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3 years ago

Explain how scientific observations led to the development of, and changes to, the periodic table.

1 answer:

7 0

The following are scientific observations which led to development and changes of periodic table: Dmitri Mendeleev is the first periodic table organized 63 known element according to its properties, organized into rows and columns and inscribed name, mass and chemical properties on each element. Julius Lothar Meyer who independently worked in Germany with Ernest Rutherford. They experimented with 38 metals and found out that the positive charge of each element nucleus increased by one from element to element and organized the periodic table that tip to modern explanation of atomic number and the recognition of atomic number was the basis for organization of periodic table.

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Electrons are found in energy levels around the nucleus of an atom. Energy levels can also be called ""shells."" The energy leve

melamori03 [73]

Answer:

The first electronic shell or energy level, having n= 1, called the K shell, is the closest to the nucleus.

Explanation:

In an atom, the sub atomic particles called electrons, revolve around the nucleus of the given atom at different energy levels, called shells.

The energy levels or the electronic shells are denoted by the principal quantum number (n) and has the following values n = 1, 2, 3, 4, 5, 6, 7; from the innermost shell to the outermost.

The electron shells are also labelled by the alphabets, K, L, M, N, O, P, and Q, from the innermost shell to the outermost.

Thus the first electronic shell having n= 1, called K shell, is the lowest energy level and is present closest to the nucleus.

Whereas, the last electronic shell having n =7, called Q shell, is the highest energy level and is farthest from the nucleus.

5 0

3 years ago

Will the calculated Molarity of NaOH be too high or too low or unaffected if the following happen: when you answer the question,

vodomira [7]

Answer:

Explanation:

The result will be affected.

The mass of KHP weighed out was used to calculate the moles of KHP weighed out (moles = mass/molar mass).

Not all the sample is actually KHP if the KHP is a little moist, so when mass was used to determine the moles of KHP, a higher number of moles than what is actually present would be obtained (because some of that mass was not KHP but it was assumed to be so. Therefore, there is actually a less present number of moles than the certain number that was thought of.

During the titration, NaOH reacts in a 1:1 ratio with KHP. So it was determined that there was the same number of moles of NaOH was the volume used as there were KHP in the mass that was weighed out. Since there was an overestimation in the moles of KHP, then there also would be an overestimation in the number of moles of NaOH.

Thus, NaOH will appear at a higher concentration than it actually is.

7 0

3 years ago

Which have more molecules ? 20 g of ammonia or 30 g of oxygen gas?

hodyreva [135]

I think it's oxygen gas

5 0

2 years ago

23g of sodium reacted with 35.5g og chlorine calculate the mass of the sodium chloride formed. Help!

Simora [160]

Hope this helps you.

4 0

3 years ago

How much energy is required to melt 10. 0 g of ice at 0. 0°C, warm it to 100. 0°c and completely vaporize the sample?

natta225 [31]

The 7160 cal energy is required to melt 10. 0 g of ice at 0. 0°C, warm it to 100. 0°C and completely vaporize the sample.

Calculation,

Given data,

Mass of the ice = 10 g

Temperature of ice = 0. 0°C

The ice at 0. 0°C is to be converted into water at 0. 0°C

Heat required at this stage = mas of the ice ×latent heat of fusion of ice

Heat required at this stage = 10 g×80 = 800 cal

The temperature of the water is to be increased from 0. 0°C to 100. 0°C

Heat required for this = mass of the ice×rise in temperature×specific heat of water

Heat required for this = 10 g×100× 1 = 1000 cal

This water at 100. 0°C is to be converted into vapor.

Heat required for this = Mass of water× latent heat

Heat required for this = 10g ×536 =5360 cal

Total energy or heat required = sum of all heat = 800 +1000+ 5360 = 7160 cal

to learn more about energy

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6 0

1 year ago