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3 years ago

8. Consider the element Scandium, atomic # 21.

Chemistry

1 answer:

yawa3891 [41]3 years ago

4 0

Explanation:

Scandium has atomic number of 21. This means that in it's neutral state its going to have 21 electrons.

a) The full electronic configuration is given as;

1s2 2s2 2p6 3s2 3p6 3d1 4s2

The final electron is placed in the d orbital. The shell is 3d

(b) When scandium has a charge if +1, it has lost an electron. The total number of electrons would now be 21-1 = 20

The electronic configuration would be given as;

1s2 2s2 2p6 3s2 3p6 4s2

The electron in the 3d orbital would be removed.

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Which number label represents the nucleus? 6,5,3,2

vazorg [7]

Answer:

Explanation:

Nucleus is the center or "CEO" of the cell, that holds the cell's DNA and controls the cells' function.

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3 years ago

Read 2 more answers

The total volume of seawater is 1.5 x 1021L .Assume that seawater contains 3.1 percent sodium chloride by mass and that its dens

son4ous [18]

Answer:

Mass in kg = 4.7*10^19 kg

Mass in tons = 5.2*10^16 tons

Explanation:

Given:

Total volume of sea water = 1.5*10^21 L

Mass % NaCl in seawater = 3.1%

Density of seawater = 1.03 g/ml

To determine:

Total mass of NaCl in kg and in tons

Calculation:

Unit conversion:

1 L = 1000 ml

The volume of seawater in ml is:

$=\frac{1.5*10^{21}L*1000ml }{1L} =1.5*10^{24} ml$

$Mass\ seawater = Density*volume = 1.03g/ml*1.5*10^{24} ml=1.5*10^{24}g$

$Mass\ NaCl\ in\ seawater = \frac{3.1}{100}*1.5*10^{24} g=4.7*10^{22} g$

To convert mass from g to Kg:

1000 g = 1 kg

$Mass\ seawater(kg) = \frac{4.7*10^{22}g*1kg }{1000g} =4.7*10^{19} kg$

To convert mass from g to tons:

1 ton = 9.072*10^6 g

$Mass\ seawater(tons) = \frac{4.7*10^{22}g*1ton }{9.072*10^{6}g } =5.2*10^{16} tons$

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3 years ago

Of the first 103 elements, how many have just ine letter in their symbol

malfutka [58]

Answer:

14 elements.

Explanation:

boron

carbon

fluorine

hydrogen

iodine

nitrogen

oxygen

phosphorus

potassium

sulfur

tungsten

uranium

vanadium

yttrium

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3 years ago

After mixing the solutions in a separatory funnel, the stopper should be ________and the liquid should be ________and the layers

sdas [7]

Answer:

The answer is below

Explanation:

The separation technique is used for separating immiscible liquids.

When separating, the stopper has to be removed when draining the lower layer so as to prevent a vacuum. If vacuum is allowed, the draining rate will reduce and stop.

The liquid should be mixed by shaking the funnel and then opening the stopcock so as the vent out gases.

When near interface between the layers, you should set your eye level so that you do not drain up to the second layer.

After completely draining the first layer, the second layer should be collected in a new flask.

After mixing the solutions in a separatory funnel, the stopper should be removed and the liquid should be mixed thoroughly and the layers allowed to separate. When you get close to the interface between the layers, get eye level with the funnel and slow the draining until the first layer is collected. Switch to a new flask to collect the second layer.

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3 years ago

The element lanthanum has two stable isotopes, lanthanum-138 with an atomic mass of 137.9 AMU and lanthanum-139 with an atomic m

dmitriy555 [2]

Answer:

A. there is an isotope of lanthanum with an atomic mass of 138.9

Explanation:

By knowing the different atomic masses of both Lanthanum atoms, we can not tell anything about their occurence in nature. Therefore, all the last three options are incorrect. Because, the atomic mass does not tell anything about the availability or natural abundance of an element.

Now, the isotopes of an element are those elements, which have same number of electrons and protons as the original element, but different number of neutrons. Therefore, they have same atomic number but, different atomic weight or atomic masses.

Hence, by looking at an elements having same atomic number, but different atomic masses, we can identify them as isotopes.

Thus, the correct option is:

A. there is an isotope of lanthanum with an atomic mass of 138.9.

7 0

3 years ago