ATOMIC STRUCTURE

ATOMIC STRUCTURE
A. BASIC UNDERSTANDING
1. Elementary particles: particles are composed of atoms forming
electron, proton neutron den.
1. Proton: forming atomic particles have the same mass
one sma (amu) and charged +1.
2. Neutron: particles forming a sma atomic mass (amu) and
neutral.
3. Electron: atom forming particles that have no mass and
charged -1.
2. The nucleus: a positively charged nucleus, consisting of protons den
neutrons.
3. Notation elements: z
A A to X: sign atoms (elements)
Z: atomic number = number of electrons
(E)
= Number of protons (p)
A: mass number = number of protons +
neutron
In neutral atoms, applies: the number of electrons = number of protons.
Example:
1. Determine the number of electrons, protons neutrons den of element 26
56 Fe!
Answer:
The number of electrons = number of protons = atomic number = 26
Number of neutrons = mass number - atomic number = 56-26 = 30
2. Give notation elements of X, given the number of neutrons = 14 and
number of electrons = 13!
Answer:
Atomic number = number of electrons = 13
Mass number = number of protons + neutrons = 13 + 14 = 27
So the notation elements: 13
27 X
4. No neutral atoms: electrically charged atoms due to excess or
electron deficiency when compared with the neutral atom.
Positively charged atoms when the electron deficiency, called cations.
Negatively charged atoms when an excess of electrons, called anions.
Example:
- Na +: cation with one electron deficiency
- Mg2-: cation with a shortage of 2 electrons
- Cl-: anion with an excess of one electron
- O2: anion with an excess of two electrons
5. Isotopes: elements of the same atomic number, but different numbers
mass.
Example: oxygen isotopes: 8
16 O: 8
17 O: 8
18 O
6. Isobar: elements of the same mass number, but different numbers
atom.
Example: 27
59 CO with 28
59 Ni
7. Isoton: elements with the same number of neutrons.
Example: 6
13 C with 7
14 N
8. Iso electron: atom / ion with the same number of electrons.
Example: Na + with Mg 2 +
K + with Ar
B. MODEL ATOM
1. MODEL ATOM JOHN DALTON
- Atom is the smallest part of an element
- Atoms can not be created, destroyed, divided, or changed to
other substances
- Atoms of an element is the same in all respects, but different
atoms of other elements
- Chemical reaction is a process of merging or splitting of the atom
elements are visible
Dalton's atomic theory Weakness: can not distinguish sense
den atom molecule. And the atom was not the smallest particles.

ATOM 2.MODEL J.J. THOMPSON
- Atom is a positively charged sphere and inside spread
electrons are like raisins
- The amount of positive charge with a negative charge, so that the atoms are
neutral
3. RUTHERFORD ATOM MODEL
- Atom consists of a very small nucleus with a positive charge
mass is the mass of the atom
- Electrons moving around the nucleus in an atom is
- The number of electrons in an atom equal to the number of protons in the nucleus and
This corresponds to the number
atom
4. MODEL ATOM Bohr
According to Niels Bohr electrons can move (transition) from a lower energy level to a higher energy level or vice versa. Electrons that have the lowest energy, is on the path closest to the nucleus.
The nucleus is positively charged, have an attraction to the negatively charged electrons. As a result, the electrons in each track is always surrounds the nucleus. Electrons are the lowest energy level, most easily drawn by the core.
Danish physicist Neils Bohr called the failures, Rutherford atom through experiments on the hydrogen atom spectrum. His experiment managed to give an overview on the state of the electrons occupy the area around the atomic nucleus. Explanation of Bohr about the hydrogen atom involves a combination of the classical theory of Rutherford and the quantum theory of Planck, to say the four postulates, as follows:
1. There are only a certain set of orbits that are allowed for an electron in a hydrogen atom. Orbit is known as the stationary state of motion (settled) electron and a circular path around the nucleus.
2. As long as the electrons are in a stationary orbit, the electron energy anyway so there is no energy in the form of radiation emitted or absorbed.
3. Electrons can only move from one stationary orbit to another stationary trajectory. In this transition, a certain amount of energy involved, the amount in accordance with Planck equation, ΔE = hv.
4. Stationary trajectory is allowed to have the scale with certain properties, especially property called angular momentum. The magnitude of the angular momentum is a multiple of h/2Π or nh/2Π, where n is an integer and h Planck constant.
According to the Bohr model of the atom, the electrons around the nucleus in certain paths called electron shells or energy levels. The lowest energy level is the electron shell which is located in, getting out of her skin and the greater the number the higher the energy level.

Weaknesses:
This atomic model can not explain the spectrum of colors from many electron atoms.
5. Modern Atomic Theory
Atomic model of quantum mechanics developed by Erwin Schrodinger (1926). Before Erwin Schrodinger, an expert from the German Werner Heisenberg developed the theory of quantum mechanics known as the uncertainty principle is "not possible to set the position and momentum of an object carefully at the same time, which can determined is the probability of finding the electron at a certain distance from the nucleus. "
Region of space around the nucleus with a probability to get the so-called orbital electrons. The shape and orbital energy levels formulated by Erwin Schrodinger Schrodinger.Erwin solve an equation to obtain the wave function to describe the discovery of a possible limit of the electron in three dimensions.
Model of the atom with the orbital trajectories of electrons is called a model of a modern atom or atomic model of quantum mechanics that applies to this, as shown in the picture below.
Shows the electron cloud around the nucleus where the probability of an electron. Orbital describes the energy levels of electrons. Orbitals with the same energy level or nearly the same to form sub shell. Some sub leather combine to make such kulit.Dengan skin consists of several sub-skin and consists of several orbital subshell. Although the skin is the same position but not necessarily the same orbital position.
Characteristic atomic model of wave mechanics
1. The movement of electrons have wave properties, so the trajectory (orbit) is not stationary as the Bohr model, but following the completion of the square of the wave functions called orbitals (three-dimensional shape darikebolehjadian greatest discovery of the electron in the particular circumstances of an atom)
2. The shape and size of the orbital depends on the price of the three quantum numbers. (The electrons occupy orbital quantum numbers are expressed in)
3. The position of the electron from the nucleus as far as 0.529 Armstrong H according to Bohr rather than anything concrete, but it is probable the discovery of the electron greatest opportunities.


C. QUANTUM NUMBERS
To determine the position of an electron in an atom, used 4
quantum numbers.
1. The principal quantum number (n): realizing the electron trajectories in
atom.
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 of electrons = 2 x 42 = 32
electron
2. Azimuthal quantum number (l): indicate sub skin where
electrons that move also shows a sub-skin
compilers of the 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)
l = 3; fit leather sub f (f = fundamental)
3. Magnetic quantum number (m): realizing the presence of one or
several levels of energy in a sub shell. Quantum numbers
magnetic (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 (f sub shell), price m = -3, -2, O, +1, +2, +3 (have 7
orbital)
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 second
This electron spins through the axis in the opposite direction, and
each one is priced spin +1 / 2 or -1 / 2.
Question:
How the four states of the electron quantum numbers 3S1?
Answer:
The four quantum numbers of the electron position can 3S1
expressed as,
n = 3; l = 0; m = 0; s = +1 / 2, or -1 / 2
D. ELECTRON CONFIGURATION
In every atom orbitals are available, but not necessarily
all orbital is filled. How is the electron charge
these orbitals?
Completion of electrons in the orbitals satisfy some rules.
among other things:
1. Aufbau principle: electrons fill orbitals starting with
the lowest energy level and beyond.
Orbital who meet the low energy levels is 1s
followed by 2s, 2p, 3s, 3p, and on and on
made easier following diagram:
Examples of filling electrons in orbitals several elements:
Atom H: has 1 electron, configuration 1s1
Atom C: has 6 electrons, the configuration 1s2 2s2 2P2
Atom C: has 19 electrons, the configuration 1s2 2s2 2P6 3S2 3P6
4S1
2. Pauli principle: not possible in the atom there are two electrons
with the same four quantum numbers.
This means, if there are two electrons that have a number
principal quantum, and magnetic azimuth of the same, then the number
quantum spins must be opposite.
3. Principle Hund: for filling electrons in orbitals in a sub
Skin is that the electrons do not form pairs of electrons
before each filled with an electron orbital.
Example:
- Atom C with an atomic number of 6, meaning it has 6 electrons and how
Charging orbitals are:
Based on the principle Hund, the first electron from 2s trajectory will
move to track 2pz, so now there are 4 electrons
pairs. Therefore, for all orbital is full, then the atom
carbon bonded to elements that can give 4 electrons.
So that in nature there is a compound CH4 or CCl4, but there is no
CCl3 compound or CCL5.