UTS 14,NOVEMBER 2012
1. pure substance X is solid at room temperature. if the substance is heated to 230 ℃ is melted gradually. if then cooled to room temperature, the liquid can not be frozen.
a) is it possible X of an element or a compound. explain it!
answer : X is a compound. The compound is a collection of several elements. If a compound in the melt by the heat will melt easier. But it will be difficult molten liquid solidifies at the same temperature setting before him in the melt. If you want to make it freeze then the need is even lower temperatures. It may be a temperature below 0 ℃.
b) does it a chemical change occurred ? if so can it be said to undergo an endotherm changing, based on the information provided?
answer : chemical changes that occur can be called endothermic reactions. Endothermic reaction is a reaction that is accompanied by heat transfer from the environment to the system (heat absorbed by the system from its environment); characterized by a decrease in ambient temperature around the system. Substance X which initially are solid when heated at a temperature of 230 ℃ to melt in the heat in the environment caused due to move to the substance, so that the substance to be melted and the temperature in the substance becomes higher than
the temperature of their environment.
c) Can it be said that the liquid is an element, based on the information provided.
answer : there are elements which are in fluid. For instance mercury. But based on the information that is given me to say that it's open compound elements.
2. When
the wax weight of 10 grams burned in oxygen, carbon dioxide and water
vapor formed by the combustion weigh more than 10 grams. Is this game any case law of mass. Explain.
The answer is:
Including
the law of mass eternity (lavoiser) burned candles will melt and when
cooled again will freeze again, in the process also formed wax
pembekaran Co2 + H2O in the form of gas, it was the cause of the change
in mass before and after the burn bkar, but if the count is its chemical calculations should no striking difference in the mass before and after the fuel is burned.
3. When carbon burns oxygen with kimited number, will form two gas compounds. Suggest a way to differentiate the two compounds with one another?
the answer is:
was about the enthalpy of combustion ...
Her compound is Karb on dioxide and water,
How to distinguish is because each process will generate the combustion gases are CO2 + 2 H2O,
while the incomplete combustion CO + H2O.
more details are to distinguish the two compounds with one another by adding a non-polar compounds or compounds that make the state reached saturation point.
4. After mendeev compiled theperiodic table, he concluded that the atomic weights of some elements was the wrong decision, and this conclusion appears to be true. How Mendeleev able to predict that the atomic weight of some wrong? Why predictions are not always right. Explain!
the Answer is:
conclusions do seem true
Medeleev because taking the average total value of the four elements to determine the elements sought.
According to Mendeleev,
"If there is a particular group of elements, R1, R2, R3, and if some elements of R2 are elements of Q2 and T2, then the properties of R2 is determined by the average properties of the R1, R3, Q2 and T2"
why ramalanya is not always true. because the difference between the masses is not always 2, but the range of 1 and 4
OR
Mendeleyev had predicted the properties of elements and it is a prophecy after the elements were found. Arrangement of the elements of Mendeleev perfected under the law and called Mendeleev periodic system.
Mendeleev periodic system consisting of groups (elements located in a single column) and period (the elements which lie on one line)
5.. When mekuri chloride solution is added to a solution of silver nitrate, a white solid forms. Identification of a white solid and write a balanced equation for the reaction.?
the answer is
Sediment on the results of a white precipitate of silver nitrate ..
her reksih
Hg2CL2 AgNO3 ------ + Hg (No3) 2 + HgCl2
equalization reraksi
HgCl2 + 2AgNo3 = HG (No3) 2 + 2AgCl
White solid: AgCl
Rabu, 14 November 2012
Sabtu, 03 November 2012
Atomic Structure and the Periodic System Elements
At this time have been found over a hundred elements and so many chemical compounds that have been biosynthesized. How can we easily learn the elements of it? The chemists have grouped elements based on the properties of chemical and physical properties that are similar or the same.
To learn grouping elements by their nature can be used periodic table of elements. Elements Periodic Table of classification evolved from simple to complete. The periodic table used today is the modern periodic table are arranged by atomic number increases and the similarity of the properties of the elements. In the modern periodic table, elements are grouped into classes and periods.
Element on the periodic table, the symbol of the element is equipped with atomic mass and atomic number. From these data we can determine the atomic structure of an element ffffseperti protons, neutrons, electrons and electron configuration.
In the periodic table of elements we unsuir DAPT study the properties of metals, metalloids, non-metals, and the periodic nature of the fingers, enenrgi ionization, electron affinity, and electronegativity.
A. Development of the Periodic Table of Elements
Grouping elements initiated by the Antonine Lavovoisier grouping elements into metals and non-metals. Furthermore, grouping elements developed in various forms and is known by Triade Doberiener, Octave Newlands, Lothar Meyer Periodic Table of Elements and Mendeleve and Modern Periodic Table.
1. Periodic Table of Elements Antoine Lavoisier
Antoine Lavoisier in 1789, a French chemist dividing the elements into four groups. To know the classification, consider Table 1.1.
Table 1.1 Classification of the element by Antoine Lavoisier
Listed in Table 1.1 and the heat instead of light elements. In group IV included compounds that can not be decomposed into elements known today.
2. Law Triade Dobereiner
J.W. Dobereiner in 1817 grouping the elements that have similar properties, each group consisting of three elements called triade.
To study these laws do activities follows.
Dobereiner tried grouping elements that have the same properties of increasing atomic mass, was obtained regularity. If the three elements sorted by atomic mass increases, the mass of the second element equal to the average mass of the first and third elements. This statement is known as the Law of Triade Dobereiner.
3. Newlands Law of Octaves
In 1863, J.W. Newlands sort the elements based on atomic mass increases. How to order a discovery? Try grouping discussed through the following activities
From this grouping apparently the eighth element has similar properties to the first element, as well as elements of the ninth character is similar to the second element, and so on. For example, elements similar to the elements of nature H F and Cl, elements like Li Na and K, as well as elements like Mg Be.
Repetition is the so-called Law of Octaves Newlands as he compared the recurrence properties of elements with scales or octaves on track. Newlands pioneered the preparation of the elements that are similar in vertical columns. Weakness law of octaves that repetition every 8 elements fit only for elements that small atomic mass. In addition there are coincident elements in the same order.
4. Periodic Table of Elements Lothar Meyer
In 1870, Lothar Meyer tried to make a list of the elements with respect to the physical properties of atomic volume. He made the atomic volume graph element to the atomic mass.
To learn how to do the following activities.
In curved Meyer, elements Li, Na, K, Rb, and Cs occupies an equivalent position, which is at the top. Be, Mg, Ca, Sr, and Ba is the second point of the peak. It turns out that the location elements have properties similar equivalent.
5. Mendeleev Periodic Table of Elements
Dimitri Ivanovich Mendeleev in 1869 in Russia put forward the relationship between the mass of an element with the properties of elements. In studying the periodikan elements, Mendeleev than using physical properties also use chemical properties. In research such as New-lands, Mendeleev also arrange elements by atomic mass increases relative and he found no change in the nature of a periodic basis.
Excess Mendeleev periodic table of elements is as follows.
a. The first is the periodic table arranged in the form of eight vertical columns or groups, and seven rows of horizontal or period. Hereinafter referred Mendeleev periodic table of elements.
b. There's an empty place for elements predicted to be found and named eka boron, eka aluminum, and eka silicon. Divination is proved by the discovery of Scandium (1879), Gallium (1875), and Germa-nium (1886). Examples forecast for Germanium Mendeleev called eka silicon listed in Table 1.2.
Mendeleev Table 1.2 Predictions of the nature of the element germanium
c. put the elements He, Ne, Ar, Kr, Xe, and Rn in a separate class after class of noble gases found.
Mendeleev periodic table of elements is described as follows.
Besides advantages, Mendeleev periodic table of elements has several disadvantages as follows.
a. There are some elements of the reverse order when viewed from the increasing relative atomic mass, such as Te (128) placed before the I (127).
b. Triade iron (Fe, Co, Ni), platinum triade light (Ru, Rh, Pd), and platinum triade (Os, Ir, Pt) included in class VIII. Among the elements of this group can only Ru and Os that have valence 8.
6. Modern Periodic Table
Periodic table of elements digunakn now the Modern Periodic Table of Elements. After the periodic table of elements Mendeleev, in 1915 Henry Mosley discover and develop atomic number elements in the periodic table by atomic number increases and menyususun preformance elements of the periodic table by atomic number increases increases. several studies, showing the relationship between the atomic number of the element properties, so Mendeleev table peridik need improvement. Modern elements on the periodic table are arranged in groups and periods
There are 2 numbering system used on golomgan the American system and the IUPAC system. The American system using Roman numerals I through VIII, maing each consisting of class A and B. System IUPAC (International Union Pure and Applied Chemistry) using Arabic agka 1 to 18.
Therefore IPAC group numbering system has not been socialized among chemists, the American sisatem pengolongan more widely used so well in Indonesia.
Modern periodic table of elements are described as follows.
Predictions about the nature of the element germanium Mendeleev
c. put the elements He, Ne, Ar, Kr, Xe, and Rn in a separate class after class of noble gases found.
Mendeleev periodic table of elements is described as follows.
Besides advantages, Mendeleev periodic table of elements has several
disadvantages as follows.
To learn grouping elements by their nature can be used periodic table of elements. Elements Periodic Table of classification evolved from simple to complete. The periodic table used today is the modern periodic table are arranged by atomic number increases and the similarity of the properties of the elements. In the modern periodic table, elements are grouped into classes and periods.
Element on the periodic table, the symbol of the element is equipped with atomic mass and atomic number. From these data we can determine the atomic structure of an element ffffseperti protons, neutrons, electrons and electron configuration.
In the periodic table of elements we unsuir DAPT study the properties of metals, metalloids, non-metals, and the periodic nature of the fingers, enenrgi ionization, electron affinity, and electronegativity.
A. Development of the Periodic Table of Elements
Grouping elements initiated by the Antonine Lavovoisier grouping elements into metals and non-metals. Furthermore, grouping elements developed in various forms and is known by Triade Doberiener, Octave Newlands, Lothar Meyer Periodic Table of Elements and Mendeleve and Modern Periodic Table.
1. Periodic Table of Elements Antoine Lavoisier
Antoine Lavoisier in 1789, a French chemist dividing the elements into four groups. To know the classification, consider Table 1.1.
Table 1.1 Classification of the element by Antoine Lavoisier
Listed in Table 1.1 and the heat instead of light elements. In group IV included compounds that can not be decomposed into elements known today.
2. Law Triade Dobereiner
J.W. Dobereiner in 1817 grouping the elements that have similar properties, each group consisting of three elements called triade.
To study these laws do activities follows.
Dobereiner tried grouping elements that have the same properties of increasing atomic mass, was obtained regularity. If the three elements sorted by atomic mass increases, the mass of the second element equal to the average mass of the first and third elements. This statement is known as the Law of Triade Dobereiner.
3. Newlands Law of Octaves
In 1863, J.W. Newlands sort the elements based on atomic mass increases. How to order a discovery? Try grouping discussed through the following activities
From this grouping apparently the eighth element has similar properties to the first element, as well as elements of the ninth character is similar to the second element, and so on. For example, elements similar to the elements of nature H F and Cl, elements like Li Na and K, as well as elements like Mg Be.
Repetition is the so-called Law of Octaves Newlands as he compared the recurrence properties of elements with scales or octaves on track. Newlands pioneered the preparation of the elements that are similar in vertical columns. Weakness law of octaves that repetition every 8 elements fit only for elements that small atomic mass. In addition there are coincident elements in the same order.
4. Periodic Table of Elements Lothar Meyer
In 1870, Lothar Meyer tried to make a list of the elements with respect to the physical properties of atomic volume. He made the atomic volume graph element to the atomic mass.
To learn how to do the following activities.
In curved Meyer, elements Li, Na, K, Rb, and Cs occupies an equivalent position, which is at the top. Be, Mg, Ca, Sr, and Ba is the second point of the peak. It turns out that the location elements have properties similar equivalent.
5. Mendeleev Periodic Table of Elements
Dimitri Ivanovich Mendeleev in 1869 in Russia put forward the relationship between the mass of an element with the properties of elements. In studying the periodikan elements, Mendeleev than using physical properties also use chemical properties. In research such as New-lands, Mendeleev also arrange elements by atomic mass increases relative and he found no change in the nature of a periodic basis.
Excess Mendeleev periodic table of elements is as follows.
a. The first is the periodic table arranged in the form of eight vertical columns or groups, and seven rows of horizontal or period. Hereinafter referred Mendeleev periodic table of elements.
b. There's an empty place for elements predicted to be found and named eka boron, eka aluminum, and eka silicon. Divination is proved by the discovery of Scandium (1879), Gallium (1875), and Germa-nium (1886). Examples forecast for Germanium Mendeleev called eka silicon listed in Table 1.2.
Mendeleev Table 1.2 Predictions of the nature of the element germanium
c. put the elements He, Ne, Ar, Kr, Xe, and Rn in a separate class after class of noble gases found.
Mendeleev periodic table of elements is described as follows.
Besides advantages, Mendeleev periodic table of elements has several disadvantages as follows.
a. There are some elements of the reverse order when viewed from the increasing relative atomic mass, such as Te (128) placed before the I (127).
b. Triade iron (Fe, Co, Ni), platinum triade light (Ru, Rh, Pd), and platinum triade (Os, Ir, Pt) included in class VIII. Among the elements of this group can only Ru and Os that have valence 8.
6. Modern Periodic Table
Periodic table of elements digunakn now the Modern Periodic Table of Elements. After the periodic table of elements Mendeleev, in 1915 Henry Mosley discover and develop atomic number elements in the periodic table by atomic number increases and menyususun preformance elements of the periodic table by atomic number increases increases. several studies, showing the relationship between the atomic number of the element properties, so Mendeleev table peridik need improvement. Modern elements on the periodic table are arranged in groups and periods
There are 2 numbering system used on golomgan the American system and the IUPAC system. The American system using Roman numerals I through VIII, maing each consisting of class A and B. System IUPAC (International Union Pure and Applied Chemistry) using Arabic agka 1 to 18.
Therefore IPAC group numbering system has not been socialized among chemists, the American sisatem pengolongan more widely used so well in Indonesia.
Modern periodic table of elements are described as follows.
Predictions about the nature of the element germanium Mendeleev
c. put the elements He, Ne, Ar, Kr, Xe, and Rn in a separate class after class of noble gases found.
Mendeleev periodic table of elements is described as follows.
Besides advantages, Mendeleev periodic table of elements has several
disadvantages as follows. |
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