The atomic structure
The structure of an atom is the basic unit of matter
consisting of a nucleus and its negatively charged electron cloud surrounding
it. The nucleus contains a mix of positively charged protons and electrically
neutral neutrons (except in Hydrogen-1 which has no neutrons). The electrons in
an atom bound to the nucleus by the electromagnetic force. Similarly, a
collection of atoms can bind to each other to form a molecule. Atoms containing
the number of protons and electrons of the same neutral, while containing the
number of protons and electrons of different positive or negative and is ion.
Atoms are grouped based on the number of protons and neutrons in the atomic
nucleus. The number of protons in an atom determines the chemical element the
atom, and the number of neutrons determine the isotope of the element.
Kinds of Model Atom
Dalton said that atoms like a solid ball or a ball shot
put JJ.Thomson say that ATOMM like raisin bread E.Rutherford atom like the
solar system suggests
1. John Dalton Atomic Model
In 1808, John Dalton, who is a teacher in the UK,
contemplating on the atom. Results reflection refine Dalton's atomic theory of
Democritus. Shadow Dalton and Democritus is that the atoms of solid shape. In
Dalton argued postulatnya musings about atoms:
1. Each element is composed of extremely small particles
called atoms with
2. Atoms of the same element the same properties
memiliiki
3. Atoms of different elements have different properties
4. Atoms of an element can not be converted into atoms of
another element with the chemical reaction, atoms can not be destroyed and the
atoms also can not be destroyed
5. Atoms can combine to form atoms called molecules
combined
6. In the compound, the mass ratio of each element is
fixed
Dalton's atomic theory began to arouse interest in the
study of atomic models. However, Dalton's atomic theory has shortcomings, which
can not explain a solution to conduct electrical current. How could solid ball
can conduct electricity when electricity is electrons moving. Meaning there are
other particles that can conduct aruslistrik.
2. J.J. Atom Model Thomson
The downside of Dalton repaired by JJ. Thomson,
experiments are done kotoda ray tube. The results of experiments stated there
negatively charged particles called electrons in atoms. A ball of solid surface
surrounded by electrons and other particles that are positively charged atom is
neutral. Thomson model of atom images:
Weakness Thomson models can not explain the arrangement
of positive and negative charges within the atomic sphere.
Weakness Thomson atomic model
Thomson's model can not explain the arrangement of
positive and negative charges within the atomic sphere.
3. Rutherford Atom Model
Rutherford model of the atom
Rutherford conducted a study on α-ray scattering on gold
plates. Observations were developed in the Rutherford atomic model hypothesis.
a. Most of the atom is empty surface.
b. Atom has a positively charged nucleus which is the
center of mass of the atom.
c. Electrons move around the nucleus at a very high
speed.
d. Most of the α particles pass without having distorting
/ barriers. A small portion deflected, and little is reflected.
Weakness Rutherford Atom Model
a. According to the laws of classical physics, electrons
moving around the nucleus emits energy in the form of electromagnetic waves. As
a result, the electron eventually it will run out of energy and eventually
attached to the core.
b. Rutherford atomic model has not been able to explain
where the location of the electron and the way the rotation of the nucleus.
c. Electrons emit energy when moving, so the energy of
the atom becomes unstable.
d. Unable to explain the line spectrum of hydrogen atoms
(H).
4. Niels Bohr Atom Model
Niels Bohr Atom Model
In 1913, Niels Bohr expressed the opinion that the
electrons moving around the nucleus in certain paths called shells. Bohr's
atomic model is a refinement of the atomic model of Rutherford.
Rutherford's atomic theory weaknesses corrected by Neils
Bohr to postulate Bohr:
a. Electrons surrounding the nucleus has a certain
trajectory and energy.
b. In particular orbital, the electron energy is fixed.
The electrons will absorb energy when moving to the outer orbit and will
release energy when moving deeper into orbit
Excess Bohr model of the atom
atom consists of a few skins for a transfer of electrons.
Weakness Bohr model of the atom
a. can not explain the Zeeman effect and the effect
Strack.
b. Unable to explain the events of the chemical bond
well, the influence of magnetic fields on atoms and atomic electron spectrum
more.
QUANTUM NUMBERS
1. The principal quantum number (n): states in which the
electron energy levels are
n has a price of 1, 2, 3, .....
- N = 1 corresponds to the K shell
- N = 2 correspond to the L shell
- N = 3 corresponds to the skin M
- And so on
Each skin or any number of energy levels occupied by
electrons. The number of electrons that can occupy maksimmm energy levels must
satisfy the Pauli formula = 2N2.
Example:
skin-to-4 (n = 4) can be occupied by a maximum = 2 x 42
electrons = 32 electrons
2. Azimuthal quantum number (l): indicate sub skin where
the electron also shows sub skin which is a constituent of skin.
Azimuthal quantum number have prices from 0 to (n-1).
n = 1; l = 0; corresponding K shell
n = 2, l = 0, 1; corresponding L shell
n = 3; l = 0, 1, 2; appropriate skin M
n = 4; l = 0, 1, 2, 3; appropriate skin N
and so on
Sub leather prices vary is given a special name:
l = 0; fit leather sub s (s = sharp)
l = 1; fit leather sub p (p = principle)
l = 2; fit leather sub d (d = diffuse)
Magnetic quantum number (m): ataubeberapa realize that
there is a level of energy in a sub shell. Magnetic quantum number (m) has a
price (-l) to price (+ l).
For:
l = 0 (sub leather s), price m = 0 (having 1 orbital)
l = 1 (p sub shell), price m = -1, O, +1 (have 3
orbitals)
l = 2 (sub skin d), price m = -2, -1, O, +1, +2 (have 5
orbitals)
l = 3 (sub kwit f), price m = -3, -2, O, +1, +2, +3 (has
7 orbitals)
4. Spin quantum number (s): indicates the direction of
rotation of the electron on its axis.
In one orbital, maximum of 2 electrons can circulate and
the two electron spins through the axis in the opposite direction, and each is
priced spin +1 / 2 or -1 / 2.
Aufbau principle
Aufbau principle that electrons fill orbitals starting at
the lowest energy level to a higher energy level.
according to this rule, the order of filling orbitals are
as follows:
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p
The principle of prohibition pauli
Pauli principle states that the ban is not possible in an
atom there are two electrons that are priced the same four quantum biulangan.
Rule hund
According to the rules hund, filling electrons in orbitals of the same energy level, the electrons do not form pairs of electrons before each filled with an electron orbital.
Example:
Example:
24Cr :
4 komentar
Write komentarwhy the Aufbau principle, Aufbau principle that charging electrons in orbitals starting from the lowest energy level to a higher energy level.
Replyaccording to this rule, the order of filling orbitals are as follows:
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p
While it is different from the rule that says that hund filling electrons in orbitals of the same energy level, the electrons do not form pairs of electrons before each filled with an electron orbital. means, rules infringe hund Aufbau principle which states filling electrons in orbitals starting at the lowest energy level to a higher level?
1. Aufbau principle
ReplyThe electrons in an atom subshell trying to occupy low-energy subshell, then go to a higher energy level. Thus, the atomic energy levels are at a minimum. This is called the Aufbau principle. Sequences of energy levels shown in the picture. So, starting orbitals 1s, 2s, 2p, and so on. In the picture we can see that the 3d subshell has a higher energy than the 4s subshell. Therefore, after fully charged 3p next electron will fill the 4s subshell, then it will fill the 3d subshell.
Orbital energy level sequence diagram
2. Hund's Rule
To state the distribution of electrons in the orbitals in a subshell, electron configuration can be written in the form of orbital diagram. An orbital denoted by strip, while the two electrons occupy an orbital denoted by two arrows in opposite directions. If the orbital contains only one electron, written arrows pointing up. In Hund rule, proposed by Friedrich Hund (1894 - 1968) in 1930, mentioned that the electrons in the orbitals of a subshell tend to not pairwise. Newly paired electrons in a subshell if it is no longer empty orbitals.
Orbitals in an atom
Subshell as represented by the strip-owned orbital
actually the Aufbau principle and hund rules no different except that hund fill in the form kofigurasi orbital diagram so he argues that the electron energy levels for all the same and that made the difference just filling.
I think there are some deviations based on the principles of electrical charging afbau with those found by experiment, the electron konsfigurasi Cr and Cu = 24 = 29 electrons konsfigurasi Cr and Cu based on the principles afbau are:
ReplyCr [24]: [Ar] 3d5 4S2
Cu [29]: [Ar] 3d9 4S2
whereas the experimental konsfigurasinya are:
Cr [24]: 3d5 4S1
Cu [29]: 3d10 4S1
konsfigurasi the last two subshell D9 d4 s2 and s2 tend to turn into d5 s1 and s1 D10 turns subshell fully charged (D10) or half full more stable, because the D10 all the electrons are paired and no electro house empty, and the d5 all the electrons have been filled.
mean Aufbau principle states that: "Charging the electron starts from the lowest-energy subshell continued at higher energy subshell". In each sub-shell electrons have limitations that can be filled are:
ReplyS subshell contains a maximum of 2 electrons
P subshell contains a maximum of 6 electrons
D subshell contains a maximum of 10 electrons
Maximum f subshell contains 14 electrons
while the proposed rule hund electrons in the orbital filling rules are:
"Orbitals with the same energy, each filled first by one electron direction (spin) of the same first and then the electrons will enter the orbitals in the order with directions (spin) opposite or in other words all the same subshell orbital each filled with one electron prior to the arrows of the same direction then the rest of the new electron-electron filled as partner with the opposite direction of the arrow ".