# MO diagram of helium molecule. calculate the bond order.

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## Related Questions:

### I need to 225 cubic feet of helium. How many pounds is that? Thanks!

The difference in the up and down force is 0.069 pounds. Therefore each cubic foot of helium could lift 0.069 pounds. In order to lift 100 pounds (which would include the weight of your load, the balloon, and the helium) you would need 1449 cubic feet of helium

Aug 23, 2017 | Office Equipment & Supplies

### What is the definition of isotope

A molecule that has extra or less neutrons this changing its behavior. Eg Trillium is helium with a spare neutron, and is radioactive where helium is not.

Jun 14, 2016 | Computers & Internet

### Why does liquid expand when it freezes?

Water is made of up molecules that are very close to one another. They are forced together because of something called a bond. As water cools down, the molecules start to organize themselves into shapes that are commonly known as crystals. Since the crystals are not as close together as the molecules would be in liquid form, water takes up more space frozen.

Feb 18, 2013 | Liquid Fence Freeze Pruf Qt RTU

### How many grams of aluminum acetate contain 2.24 x 1022 atoms of hydrogen?

1 Look up the formula for the aluminum acetate.
2 Count the number of Hydrogen atoms per molecule: Call that nH.
3 Dividing 2.24*10^22 by nH you get the number of molecules of acetate.
4. Divide that number by Avogadro's Number to obtain the number of moles required.
5. Multiply the number of moles by the molecular mass of the aluminum acetate (look it up or use the periodic table to calculate it), you will get the mass of aluminum acetate that contains 2.24*10^22 hydrogen atoms.

Sep 14, 2011 | Texas Instruments TI-84 Plus Calculator

### It wont turn on

You are considering buying bonds in ACBB, Inc. The bonds have a par value of \$1,000 and
mature in 37 years. The annual coupon rate is 10.0% and the coupon payments are annual. If
you believe that the appropriate discount rate for the bonds is 13.0%, what is the value of the
bonds to you? (Hint: Bond value - annual pmts)

Jan 23, 2011 | Texas Instruments TI-30XA Calculator

### Estimate the bond energy' S-F' in SF6.the standard enthalpy of formation of SF6(gas),S(g),F(g) are-1100kj/mole,275kj/mole,80kj/mole respectively

What is the S-F bond energy in SF6 given DHfo for each of the reaction components?

For this problem you must first calculate the change in enthalpy (heat transfer, delta H under standard conditions) for the conversion, S(g) + 6F(g) => SF6(g) OR for the reverse reaction, it really doesn't matter, because the numerical value will be the same, regardless. Once you calculate the heat transferred, you will be able to say that the amount of heat transferred was the amount of potential energy trapped in all of the S-F bonds, all six of them in the molecule. So, to obtain the answer asked for (the energy content on one S-F bond), all you will have to do is divide by 6.

The above is a logical approach, because all six of the S-F bonds are identical. This is so, because, according to VSEPR theory (look it up for more background on that, if you are interested), you can predict that its molecular geometry is "octahedral" with the central sulfur atom having "sp3d2 hybridization."

Here is how you set up the problem:

First write the balanced chemical equation with the given heats of formation (in kJ) written under each of the reaction components:
S(g) + 6F(g) => SF6(g)
275 6(80.) -1100.

Note: I am assuming that each of the above quanties is good (i.e., known) to at least the unit's place; that is, + or - 1 kJ. This reasonable assumption allows me to unambiguously indicate the number of sig figs in each quantity - an important consideration for proper rounding off of the final answer.

Recall that the sum of the product values minus the sum of the reactant values, each component multiplied by its corresponding coefficient will give the net enthalpy ("reaction enthalpy") of the reaction as written. In this case, there being only one product, the reaction enthalpy is:
-1100 - (480 + 275) = - 1855 kJ. From this, we can see that as S and six Fs are combined, 1,855 kJ of heat are released into the surroundings (that is, an exothermic reaction). The amount of heat released informs you of the combined bond energy of ALL six S-F bonds.

A good rule to remember: As bonds are formed, energy is always released (an exothermic process). As bonds are broken (as in the reverse reaction), the same amount of energy is being absorbed (an endothermic process).

Therefore, in conclusion, one S-F bond has a bond energy of 309.17, which is more properly rounded off to 309 kJ.

Recall that the rule for rounding off when adding or subtracting is to make sure that the final answer has the same precision as the values used to calculate it. Since each given value was good only only to the last unit

Nov 22, 2010 | MPS Multimedia QuickStudy Chemistry for PC

### What is the electron dot diagram for nitrogen

The electron-dot structure (also known as the "Lewis dot structure") for N is shown below: The red dots represent electrons that comprise the atom's 5 valence electrons. Recall that the valence (outermost) electrons are those that are involved in chemical reactions of bonding. The rule you should apply to drawing this electron dot structure is to first draw (or imagine) a rectangle around the atom's symbol, letting the rectangle represent the atom's core electrons (not shown), those within the atom's inner (s) shell. Then place one electron on each side. That leaves the remaining electron to be placed on one of the already occupied sides to give the electron pair.

It doesn't matter what side you place this 5th electron, because the final result is the pattern shown above, 3 single dots and one pair of dots, which neatly reveals the bonding power* of N (3) - and the existence of the one electron pair, which predicts special types of reactivity you will probably appreciate in more advanced topics of this element's behavior.

*The single electrons are more reactive than the electron pair, and will readily form bonds with other atoms, such as H. This allows you to predict that N and H atoms will combine to form NH3.

How do you know there are 5 valence electrons? For the answer, refer to the following partial image of the Periodic Table of the Elements I drew using Word and SnagIT software:

Notice the number-letter labels above each column ("group") of elements, for example "5A." The letter A indicates the groups of "representative" elements, the most common elements studied in general chemistry courses. The numbers before the "A" represents the number of valence electrons surrounding each element's atoms. For example, hydrogen has one valence electron, nitrogen has 5 valence electrons, and oxygen has 6 valence electrons.

Using the rules described above for drawing electron-dot structures, how many single dots and double dots should be drawn around H? Around O? Can you predict the bonding power of each of these atoms? What molecular compounds do you predict would be formed from the reaction of H and H? What molecular compound do you predict would form between combining H atoms and O?

Hints:
Reactions tend to occur that cause the single electrons (dots) to pair up. This occurs because paired electrons are much more stable than single electrons. A strong driving force for a reaction is the going from a less stable state to a more stable state. Hydrogen atoms from H2 molecules (diatomic molecules). H and O atoms combine to form dihydrogen oxide, also known as water!

Summary:
• A very simple set of rules allows you to predict the electron dot structures of the representative elements.
• The electron dot structures are very useful, because they can allow you to predict the bonding power of each representative element.
• They are also useful in guiding your prediction of the compositions of molecules that can form during reactions between their atoms (that is, how many of each element in the molecule).
• In more advanced topics you will also be able to use electron-dot structures to predict the shapes (or geometry) of molecules, including bond angles!
• So, learning the skill of drawing electron-dot structures is very important to mastering chemistry!

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Nov 04, 2010 | Scientific Explorer My First Chemistry Kit

### I want an answer to a question that "why ice sticks to hand?"

The water molecules on your skin will bond and freeze with the water molecules on the ice

Oct 27, 2010 | Computers & Internet

### How do I calculate this question with the fx-115es. Find the number of moles of nitrogen in 1.75 mol N2H4?

You have 1.75 moles of hydrazine or 1.75xNa molecules of the substance. Since each molecule of N2H4 contains 2 atoms of nitrogen 1.75Na molecules contain 2x1.75xNa atoms of nitrogen. The number of moles of nitrogen is 2x1.75xNa/Na, which leaves 2x1.75 or 3.5 moles.
Your answer: 1.75 mol of hydrazine contain 3.5 mol of nitrogen atoms.

Sep 23, 2010 | Casio FX-115ES Scientific Calculator

### Present value of an annuity due

You are considering buying bonds in ACBB, Inc. The bonds have a par value of \$1,000 and
mature in 37 years. The annual coupon rate is 10.0% and the coupon payments are annual. If
you believe that the appropriate discount rate for the bonds is 13.0%, what is the value of the
bonds to you? (Hint: Bond value - annual pmts)

Sep 13, 2010 | Casio CFX 9850GB Plus Calculator

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