Why did mendeleev leave blank spaces in his version of the periodic table?.

Answers

Answer 1
Answer: He left blank spaces for undiscovered elements to be added to the table.

Explanation:

Answer 2

Answer:

Mendeleev left blank spaces in his version of the periodic table because he left the gaps to place elements not known at the time


Related Questions

Zac releases the air from a balloon. Which statement best describes what will happen to the air that was inside the
balloon?
O It will become more compacted.
O will remain the shape of the balloon but not the size.
O It will remain the size of the balloon but not the shape.
It will expand to fill the room.

Answers

Answer: It will expand to fill the room.

Explanation:

Gases will expand or compact to fill the available space.

A 5 Complete the sentences using words from the list. You may use them once, more than once, or not at all.
increases;decreases;stays the same
a) When liquid water boils, the distance between the particles ____
b) When liquid water boils, the strength of the attractive forces between the particles ___
c) When steam condenses, the speed of movement of the particles ___​

Answers

Answer

Number 1. increase

number 2 . decrease

number 3. decrease

How many grams of
diphosphorus trioxide, P2O3, are
required to react completely with
2.25 moles H₂O?

P2O3 + 3H₂O → 2H3PO3

[?] g P₂03

Answers

From the coefficients of the equation, we know that for every 3 moles of water consumed, 1 mole of diphosphorus trioxide is consumed.

This means we need to find the mass of 0.75 moles of diphosphorus trioxide.

The atomic mass of phosphorous is 30.973761998 g/mol.The atomic mass of oxygen is 15.9994 g/mol.

So, the formula mass of diphosphorus trioxide is:

2(30.973761998)+3(15.9994)=109.945723996 g/mol.

Thus, 0.75 moles have a mass of:

0.75(109.945723996), which is about 82.5 g (to 3 sf)
the answer is 82.5 g P2O3

you can use stoichiometry to solve for this problem. you’re given 2.25 mol H2O and when you look at your chemical reaction, you can see there’s 3 moles of H2O (look at the coefficients) and do the mole ratio. so in the chemical reaction, there’s 1 mol P2O3 and 3 mol H2O. you get your moles with that and since you need it in grams, you need to convert it using the P2O3 molar mass.

. What is the relationship between the speed of impact and the dropping height?

Answers

The relation between the speed of impact and the dropping height is

[tex]\rm h =\dfrac{1}{2g}v^2[/tex]

What is Speed of Impact ?

It is defined as the speed of an object when it falls from a height  and makes an impact with the ground or any other object.

As the object is falling from the height , its velocity will be continuously changing

Assuming it has no initial velocity , u = 0

let the final velocity is  [tex]\rm v_f[/tex] = [tex]\rm \sqrt {2gh}[/tex]

the potential energy at the height  h as  mgh

the kinetic energy when it reaches the bottom as  [tex]\rm \dfrac{1}{2}mv^2[/tex]

As the energy is always conserved

 [tex]\rm mgh = \dfrac{1}{2}mv^2[/tex]

[tex]\rm h =\dfrac{1}{2g}v^2[/tex]

This is the relation between the speed of impact and the dropping height.

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the physical matter of which living or non living things are composed is called a

Answers

The physical matter of which living or non living things are composed is called a molecule

What is a molecule?

A molecule is the smallest particle of an element or a compound which can normally exist alone and still retain the properties of that substance.

A molecule could be made up of an atom of an element of different atoms of elements such as:

HydrogenOxygenCarbonSodiumPotassiumMagnesium

So therefore, the physical matter of which living or non living things are composed is called a molecule.

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Look at pic and help

Answers

Answer:

Answer

Explanation:

1) Other gasses / or argon (based on what u took in ur school )

2) oxygen

3? Nitrogen

Answer:

By volume, the dry air (which i'm assuming that's what either the blue or red is) in Earth's atmosphere is about 78.09 percent nitrogen, and 0.93 percent argon (which might be what red is (if the red isn't dry air)). A brew of trace gases accounts for the other 0.03 percent (which I think that might be the yellow), including the greenhouse gases carbon dioxide, methane, nitrous oxide and ozone.

Explanation:

What mass of reactants are used
during the reaction?
Iron + Sulfur➜ Iron Sulfide
27.50 g
? g
Give your answer to the correct number of
significant figures.
(g) Iron + Sulfur

Answers

Answer:

27.50 g

Explanation:

Unless weight was somehow gained/lost during the reaction, the products should weigh as much as the reactants. Since this isn't specified the mass of the reactants should be equal to the mass of the products.

Which atomic models(Bohr, Thomson, Rutherford, Dalton) in task 1 are not supported by Thomson’s experimental evidence? For each of these models, explain the experimental results that the model would predict.

Answers

Rutherford model task 1 is not supported by Thomson’s experimental evidence.

What is an atom?

The atom consists of matter that may be split without releasing electrical charges.

It's also the smallest unit of matter with chemical element features. As a result, the atom is the fundamental unit of science.

The nuclear model of the atom was initially put out by Rutherford. His atomic model states that the majority of an atom's volume is empty,

The nucleus, which contains protons and neutrons, is located in the middle of the atom, and its electrons orbit the nucleus in well-defined paths.

If we discuss the research of some other scientists, like Dalton, Neil Bohr, and JJ Thomson, they are all mostly consistent with Rutherford's findings.

For instance, Dalton's atomic theory presupposed that all atoms are roughly the same size and that atoms interact to generate compounds.

According to Rutherford's theory, atoms have a fixed number of electrons that can be shared to create compounds.

The Bohr model, which posits that electrons orbit the nucleus in certain shells, is also consistent with Rutherford's findings, which gave rise to the idea of shells.

If we discuss Thomson's Plum Pudding Model, it describes atoms as negatively charged particles around a soup of positively charged ions. This is also consistent with Rutherford's findings, which show that positive nuclei are surrounded by negative electrons.

Although Rutherford's model was the greatest atomic model, it nevertheless drew on several earlier investigations and was therefore consistent with the outcomes of earlier models.

Hence rutherford model task 1 is not supported by Thomson’s experimental evidence.

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There are two common oxides of copper; one is 80% copper and the other is 89% copper by weight. Calculate the formula and name each compound.

Answers

80% copper (Cu)

Cu: 80 :  63.546 = 1.259

O: 20 : 16 = 1.25

Cu:O = 1 : 1

the formula: CuO

89% copper (Cu)

Cu: 89 :  63.546 = 1.4

O: 11 : 16 = 0.6875

Cu:O = 2:1

the formula: Cu₂O

What is surface tension? Describe how surface tension in water is useful for plants and animals.
This is not multiple choice, I need help please :')

Answers

It is a tension created by the attraction of molecules to the surface by the molecules in a bulk of a solution.

The attraction force present between water molecules is cohesion force.

The phenomenon of surface tension provides two major characteristics to the water:

 It makes the surface molecules to be held together  Responsible for formation of water droplet

Plants take water from soil using it's roots , and water is travelling through the xylene tissues present in a plant , so the cohesion forces present in water helps it to travel to the higher places in plants.

While in case of animals, this attraction forces increases the surface density which helps to insects to walk on to the water surface.

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if i poured green solution into another test tube and added some copper pieces to the solution will a displacment action occur

Answers

Depends on what kind of ions are present in the green solution

Explanation:

Cr3+, a famous green ion can obviously be displayed by a Cu2+ ion

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What is a quantum of light energy called?
O A. A photon
OB. A frequency
O C. A proton
O D. An electron

Answers

Answer:

A) photon

Explanation:

hope it helps and give brainliest if its correct

Answer:

Photon

Explanation:

please mark brainliest please

A scientist measures the standard enthalpy change for the following reaction to be -139.5 kj :

h2(g) + c2h4(g)c2h6(g)

based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of formation of c2h4(g) is _____ kj/mol.

Answers

Answer:

A scientist measures the standard enthalpy change for the following reaction to be -139.5 kj :

h2(g) + c2h4(g)c2h6(g)

based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of formation of c2h4(g) is _____ kj/mol

Explanation:

Hydrogen ΔHof (kJ/mol) ΔGof (kJ/mol) So (J/mol K)

H2 (g)

0

0

130.7

Carbon ΔHof (kJ/mol) ΔGof (kJ/mol) So (J/mol K)

C2H6 (g)

-84.7

-32.8

229.6

The energy produced by the snack in an experiment is calculated to be 41,800 J/g. What is the energy of the snack in Calories/
gram?

snack energy = [?] Cal/g or kcal/g

remember there are 4.18J per 1 calorie

Answers

The energy of the snack in calories per gram is 9983.3 Calories/gram.

What is the energy of a snack?

The energy that is contained in a snack is obtained from a calorimeter when the snack is burnt in a calorimeter. The mass of the snack that is burnt is measured in terms of energy output of the calorimeter.

If  1 calorie = 4.18J

x calorie = 41,800 J

x = 41,800 J * 1 calorie/4.18J

x = 9983.3 Calories/gram

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Calculate the percent covalent character of a chemical bond between iodine and lithium.

Answers

Answer:

27966692

Explanation:

I don't know if this is right or not

The liquids having same boiling point cannot be seperated from its mixture by distillation, why?​

Answers

Answer:

Explanation:

They cannot be separated by distillation since it depends on a liquid's ability to boil at a certain temperature. If you have two liquids with the same boiling temperatures, the proportion of each in the vapor phase will be about equal, making it impossible to separate them. Although they presumably do not have the same freezing point, you might use a different method like chromatography or work with their freezing points instead. You could then selectively crystallize one component while leaving the other as a pure liquid.

____________

Definitions:

Distillation:

#1: The volatilization or evaporation and subsequent condensation of a liquid, as when water is boiled in a retort and then the steam is condensed in a cool receiver.

Answer:

Because different compounds often have different boiling points, the components often separate from a mixture when the mixture is distilled. The boiling point is the temperature at which the vapor pressure of the liquid phase of a compound equals the external pressure acting on the surface of the liquid.

Explanation:

How many moles of LiCl will I have if I start off with .425 moles of CaC12?

Answers

LiOH+CaCl_2—»LiCl+Ca(OH)_2

Balanced

Moles of CaCl_2=0.425mol

1 mol CaCl_2 producees 1 mol LiCl

Moles of LiCl

0.425(1)0.425moles

The equation is

[tex]\\ \tt{:}\dashrightarrow LiOH+CalCl_2\longrightarrow LiCl+Ca(OH)_2[/tex]

This is balanced

1mol of LiCl needs 1 mol CaCl_2

Then

0.425mol of CaCl_2 will produce 0.425mol LiCl

Which of the following most accurately describes a regulatory molecule that must be transported to its place of action within the body?

hormone

polypeptide

enzyme

Answers

Answer:

the answer is hormone

Explanation:

because it is

PLEASE HELP FAST! How many grams of NO are formed if 8.3 g of ammonia react with 11.8 g of oxygen? The reaction is 4NH3 + 5O2 --> 4NO + 6H2O.

Options:
A. 8.85 g NO
B. 12.6 g NO
C. 14.6 g NO
D. 9.3 g NO

Answers

The mass of NO produced is 9.3 g; option D.

What mass of NO is produced from the reaction?

The mass of nitrogen (ii) oxide, NO, produced from the reaction is determined from the mole ratio of the reaction.

The mole ratio of ammonia to oxygen from the equation of the reaction is 4 : 5.

moles of oxygen = 11.8/32 = 0.368

moles of ammonia = 8.3/17 = 0.488

Oxygen is the limiting reactant.

Mass of NO produced = 0.369 * 4/5 * 30 = 9.4 g NO

In conclusion, approximately 9.3 g of NO is produced.

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the aria ""batter my heart"" from doctor atomic has musical influences from which era?

Answers

The aria ""batter my heart"" from doctor atomic has musical influences from the era of Renaissance.

Why is batter my heart attributed to  to Renaissance era?

The Renaissance era can be regarded as the era around 14th century and batter my heart was produced around the 13/14th century.

The batter my heart was among the Sicilian school of court poets, that was very famous which  emphasizing the importance of the heart.

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what is the approximate partial pressure of oxygen at 1500 m?

Answers

The approximate partial pressure of oxygen at 1500 m is 0.18 atm.

Pressure of the air

From barometric pressure table;

1500 m = 85 kPa

1 kPa = 0.0099 atm

85 kPa = ?

= 0.84 atm

Oxygen percentage in air  = 21%

Partial pressure of oxygen in air

P = 0.21 x P(total)

P = 0.21 x 0.84 atm

P = 0.18 atm

Thus, the approximate partial pressure of oxygen at 1500 m is 0.18 atm.

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The cutoff frequency for a certain element is 1.22 x 1015 Hz. What is its work function in eV?
Hint: 1 eV 1.60 x 10-19 J
=[?] eV

someone please teach me how to solve this its gonna make me cry

Answers

The work function of the metal is obtained as 5.1 eV

What is the cutoff frequency?

The cutoff frequency is the frequency below which photo electric effect can not occur as electrons are not removed from the metal surface.

Now;

fo = 1.22 x 10^15 Hz

Wo = hfo

Wo = 6.6 * 10^-34 * 1.22 x 10^15

Wo = 8.1 * 10^-19 J

If 1 eV = 1.60 x 10-19 J

x eV = 8.1 * 10^-19 J

x = 8.1 * 10^-19/ 1.60 x 10-19

x = 5.1 eV

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Up late, a tired engineer calculated the molar mass of nitroglycerin (C3H5N3O9) to be 193.7 g/mol, but this incorrect. What is the percent error of this incorrect molar mass

Answers

The atomic mass of carbon is 12.011 g/mol.The atomic mass of hydrogen is 1.00794 g/mol.The atomic mass of nitrogen is 14.0007 g/mol.The atomic mass of oxygen is g/mol.

So, the formula mass of nitroglycerin is[tex]3(12.011)+5(1.00794)+3(14.0007)+9(15.9994)=227.0694 \text{ g/mol}}[/tex]

Therefore, the percent error is

[tex]\frac{193.7-227.0694}{227.0694} \times 100=\boxed{-14.70 \% \text{ (to 4 sf)}}[/tex]

What type of molecule is pentanal?
o a. aldehyde
o b. ester
o c. ketone
o d. alcohol

Answers

Answer:

aldehyde

Explanation:

it ends with "al" of "al"dehyde, always check the end

Mr. Auric Goldfinger, criminal mastermind, intends to smuggle several tons of gold across international borders by disguising it as lumps of iron ore. He commands his engineer minions to form the gold into little spheres with a diameter of exactly
8 cm and paint them black.

However, his chief engineer points out that customs officials will surely notice the unusual weight of the "iron ore" if the balls are made of solid gold (density
). She suggests forming the gold into hollow balls instead , so that the fake "iron ore" has the same density as real iron ore
One of the balls of fake "iron ore," sliced in half.

Calculate the required thickness of the walls of each hollow lump of "iron ore." Be sure your answer has a unit symbol, if necessary, and round it to 2
significant digits.

Answers

The thickness of the walls of each hollow lump of iron ore is: 0.295cm. This is determined using the knowledge of the Volume of a Hollow Sphere.

What is the Volume of a Hollow Sphere?

The formula for the Volume of a Hollow Sphere is give as:

Volume of a Hollow = 4/3 R³ – 4/3 r³

Step 1 - Find the apparent volume of 8cm diameter sphere including the wall the the hollow inside

V = 4/3 r³

V = (4/3) (8)³

V = (4/3) * (22/7) * 512

V = 2145.52cm³

Step 2 - Determine the mass of Gold required for the sphere to achieve the density of iron ore if the apparent volume is as given in Step 1 above.

Recall that Mass = Density * Volume

Mass = 5.15 *  2145.52

Mass = 11049.45

Step 3 - Find volume of gold based on mass calculated in Step 2 above

Recall that :

Volume = Mass/Density

Thus,

V = 11049.4/19.3

Thus, Volume = 572.51cm³

Step 4 - Find the width of the wall of a hollow sphere for the volume realized in step 3

Recall the initial formula:

Volume of a Hollow = 4/3 R³ – 4/3 r³

Thus, 572.51 = (4/3) (8³ - (8 - t)³)

572.51 = (4/3) *(22.7) *(8³ - (8 - t)³)

572.51 = (88/21) *(8³ - (8 - t)³)

Multiply both sides by 21 and we have

88 (512 - (8 - t)³) = 12,022.71

Simplify further
(8 - t)³ = 357.38

t = 0.9035cm

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There are 8.421 g of dry ZnSO4 and
6.579 g H₂O in the sample.

Step 2: Determine the moles of water and anhydrous compound.

Zn = 65.38 g/mol, S = 32.07 g/mol,
H = 1.01 g/mol, O = 16.00 g/mol

How many moles of ZnSO4 are present?

[?] mol ZnSO4

Answers

The number of moles of H₂O is  0.36 mol.

The number of moles of LiClO₄ is  0.0521  mol.

What are moles?

Mole is an important standard unit used for the measurement of large quantities of atoms, molecules, or other particles. One mole is equal to 6.022×10²³ units.

The number of moles of a substance is calculated by:

Moles =[tex]\frac{mass}{molar \;mass}[/tex]

To find the number of moles of H₂O:

Mass of H₂O in the sample = 6.579 g

The molecular weight of H₂O = 18.02g

Moles = [tex]\frac{mass}{molar \;mass}[/tex]

Moles = [tex]\frac{6.579 g}{18.02g}[/tex]

Moles = 0.36

To find the number of moles of [tex]ZnSO_4[/tex]:

Mass of [tex]ZnSO_4[/tex] in the sample = 8.421 g

The molecular weight of [tex]ZnSO_4[/tex]= 161.47 g/mol

Moles =[tex]\frac{mass}{molar \;mass}[/tex]

Moles = [tex]\frac{8.421 g}{161.47 g/mol}[/tex]

Moles = 0.0521 moles

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Silver has the density of 9.32 g/cm^3. Find the length of one side of a 184 g silver cube. Assume now that the silver cube above was melted and reshaped into a sphere. Find the sphere’s diameter

Answers

s = 2.70cm
d = 3.35cm

Which industrial methods of preparing alcohol are more economical? Explain.​

Answers

The industrial methods of preparing alcohol that is more economical is fermentation.

What is fermentation?

Fermentation is defined as the industrial method by which starch is converted to ethyl alcohol by using some specific enzymes and microorganisms known as yeast

It is an economical method because the raw material which is starch is readily available.

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Consider the compound calcium nitrate, Ca(NO3)2. Which statements are true about this compound? Check all that apply. There are two atoms of oxygen. There are six atoms of oxygen. There are two nitrogen atoms. There are two calcium atoms.

Answers

Calcium nitrate is made up of 6 oxygen atoms, 2 nitrogen atoms and one calcium atom.

Ca(NO₃)₂

Calcium nitrate is a compound consisting of calcium, nitrogen and oxygen compoundsIt is an inorganic compoundIt is water-absorbent and absorbs moisture from airCalcium nitrate has two forms, hydrous and anhydrousBoth forms are colourless and odourlessThe reaction to form Calcium nitrate is Ca + 2NO₃ -----> Ca(NO₃)₂

The number of oxygen atoms is: 2x3 = 6The number of nitrogen atoms is: 2x1= 1There is 1 calcium atom

Thus, calcium nitrate is made up of 6 oxygen atoms, 2 nitrogen atoms and one calcium atom.

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Answer:

B)There are six atoms of oxygen.

C)There are two nitrogen atoms.

Explanation:

edge 2023

Dalton law states that the partial pressure of a gas in a mixture of gases is _____ to the total pressure of the mixture.

Answers

Answer:

Dalton law states that the partial pressure of a gas in a mixture of gases is equal to the total pressure of the mixture.

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