Question 13 (1 point)

Demócrito, Dalton, Thompson, Rutherford y Bohr aportaciones y postulados de los científicos de la composición y estructura del á

gregori [183]

Answer:

Niels Bohr proposed a model of the atom in which the electron was able to occupy only certain orbits around the nucleus. This atomic model was the first to use quantum theory, in that the electrons were limited to specific orbits around the nucleus.

Ernest Rutherford is known for his pioneering studies of radioactivity and the atom. He discovered that there are two types of radiation, alpha and beta particles, coming from uranium. He found that the atom consists mostly of empty space, with its mass concentrated in a central positively charged nucleus.

On April 30, 1897, British physicist J.J. Thomson announced his discovery that atoms were made up of smaller components. This finding revolutionized the way scientists thought about the atom and had major ramifications for the field of physics.

What is Dalton's atomic theory?

A theory of chemical combination, first stated by John Dalton in 1803. It involves the following postulates: (1) Elements consist of indivisible small particles (atoms). (2) All atoms of the same element are identical; different elements have different types of atom. (3) Atoms can neither be created nor destroyed.

The theory of Democritus held that everything is composed of "atoms," which are physically, but not geometrically, indivisible; that between atoms, there lies empty space; that atoms are indestructible, and have always been and always will be in motion; that there is an infinite number of atoms and of kinds of atoms,

Explanation:

7 0

3 years ago

How to find how many electrons are in an element

Murljashka [212]

Explanation:

1) Locate the atomic number in the upper left corner of the square. The atomic number will tell you the number of protons

2) In a neutral state, the element will contain the same number of protons as it will electrons.

--> Boron (B) has an atomic number of 5, so it has 5 protons.

--> Having 5 protons (+1 charge each) means to be balanced, it must have 5 electrons (-1 charge each)

However, what if it's not in a neutral state?

If it's not in a neutral state, it will look something like this:

Ca ^ 2+

<em>Btw, the "^" means that it will be written like it's an exponent. That confuses people sometimes.</em>

Anyways, the "2+" means it's an ion with a positive charge of 2. For us to have a positive charge, it means it's lost two electrons (cause electrons are negative, so taking them away means we are left with a more positive charge).

To get the number of remaining electrons, subtract the 2 from the atomic mass. In this case, that would be 20.

20 - 2 = 18 electrons

Another example:

N ^3-

Atomic Number: 7

7 + 3 = 10 electrons.

Why did I add here instead of subtracting? It's cause the 3- means we have added electrons, resulting in the ion having a negative charge. It's got more electrons than usual.

Hopefully this helps a bit.

5 0

3 years ago

When the equation Sn + HNO₃ → SnO₂ + NO₂ + H₂O is balanced in acidic solution, what is the smallest whole-number coefficient for

balu736 [363]

Answer:

1.

Explanation:

Hello,

In this case, for the given reaction we first assign the oxidation state for each species:

$Sn^0 + H^+N^{5+}O^{-2}_3 \rightarrow Sn^{4+}O_2 + N^{4+}O^{2-}_2 + H^+_2O^-$

Whereas the half reactions are:

$Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-\\\\H^++H^+N^{5+}O^{-2}_3 +1e^-\rightarrow N^{4+}O^{2-}_2+H_2O$

Next, we exchange the transferred electrons:

$1\times(Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-)\\\\4\times (H^++H^+N^{5+}O^{-2}_3 +1e^-\rightarrow N^{4+}O^{2-}_2+H_2O)\\\\\\Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-\\\\4H^++4H^+N^{5+}O^{-2}_3 +4e^-\rightarrow 4N^{4+}O^{2-}_2+4H_2O$