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Masja [62]
3 years ago
13

When was the idea of an atom first developed? Describe this theory.

Chemistry
1 answer:
malfutka [58]3 years ago
7 0

The existence of an atom was first suggested by Democritus, the idea is then developed in 1803 by John Dalton.

According to Dalton's atomic theory, matter is made up of atoms which are inseparable and can not be destroyed further. For a given element, all atoms have identical mass and properties. Atoms of two different elements combine to form compounds and rearrangement of these atoms results in chemical reaction.


You might be interested in
Determine The Oxidation Number for
bixtya [17]

Answer:

A is +4

B is +4

C is +6

D is +3

E is +4

Explanation:

In order to learn how to find the oxidation number of an atom in a given compound, it is important to learn what oxidation numbers are. The oxidation number of an atom is a number that represents the total number of electrons lost or gained by it.

Calculating Oxidation Numbers

An oxidation number can be assigned to a given element or compound by following the following rules.

Any free element has an oxidation number equal to zero.

For monoatomic ions, the oxidation number always has the same value as the net charge corresponding to the ion.

The hydrogen atom (H) exhibits an oxidation state of +1. However, when bonded with an element with less electronegativity than it, it exhibits an oxidation number of -1.

Oxygen has an oxidation of -2 in most of its compounds. However, in the case of peroxides, the oxidation number corresponding to oxygen is -1.

All alkali metals (group 1 elements) have an oxidation state of +1 in their compounds.

All alkaline earth metals (group 2 elements) exhibit an oxidation state of +2 in their compounds.

In the compounds made up of two elements, a halogen (group 17 elements) have an oxidation number of -1 assigned to them.

In the case of neutral compounds, the sum of all the oxidation numbers of the constituent atoms totals to zero.

When polyatomic ions are considered, the sum of all the oxidation numbers of the atoms that constitute them equals the net charge of the polyatomic ion.

Thus, the oxidation number of an atom in a given compound can be calculated with the steps mentioned above.

How to Calculate Oxidation Number

.

Hydrochloric Acid (HCl)

As per the rules discussed above, the oxidation state of a group 17 element (halogen) in a diatomic molecule is -1. It is also discussed that hydrogen always exhibits an oxidation number of +1 unless it is paired with a less electronegative element.

Since chlorine is more electronegative than hydrogen, an oxidation number of +1 can be assigned to the hydrogen atom in HCl.

Therefore, the oxidation number of hydrogen is +1 and the oxidation of chlorine is -1 in HCl. These values can be verified by adding these oxidation numbers. Since the total is zero, which is the value of the oxidation number corresponding to a neutral molecule, the values are verified.

Carbon Dioxide (CO2)

According to the rules to calculate oxidation number, which can be found in the previous subsection, the oxidation number of oxygen in its compounds (excluding peroxides) is -2.

Since there are two oxygen atoms in carbon dioxide, the total of the oxidation numbers corresponding to each oxygen is -4.

Since the CO2 molecule is neutral, the carbon atom must exhibit an oxidation state of +4 (the sum of all the oxidation numbers in a neutral molecule is zero).

Therefore, the oxidation state of oxygen was found to be -2 and the oxidation number of carbon is +4 in a carbon dioxide molecule.

7 0
2 years ago
Methane and hydrogen sulfide form when hydrogen reacts with carbon disulfide. Identify the excess reagent and calculate how much
Leno4ka [110]

Answer:

There will be produced 9L of CH4 and 18 L of H2S. There will remain 3 L of CS2

Explanation:

Step 1: Data given

volume of H2 = 36.00 L

volume of CS2 = 12 L

Step 2 = the balanced equation

4H2(g) + CS2(g) → CH4(g) + 2H2S(g)

Step 3: Calculate number of moles of H2

1 mol = 22.4 L

36 L = 1.607 mol

Step 4: Calculate moles of CS2

1 mol = 22.4 L

12 L = 0.5357 moles

Step 5: Calculate the limiting reactant

For 4 moles of H2 we need 1 mol of CS2 to produce 1 mol of CH4 and 2 moles of H2S

H2 is the limiting reactant. It will completely be consumed. ( 1.607 moles)

CS2 is in excess. There will react 1.607/4 = 0.40175 moles

There will remain 0.5357 - 0.40175 = 0.13395 moles of CS2

0.13395 moles of CS2 = 3 L

Step 6: Calculate products

For 4 moles of H2 we need 1 mol of CS2 to produce 1 mol of CH4 and 2 moles of H2S

For 1.607 moles of H2 we'll have 0.40175 moles of CH4 (= 9L) and 0.8035 moles of H2S =(18L)

There will be produced 9L of CH4 and 18 L of H2S. There will remain 3 L of CS2

8 0
3 years ago
Using the picture below, compare and contrast the plant cell and the animal cell (What do they have different? What do they have
STALIN [3.7K]

Answer:

Animal cell lacks chloroplasts and a cell wall

Explanation:

Unlike animal cells, plant cells have chloroplasts and a cell wall. In a plant cell, the chloroplasts work to use photosynthesis in order to turn light into energy for the plant cell. Animal cells do not utilize light energy, and therefore do not carry out photosynthesis and do not have chloroplasts.

Additionally, the plant cell has a protective cell wall and a cell membrane, while animal cells only have a cell membrane. This is because the plant cells' cell wall provides additional strength and protection against outside factors, such as osmosis.

6 0
3 years ago
A hydrogen-like ion is an ion containing only one electron. The energy of the electron in a hydrogen-like ion is given by:
kupik [55]

hydrogen-like ion is an ion containing only one electron. The energy of the electron in a hydrogen-like ion is given by:

En = −(2.18 × 10^−18J) Z^2 ( 1/n^2 )

where n is the principal quantum number and Z is the atomic number of the element. Plasma is a state of matter consisting of positive gaseous ions and electrons. In the plasma state, a mercury atom could be stripped of its 80 electrons and therefore could exist as Hg80+. Use the equation above to calculate the energy required for the last ionization step.hydrogen-like ion is an ion containing only one electron. The energy of the electron in a hydrogen-like ion is given by:

En = −(2.18 × 10^−18J) Z^2 ( 1/n^2 )

where n is the principal quantum number and Z is the atomic number of the element. Plasma is a state of matter consisting of positive gaseous ions and electrons. In the plasma state, a mercury atom could be stripped of its 80 electrons and therefore could exist as Hg80+. Use the equation above to calculate the energy required for the last ionization step.hydrogen-like ion is an ion containing only one electron. The energy of the electron in a hydrogen-like ion is given by:

En = −(2.18 × 10^−18J) Z^2 ( 1/n^2 )

where n is the principal quantum number and Z is the atomic number of the element. Plasma is a state of matter consisting of positive gaseous ions and electrons. In the plasma state, a mercury atom could be stripped of its 80 electrons and therefore could exist as Hg80+. Use the equation above to calculate the energy required for the last ionization step.

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6 0
2 years ago
Match each body system with its main organ.
olya-2409 [2.1K]

Answer:

it's in the explanation

Explanation:

Lungs- Respiratory

Heart- Circulatory

Brain- Nervous

Stomach- Digestive

Bladder- Excretory

7 0
3 years ago
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