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Henry Moseley used X-ray experiments to determine the atomic number of elements. How did his discovery contribute to the develop

sesenic [268]

Here we have to chose the correct statement which affect the discovery of the atomic number on the periodic table.

The discovery of the atomic number of the elements: C. It allowed the elements to be placed in strict order of increasing atomic number.

The use of X-ray determined the atomic number or number of electrons present in an element. The number of electrons is the basis of generate the periodic table, where the elements are arranged in terms of the number of electrons present in the atom in early stage of periodic table.

However in later the modern periodic table generated, which has group and period in terms of their property. Although the strictness on the increasing number of electrons are followed.

8 0

3 years ago

Compare and contrast the atomic structures of helium and lithium at room temperature

kykrilka [37]

Answer:

How is it possible that helium, having 2 protons, and lithium, having 3 protons, are so different in terms of their physical properties? How come one is a gas at room temperature and the other is a solid metal?

Then why lithium and beryllium, the latter having 1 proton more than the former, are both metals and solids at room temperature?

Now if you remove neutrons from the nuclei of any element (except hydrogen), they form isotopes that have similar chemical properties and different physical properties, while still being an atom of the same element - therefore the protons, if I understand it correctly, are what determine whether an element is a gas or a solid at room temperature, and not the neutrons (or even electrons). Is this true?

The deeper question is that why do the properties of elements and their atoms change significantly - in some cases as with helium and lithium - just by having an additional proton in their nucleus, if the fundamental building blocks of protons (quarks) are identical for each proton? Then in the case of lithium and beryllium, why is the change in physical properties so subtle compared to the first case?

Edit

This question has already been asked before, however I am specifically interested in helium and lithium - why is one a gas and the other a solid metal at room temperature, having completely different chemical and physical properties? Is this a result of the electron shell configuration? Why does an extra proton, neutron and electron give rise to such a difference?

6 0

3 years ago

What is the Percent yield made if 3.9 grams of a substance were made experimentally while you calculated 3.6 grams of substance

son4ous [18]

Answer:

108.3%

Explanation:

Percent yield is the concept where you calculate the ratio or percent of actual yield to theoretical yield.

Actual yield is what you actually experimentally got.

Theoretical yield is what you expected to get from math.

Always remember the two terms above will never be same in real life because we do not have perfect system where we can account for energy loss and such in daily life.

Percent yield= actual yield/theoretical yield x 100%

= 3.9/3.6 x 100%

= 108.3%

Percent yields are understandably less than 100% because of the reasons indicated earlier like imperfect systems. However, percent yields greater than 100% are possible, such as our question, if the measured product of the reaction contains impurities that cause its mass to be greater than it actually would be if the product was pure.

8 0

3 years ago

What ALWAYS occurs simultaneously with reduction?

Lena [83]

Answer:

Oxidation occurs simultaneously with reduction.

4 0

3 years ago

Read 2 more answers

In a neutralization reaction 30.0mL of 0.234M KOH solution is reacted with 30.0mL of 0.234M HNO3 solution and a temperature rise

iris [78.8K]

Based on the data provided, the equation of the reaction is:

$KOH + HNO_3 \rightarrow KCl + H_2O$
moles of water produced = 0.00702 moles
Heat produced = 1404.48 J
Enthalpy of neutralization = 200 kJ/mol

<h3>What is enthalpy of neutralization?</h3>

Enthalpy of neutralization is the heat change when one mole of hydrogen ions from an acid reacts with one mole of hydroxide ions from an alkali to produce one mole of water.

The equation of the reaction of KOH and HNO3 is given below:

$KOH + HNO_3 \rightarrow KCl + H_2O$

1 mole of KOH reacts with 1 mole of HNO3 to produce 1 mole of water.

Volume of KOH = 30 mL = 0.03 L

moles of KOH = 0.03 × 0.234 = 0.00702 moles

Therefore, 0.00702 moles of water are produced

Heat produce = mass × specific heat × temperature difference

Volume of solution = 60 mL

density of solution = 1.0 g/mL

mass of solution = 60 mL × 1.0 g/mL = 60 g

Heat produced = 60 × 4.18 × 5.6

Heat produced = 1404.48 J

Enthalpy of neutralization = 1404.48 J/0.00702 moles

Enthalpy of neutralization = 200068.37 J/mol

Enthalpy of neutralization = 200 kJ/mol

Learn more about enthalpy of neutralization at: brainly.com/question/24939435

5 0

3 years ago

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