PENGENALAN DASAR STRUKTURATOMBASIC INTRODUCTION TOATOMIC STRUCTURE
ATOM IS THE BASIC UNIT OF MATTER COMPOSED OF ATOMIC NUCLEUS AND NEGATIVELY CHARGED ELECTRONS SURROUNDING IT.The picture above is the pictureof atomic structure
Developing of Atomic Theory and Model Bohr’sDemocritus’ Rutherford’s The modern John Dalton’s J.J Thomson’s Atomic Atomic Atomic Theory View of Atomic Atomic Theory Atomic Theory Theory andTheory and and Model Theory and and Model and Model Model Model Model
1. DEMOCRITUS’ ATOMIC THEORYAND MODEL Democritus, an ancient Greek’s philosopher who lived from 460 BC to 370 BC, has developed a matter composing theory. According to Democritus, if a stone divided and we did it repeatedly until it is undivided any more, every pieces of that stone had the same character with its origin. He labeled the smallest piece of a stone as atomos (A= no, TOMos= divided), which mean “invisible”. Based on his theory, every atom that constructed different matter is dissimilar.
2. JOHN DALTON’S ATOMIC THEORY AND MODELEven though Democritus named thetechnical terminology of atom, but theconcept of atom as the smallestparticle was published by John Daltonin 1803. John Dalton explained themodel based on his calculation datawhile observing chemical reactions.Dalton suggested as followeda. Atom is the smallest particle ofmatterb. Atom is small sized and roundshaped, indivisible, neither creatednor destroyed.c. All atoms of given elements areidenticald. Atoms of different elements can bejoined to produce substance withfixed scalee. Atoms combine to makecompound; a given compound alwayshas the same relative number andkind of atoms
3. J.J THOMSON’S ATOMIC THEORYAND MODEL Dalton’s suggestion about atom as the smallest particle was broken after the discovery of electron by Thomson. In 1897, J.J Thomson did an experiment using cathode ray tube.
4. RUTHERFORD’S ATOMIC THEORY ANDMODEL In almost the same time with Thomson’s experiment, four physicists, Henry Becquerel, Marie Curie, Pierre Curie, and Ernest Rutherford, had research with radioactivity. There were three kind of radioactive beams, alpha particle (α) was positively charge, beta particle (β) was negatively charge, and gamma particle (γ) was zero particle. The study of radioactivity gave a breakthrough to Rutherford for making his atomic model and theory.
6. THE MODERN VIEW OF ATOMIC THEORY AND MODELThe incapability of Bohr’s theory inexplaining atomic model aside fromHydrogen and the influence ofmagnetic field was accomplished in1924 by Louis de Broglie. According toBroglie, beside as a particle, electroncam be defined as wave, whilst Bohrhad assumed that electron was onlydefined as particle. This suggestionwas improved by Erwin Schrodingerand Werner Heisenberg whichgenerate the modern atomicmodel, known as mechanical quantumtheory. The main principle of this theoryis the electron motion in surroundingthe nucleus performs characteristic ofwave. The mechanical theory is usedto explain atom and molecule behavior.
DEVELOPMENT OF CHEMICAL ELEMENTSPERIODICAL SYSTEM
1. LAVOISIER ELEMENTS CLASSIFICATION METHOD Lavoisier Chemical Elements ClassificationGroup Gas Non-metal Metal Soil Light Sulfur Antimo Gold Iron CalciumGroup Calor Fosfor n Timbel Silve MagnesiumMembe Oxyge Chloride Arsen Zinc r Baritrs n acid Cobalt Mercu Nickel Alumina Nitro Fluoride Lead ry Platin silica gen acid Mangan Bismut um Hydro Borax molibd h Tungs gen acid enum Coppe ten Boric r
3. CHANCOURTOIS ELEMENTS CLASSIFICATION METHOD In 1862, a France geologist, Alexander Beguyer de Chancourtois, classifiedchemical elements based on its atomic weight raising. These chemical elements were developed into spiral shaped arrangement Atomic weight = 7 + 16n; n= element sequence
4. NEWLAND’S ELEMENTS CLASSIFICATION METHODH F 8 Cl 15 Co/Ni Br Pd I 43 Pt/Ir1 22 29 36 50Li 2 Na 9 K 16 Cu Rb Ag Cs Tl 23 30 37 44 51G 3 Mg Ca Zn Sr Cd Ba/V Pb 10 17 24 31 38 45 52Be 4 Al 11 Cr Y Ce/L U Ta Th 18 25 e 32 39 46 53C 5 Si 12 Ti 19 In Zr Sn W Hg 54 26 33 40 47N 6 P 13 Mn As Di/M Sb Nb Bi 55 20 27 o 34 41 48O 7 S 14 Fe Se Ro/R Te Au Os 56 21 28 u 35 42 49
6. MOSELEY’S ELEMENTS CLASSIFICATION METHODIn 1909 and 1911, Ernest Rutherford found one of the base particles inside theatom, that is proton, and the nucleus. According to Rutherford, atom is acompiledof positively charged atomic nucleus surrounded by negatively electrons in circle.If a metal is shot with high energy electron, X-ray will be emitted.Base on Rutherford’s findings, Henry Moseley studied X-ray and its correlationwith the amount of electrical charge using X-ray spectroscopy. Then, he plottedthe X-ray frequence with the increasing of atomic number. The results show lineartrend that revealed the correlation between atomic number and atomic propertiesperiodically. After that, Moseley arranged the elements based on the increasing ofatomic number in the periodic table form.
7. SEABORG’S ELEMENTSCLASSIFICATION METHOD In 1940, Glenn Seaborg discovered trans- uranium, the elements with atomic number of 94- 102. This finding triggered some difficulties concerning the trans-uranium elements position in periodic table. This problem is finally solved by composing new rows ang generally changed the modern periodic table.
1. ELECTRON Cathode ray tube experiment was first performed William Crookes (1875). The results of his experiment was the discovery of a beam emerging from the cathode to the anode is called the cathode. George Johnstone Stoney (1891) which provides a cathode ray called "electrons". The weakness of Stoney could not explain the notion ofatoms in an element have the same properties while different elements will have different properties, although both have electrons. Antoine Henri Becquerel (1896) determine the rays emitted from radioactiveelements in nature similar to the electron. Joseph John Thomson (1897)William Crookes experiment continued influence of the electric field and magnetic fields in cathode ray tube.
2. Proton If 0 is the electron mass a particle has no mass when the particle has a mass of material that can be measured. So did the fact that the atom was neutral. How could it be neutral atoms and have, if there are only electrons in atoms? Eugene Goldstein (1886) conducted experiments of gas cylinders which have a cathode, the holes were and given an electric charge. It turned out that the electrons formed at the anode to the positive rays are formed that led to the opposite direction through the hole at the cathode. After the various gases tested in this tube, hydrogen is the gas that produces light of the positive charge of both the smallest mass or load, so that these particles called protons. Proton mass = 1 sma (atomic mass units) and the proton charge = +1
4. NEUTRON Prediction of W. Rutherford Bothe and H. Becker (1930) conducted experiments on alpha particle bombardment nuclei of beryllium (Be). It turned out that the particle radiation produced a high penetrating power. The experiment was continued by James Chadwick (1932). It turned out that the radiation particles that cause the high penetrating power is neutral or no charge and its mass is almost equal to the proton. These particles called neutrons.
CALCULATE THE AMOUNT OFPROTON, ELECTRON, AND NEUTRON OF ATOM X = Atom or elements symbol A = mass number = total proton and neutron Z = atomic number = amount of proton Proton and electron have opposite charge. If the total amount of proton and electron is the same, the atom will have zero charge. But if the total amount of proton and electron is different, then atom will charge either positive or negative. Charged atom is called ion. Positive ion is named cation and negative ion is named anion.
THE ELECTRON STRUCTURE OF ATOM(ELECTRON CONFIGURATION)Atomic Electron Configuration of Atomic number within 1-20 Atomic Electron’s number Valence Atomic Electron’s number Valence Elements Electrons Elements Electrons K L M N K L M N 1He 1 1 11Na 2 8 1 1 2He 2 2 12Mg 2 8 2 2 3Li 2 1 1 13Al 2 8 3 3 4Be 2 2 2 14Si 2 8 4 4 5B 2 3 3 15P 2 8 5 5 6C 2 4 4 16S 2 8 6 6 7N 2 5 5 17Cl 2 8 7 7 8O 2 6 6 18Ar 2 8 8 8 9F 2 7 7 19K 2 8 8 1 1 10Ne 2 8 8 20Ca 2 8 8 2 2
CORRELATION OF ELECTRON CONFIGURATIONWITH PERIOD AND GROUP The electron configuration of atom can be used to determine an atom position in periodic table. The group number is determined from the number of its valence electron. While the period number is obtained from the total number of shell filled with electron. Group Number = valence electron Period Number = number of shell filled with electrons
THE ATOMIC RELATIVE MASS OF ELEMENTSIn the beginning, hydrogen was used as standard. Then after that,oxygen began to be used as standard, substitusing hydrogen. In 1961,carbon was used a standard. Atomic mass (in grams) has a very smallvalue. Therefore, scientist agreed to label atomic mass unit (amu) asstandard mass for atom. The value of 1 amu is equal to 1/12 of oneatomic mass of C-12.1 amu = 1/12 x 1 atomic mass of C-12 = 1/12 x 1.99268 x 10-23 gram =1.66 x 10-24 gram
CATEGORIZING ELEMENTS INTO ISOTOPE,ISOBAR AND ISOTON
1. ISOTOPE Isotopes are atoms that have the same atomic number but have different mass numbers. Each isotope of an element have the same chemical properties because the same number of valence electrons Example :
2. ISOBAR Isobar is the elements that have different atomic numbers but the same mass number. Example:
3. ISOTON Atoms are different but have the same number of neutrons. Example: