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2 years ago

• An element in group 2, period 4 has similar properties with

Chemistry

1 answer:

babymother [125]2 years ago

7 0

Answer: Elements in Group 2

Explanation: The periodic table was arranged by Dmitri Mendeleev specifically around similarites in their chemical behaviors. He found that as atomic number increases, at some point an element starts to react in a manner similar to a previous one. When that happened, he would place the larger element under the smaller one, and eventually noticed a periodicity in the table. Elements in a column (Groups) had similiar chemical properties. We know today that these similarities are due to the electron configuration, and that these configurations repeat themselves. He left gaps in the table when he could find an existing element with properties similar to others in that group. I big leap of faith, but it worked. Elements for those missing boxes were eventually discovered.

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The electronegativity of nitrogen (N) is 3.0, while the electronegativity of hydrogen (H) is 2.1. Knowing this, consider how the

Ede4ka [16]

Answer:

NH3 is polar due to the bonds between nitrogen and hydrogen which have different electronegativity and due also to its asymmetrical shape.

Explanation:

NH3 is polar as there are 3 dipoles in the ammonia molecule that do not balance each other out.

Considering the N-H bond which is polar because N with an electronegativy of 3.0, is more electronegative than H, with an electronegativity of 2.1. The is overall asymmetrical shape of NH3

means that the dipoles remains unbalanced and do cancel out each other making the NH3 polar.

4 0

3 years ago

How many moles are in 12 gr of magnesium?

myrzilka [38]

Answer: 0.5 mole Mg

Explanation: solution:

12 g Mg x 1 mole Mg / 24 g Mg

= 0.5 mole Mg

5 0

3 years ago

A certain substance X has a normal freezing point of 5.6 °C and a molal freezing point depression constant Kf-7.78 °C-kg·mol-1.

Harrizon [31]

Answer:

27.60 g urea

Explanation:

The freezing-point depression is expressed by the formula:

ΔT= Kf * m

In this case,

ΔT = 5.6 - (-0.9) = 6.5 °C

Kf = 7.78 °C kg·mol⁻¹

m is the molality of the urea solution in X (mol urea/kg of X)

First we calculate the molality:

6.5 °C = 7.78 °C kg·mol⁻¹ * m

m = 0.84 m

Now we calculate the moles of urea that were dissolved:

550 g X ⇒ 550 / 1000 = 0.550 kg X

0.84 m = mol Urea / 0.550 kg X

mol Urea = 0.46 mol

Finally we calculate the mass of urea, using its molecular weight:

0.46 mol * 60.06 g/mol = 27.60 g urea

7 0

2 years ago

Write a nuclear reaction for the neutron-induced fission of u−235 to form xe−144 and sr−90.

rusak2 [61]

Answer:

235/92U+10n→144/54Xe+90/38Sr+2/10n

Explanation:

The nuclear reaction for the neutron-induced fission of u−235 to form xe−144 and sr−90 is represented by;

235/92U+10n→144/54Xe+90/38Sr+2/10n

In nuclear fission reactions a heavy nuclide is split into two light nuclides and is coupled by the release of energy.

3 0

2 years ago

I NEED THE ANSWER QUICKKK!!!

julsineya [31]

Answer: This is hard to do accurately, but here is my best assessment.

Explanation:

Experiment: B - describes how the experiment was done

Conclusion: A - The data support the prevailing hypothesis

Research: D - This is what we analyzed

Analysis: C - We compared the data

7 0

2 years ago