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3 years ago

Why didn't mendeleev use atomic number to arrange the elements?

1 answer:

8 0

The primary reason for this was that Mendeleev didn't know that atomic numbers actually existed. Atomic numbers were only discovered a period after Mendeleev's time. The use of X-rays made it possible to find the atomic number, and those had not been discovered yet. 
The periodic table was then arranged in 1913 by Henry Moseley in an arrangement according to atomic number.

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What is the nuclear charge of a berrylium atom?

ICE Princess25 [194]

Answer:

The charge on the nucleus of an atom; controlled by the number of protons and electrons present in an atom.

Explanation:

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3 years ago

How could you ensure that all the spectroscopes used the same calibration line and equation? What would you need to be sure was

NISA [10]

People had asked this many times and that is why they came up with methods and standards that will answer these type of questions. You can look it up in the NIST or the National Institute for Standards and Technology.

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3 years ago

How many moles of oxygen must be placed

umka21 [38]

Answer: 0.245 moles of oxygen must be placed in the container to exert the given pressure at the given temperature. The Ideal Gas Law equation gives the relationship among the pressure, volume, temperature, and moles of gas.

Further Explanation:

The Ideal Gas Equation is:

$PV = nRT$

where:

P - pressure (in atm)

V - volume (in L)

n - amount of gas (in moles)

R - universal gas constant $0.08206 \frac{L-atm}{mol-K}$

T - temperature (in K)

In the problem, we are given the values:

P = 2.00 atm (3 significant figures)

V = 3.00 L (3 significant figures)

n = ?

T = 25.0 degrees Celsius (3 significant figures)

We need to convert the temperature to Kelvin before we can use the Ideal Gas Equation. The formula to convert from degree Celsius to Kelvin is:

$Temperature \ in \ Kelvin = Temperature\ in \ Celsius \ + \ 273.15$

Therefore, for this problem,

$Temperature\ in \ K = 25.0 +273.15\\Temperature\ in \ K = 298.15$

Solving for n using the Ideal Gas Equation:

$n \ = \frac{PV}{RT}\\n \ = \frac{(2.00 \ atm) \ (3.00 \ L)}{(0.08206 \ \frac{L-atm}{mol-K})( 298.15 \ K)} \\n \ = 0.245 \ mol$

The least number of significant figures is 3, therefore, the final answer must have only 3 significant figures.

Learn More

1. Learn more about Boyle's Law brainly.com/question/1437490

2. Learn more about Charles' Law brainly.com/question/1421697

3. Learn more about Gay-Lussac's Law brainly.com/question/6534668

Keywords: Ideal Gas Law, Volume, Pressure

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3 years ago

A cubic meter is about the same as the volume occupied by a _____. basketball arena kilogram of water washing machine cup of mil

Zinaida [17]

washing machine, hopefully this helps

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3 years ago

A drought is best defined as

Lapatulllka [165]

A drought is a period of drier-than-normal conditions that results in water-related problems. When rainfall is less than normal for several weeks, months, or years, the flow of streams and rivers declines, water levels in lakes and reservoirs fall, and the depth to water in wells increases.

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3 years ago