrons q podem caber na level por 2
ana- Posts : 31
Join date : 2008-12-03
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Proud to Be Junior! -- 11th Grade Class Forum -- Pan American School of Bahia :: Academic subjects :: Chemistry
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