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[Banks]

So, here's what I got so far...

 

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True/False, if the statement is false, correct it. I wrote my answer in brackets...

 

T - All matter is composed of atoms

 

F - Electrons are positively charged, protons are negatively charged. (Electrons are negatively charged, protons are positively charged)

 

T - Atoms combine to form compounds

 

T - Most of the mass of the atom is in the nucleus

 

F - All particles of the nucleus are charged (Only neutrons are negative)

 

T - All halogens can become anions

 

F - Magnesium has more energy levels than Aluminum (Opposite)

 

T - Ba has 2 valence electrons

 

F - The molar mass of copper is 58.93 g/mol (63.55 g/mol)

 

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Write the formula for calculating mass number: mass # = # of neutrons + atomic #

 

Complete the table (Element name, Mass Number, Number of Protons, Number of Neutrons)

 

Chromium - 52, 24, 28

Magnesium - 24, 12, 12

Iron - 55, 26, 29

Calcium - 42, 20, 22

Chlorine - 35, 17, 18

 

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How did I do/doing so far?

 

Thanks guys.

 

I'm confused, how do I determine the group name for element Sulfur? And the number of valence electrons for it as well...

Edited February 12, 2012 by Banks

[rktpro]

I'm confused, how do I determine the group name for element Sulfur? And the number of valence electrons for it as well...

 

The atomic number of sulphur is 16. The Electronic Configuration would be 2,8,6

The no. of shells determine the period.

The no of valence electrons determine the group. But, here add 10 to 6. Group would be 16 or VI. I suppose you too have studied short form of periodic table.

[Banks]

The atomic number of sulphur is 16. The Electronic Configuration would be 2,8,6

The no. of shells determine the period.

The no of valence electrons determine the group. But, here add 10 to 6. Group would be 16 or VI. I suppose you too have studied short form of periodic table.

 

Hi thanks for the reply; I am studying the periodic table at this point. So, Sulphur has 16 protons, and valence electrons is 16? Since sulphur is in group 16 then?

 

Here's something I don't understand...why is this:

 

How many valence electrons does magnesium have? - 2

 

How many in fluorine? Nitrogen? Carbon? - 7, 5, and 4

 

Why 2? Why 7 for fluorine and 5 for nitrogen and 4 for carbon? Can anyone please explain in simple words? How would I determine the number of valence electrons for sulfur, oxygen, hydrogen, aluminum, and magnesium?

 

It's from my questions and answers notes I wrote from my class.

 

Unless I wrote it wrong, fluorine should be in 17 since it's in group 17 and nitrogen should be 15 since it's in group 15 and carbon should have 14 valences since it's in group 14?

 

I need the group name for Sulfur, clearly I can't determine this...

[hypervalent_iodine]

Valence electrons only account for electrons found in the outer most 'shell', or highest energy level. The total number of electrons in nitrogen is 7 (not 15, I'm not sure where you got that number from), but 2 of those electrons are not valence electrons. They are found in the 1s orbital, whereas the rest are found in the 2s and 2p orbitals. Similarly, fluorine contains 2 electrons in the 1s orbital, 2 electrons in the 2s orbital and 5 electrons in the 2p orbitals, giving it a total valence electron count of 7.

 

It might be worth reading the wiki article on valence electrons, or preferably a chemistry text book if you have access to one.

[mississippichem]

You should read about the Aufbau Principle, particularly the Madelung Rule. You'll find that the periodic table is arranged in a very specific way. Elements are in "blocks" that correspond to the angular momentum quantum number, [imath] \ell [/math] of their highest energy valence shell. The orbitals fill from left to right in the periodic table as well.

 

Nitrogen is in the "p-block" and is the third member of the p-block in period 2 so it's configuration is [math] [He]2s^{2}2p^{3} [/math].

Edited February 13, 2012 by mississippichem

[DrRocket]

So, here's what I got so far...

 

-------------------------------------------------------------------------------

 

True/False, if the statement is false, correct it. I wrote my answer in brackets...

 

T - All matter is composed of atoms

 

F - Electrons are positively charged, protons are negatively charged. (Electrons are negatively charged, protons are positively charged)

 

T - Atoms combine to form compounds

 

T - Most of the mass of the atom is in the nucleus

 

F - All particles of the nucleus are charged (Only neutrons are negative)

 

T - All halogens can become anions

 

F - Magnesium has more energy levels than Aluminum (Opposite)

 

T - Ba has 2 valence electrons

 

F - The molar mass of copper is 58.93 g/mol (63.55 g/mol)

 

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Write the formula for calculating mass number: mass # = # of neutrons + atomic #

 

Complete the table (Element name, Mass Number, Number of Protons, Number of Neutrons)

 

Chromium - 52, 24, 28

Magnesium - 24, 12, 12

Iron - 55, 26, 29

Calcium - 42, 20, 22

Chlorine - 35, 17, 18

 

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How did I do/doing so far?

 

Thanks guys.

 

I'm confused, how do I determine the group name for element Sulfur? And the number of valence electrons for it as well...

 

 

F - All particles of the nucleus are charged (Only neutrons are negative)

 

This answer (F) is probably correct for your class, which appears to be an introductory chemistry class, but your reasoning is not correct. Neutrons carry a net zero electric charge, and therefore are not negative.

 

But if my assumption about your class is incorrect and you are considering elementary particles to be the "particles" in question then the protons and neutrons in the nucleus are themselves composed of quarks and quarks do carry an electric charge.

[ewmon]

Here’s some information to help resolve some of your inconsistencies with reality in the T/F section not yet revealed here. It’s your job to discern to which of your questions they apply (yes, you still have two wrong answers, so you're scoring a 78 so far in the T/F section). If you can't discover your errors, then come back here and we'll work through it.

 

Polyatomic molecules (see the answer).

 

α and ß particles (see the first reply).

[Banks]

Thanks for the replies, guys.

 

Here is the last question,

 

What is the meaning of "reactivity"? Which groups would you expect to be more reactive than others and why?

 

I wrote,

 

"Reactivity" depends on the number of electrons required to get to the nearest complete energy level.

 

As for the second question, how do I determine this?

 

Thanks again.

[mississippichem]

 

"Reactivity" depends on the number of electrons required to get to the nearest complete energy level.

 

 

If you can answer this question completely you are a professional chemist .

 

That's one thing to consider. There is also polarizability, steric effects, effective nuclear charge overpotentials required[redoc processes], kinetic and equilibrium considerations.

 

In general "reactivity" is the thermodynamic tendency for something to undergo a chemical reaction with something else. It kind of looses meaning with the lack of another reactant IMO.

 

I'm sure your answer will be sufficient or close if this is an elementary highschool chemistry course.

[PositronElectron]

Hi Banks,

 

I suggest you watching this video on electron orbitals (electron hybridization) to get a better understanding of energy levels in the atom. Electron configuration depends on the number of orbitals, determining the number of so-called electron shells. The number of electron shells is determined by the given period number. Valence only shows how many electrons are on the outer shell, or more precisely, on the outer orbital of the atom, determining how many electrons the atom can give over to an oxidant in a chemical reaction.

 

As another member has already mentioned, chemical elements are categorized into blocks, based on the shape of their outer orbital, namely there are s, p, d and f elements. Orbital shapes are as follows: s, p, d, and f. Now imagine a x, y and z coordinates as in a 3-dimensional space. Each orbital carries sub-orbitals; the s- orbital is alone, there are 3 p-orbitals respectively residing on the x, y, and z coordinates; there are 5 d-orbitals... and so on (Do watch the video for a graphic representation). The number before the symbol for the corresponding orbital shape, say, 1s, determines the number of the electron shell, in this instance it is 1. (will provide with an example below). For example, on the 1st electron shell, the maximum allowed number of electrons is 2, and the first electron shell consists of only one orbital - a spherical s orbital, which itself can accumulate only 2 electrons (note that the two electrons form A PAIR, and a pair is formed with TWO electrons of opposite direction! if the number of electrons doesn't divide evenly by the number of sub-orbitals in an orbital, then the uneven electrons have higher energy and are alone one one orbital. They have higher energy because a stabile state would be that of 2 maximum electrons on a sub-orbital); On the 2nd electron shell, the maximum allowed number of electrons is 8, however, the number of orbitals (!) (or the shape of electron movement), will be different.

With each electron shell, the number of orbitals increases by 2.

Each orbital has their own level of energy (which is responsible for formation of the orbitals).

Energy increases in the following order, which is also the order of electronic fulfillment (which orbital 'carries' the next electrons): 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p...

 

Now, with each electron shell, a new orbital adds up. With the first electron shell, there is just only one, s-orbital; with the second electron shell, there's already an s and a p orbital.

Let us take Barium for an example.

Barium is an s-element, because the last of his orbitals is the s-orbital of the 6th electron shell.

Barium's atomic charge is +56, so the number of electrons is also 56 which makes the atom neutral.

Barium's electron position per energy levels is 2) 8) 18) 18) 8) 2) - with 2 electrons on the first electron shell, 8 on the 2nd, etc...

Electron configuration for barium:

1s²2s2p63s2p6d104s2p6d105s2p66s2 (the last orbital shows that barium is an s-element)

I will return tomorrow to explain this further if needed.

Element's reactivity depends on the activity of the element. An element is more active than another element if its atomic radius (distance from the atomic nucleus to the last electron orbital) is bigger than the other element's. Why does it show that the element is more active? Because the bigger the radius, the less energy the last orbital will carry, and so it will be easier for the atom to give over electrons than receive because the electromagnetic force is weaker.

[ewmon]

Thanks for the replies, guys.

Banks, did you find the two mistakes I indicated?

[Banks]

I'm confused, "which groups would you expect to be more reactive than others and why?"

 

Is it metals, or metalloids or non metals, or just noble gases? Or both metals and non-metals? Or alkaline metals and alkaline earth metals?

 

My textbook doesn't really specify what makes less "stable"....

 

Ok so those elements that do not have outer energy levels filled, are most reactive - am I right? Which group is that?

 

Ok I got it so, I wrote, "Alkali metals are likely to be more reactive than others, because this group has less electrons in energy shells".

 

THERE! Nailed it.

 

(Hopefully)

 

Banks, did you find the two mistakes I indicated?

 

I fixed the first one, sir - "Atoms are the smallest part of an element that still has the properties of the element", as atoms do not combine to form compounds...

 

F - All particles of the nucleus are charged (Only neutrons are negative)

 

This answer (F) is probably correct for your class, which appears to be an introductory chemistry class, but your reasoning is not correct. Neutrons carry a net zero electric charge, and therefore are not negative.

 

But if my assumption about your class is incorrect and you are considering elementary particles to be the "particles" in question then the protons and neutrons in the nucleus are themselves composed of quarks and quarks do carry an electric charge.

 

Right thank you, neutrons are neutral as they are neither positive nor negative therefore no charge!

Edited February 15, 2012 by Banks

[ewmon]

I fixed the first one, sir - "Atoms are the smallest part of an element that still has the properties of the element", as atoms do not combine to form compounds...

 

What I meant was:

1. The link on polyatomic molecules was meant to show you that atoms often combine to form molecules that are not compounds.
   
2. The link on alpha and beta particles was meant to show you that these particles are matter but are not composed of atoms.
   

[PositronElectron]

Banks,

The link on electron hybridization should have been this one, I am new to this site and a some problem occurred whilst I tried to post that link.

The video not only showcases how electrons reside on different orbitals depending on the number of electrons on a certain electron shell, but also how bonds are formed with other atoms and thus showcasing the relations of different electrons in a molecular compound.

 

 

I'm confused, "which groups would you expect to be more reactive than others and why?"

Is it metals, or metalloids or non metals, or just noble gases? Or both metals and non-metals? Or alkaline metals and alkaline earth metals?

 

As I have stated in my previous post, reactivity (in a nutshell) depends on the radius of the atom. Logically, when the radius of the atom is bigger, it means that the charge of the nucleus is smaller, thus the electrons of the outer electron shell are held in the atom by a weaker force, hence the atom will be more prone to give away electrons than receive them. Reactivity is the ability of the atom to give away electrons to an oxidant in a reaction.

 

• Determining the relative relationship of atomic radiuses
  Chemical elements that carry a smaller charge have a bigger radius than those who have a greater charge. E.g alkaline metals are even more reactive than alkaline earth metals since their charge is smaller than that of alkaline earth metals. Thus they give away the electrons of their outer electron shell. This is what determines which chemical element is more reactive than the other (in an introductory course for anorganic chemistry).
• Charge of the nucleus
  The charge of the nucleus increases from left to right in the periodic table. Thus non-metals are (mostly) oxidants since they receive electrons, they carry a bigger charge hence have the ability to "grab" free electrons.

Edited February 15, 2012 by PositronElectron