What Is Periodic Table
What Is Periodic Table
What Is Periodic Table
Table of Contents
What is periodic table? ......................................................................3 History of Periodic table .....................................................................4 Mendeleevs Periodic Table ...............................................................5 Modern Periodic Table .......................................................................7 Groups ...............................................................................................9 Periods ..............................................................................................9 General Features of Periodic Table ................................................... 10 Classification of General Properties .................................................. 10 Metalloids. ...................................................................................... 10 METALS ........................................................................................... 10 Alkali Metals .................................................................................... 11 Alkaline Earth Metals ....................................................................... 11 Non metals ...................................................................................... 12 The Halogens ................................................................................... 12 Transition metals ............................................................................. 13 The noble or inert gases ................................................................... 13 Salient features of Periodic table ...................................................... 15 How elements are placed in periodic table? ..................................... 16 Reference ........................................................................................ 19
Groups Group is a vertical column of elements in the periodic table with the same number of valence electrons. The modern periodic table of the elements contains 18 groups, or vertical columns. Elements in a group have similar chemical and physical properties because they have the same number of outer electrons. Elements in a group are like members of a family--each is different, but all are related by common characteristic Periods Period is the horizontal row of elements in the periodic table. Table with the period number including the numbers of valence electron shells. Along a period, a gradual change in chemical properties occurs from one element to another. For example, metallic properties decrease and nonmetallic properties increase as you go from left to right across a period. Changes in the properties occur because the number of protons and electron increases from left to right across a period or row. The increase in number of electrons is important because the outer electrons determine the element's chemical properties.
General Features of Periodic Table Classification of General Properties The general properties of elements allow them to be divided into three classifications: metals, nonmetals and Metalloids The distribution of metals is shown in your periodic table as boxes colored yellow, purple and two shades of blue. Metalloid elements are in the diagonal boxes colored pink and nonmetal elements are above the diagonal line to the right of the metalloids, in boxes colored green, gold, and red. Notice that hydrogen's box is colored green, even though it is at the top of a group of metals. METALS As you can see, the vast majority of the known elements are metals. Many metals are easily recognized by non-chemists. Common examples are copper, lead, silver and gold. In general, metals have a luster, are quite dense, and are good conductors of heat and electricity. They tend to be soft, malleable and ductile (meaning that they are easily shaped and can be drawn into fine wires without breaking). All of these properties are directly related to the fact that solid metals are crystals formed from positive ions surrounded by mobile electrons. This mobility allows electrons to absorb and reflect light in many wavelengths, giving the metals their typical luster The Group I Alkali Metals and the Group II Alkaline Earths have more metallic characteristics than elements farther right whose square are colored blue.
Alkali Metals The alkali (IA) metals show a closer relationship in their properties than do any other family of elements in the periodic table. Alkali metals are so chemically reactive that they are never found in the element form in nature. All these metals react spontaneously with gases in the air, so they must be kept immersed in oil in the storeroom. They are so soft that they can be cut with an ordinary table knife, revealing a very "buttery", silvery metal surface that immediately turns dull as it reacts with water vapor and oxygen in the air. The chemical reactivity of alkali metals increases as the atomic number increases. Alkaline Earth Metals The alkaline earth (IIA) metals also exhibit the typical metal characteristics of high density, metallic luster and electrical and thermal conductivity. Rocks and minerals containing silica, magnesium, and calcium compounds are widely distributed. These chemicals are also abundant as compounds in sea water. Their chlorides are abundant in sea water. Radium, the largest of the alkaline earths, is a radio active element that occurs naturally only in very small quantities. Chlorophyll, the green coloring in plants, is a magnesium-containing compound. Calcium is a major component of animal bones, teeth and nerve cells. Alkaline earth elements form compounds by losing, or in the case of beryllium, sharing two electrons per atom. These atoms hold their electrons more tightly than alkali metals. They are, therefore, smaller than and not so chemically reactive as the neighboring alkali metals.
Non metals
Nonmetal, or non-metal, is a term used in chemistry when classifying the chemical elements. On the basis of their general physical and chemical properties. There is no rigorous definition for the term "nonmetal" - it covers a general spectrum of behavior. Common properties considered characteristic of a nonmetal include: poor conductors of heat and electricity when compared to metals they form acidic oxides (whereas metals generally form basic oxides) in solid form, they are dull and brittle, rather than metals which are lustrous, ductile or malleable usually have lower densities than metals they have significantly lower melting points and boiling points than metals (with the exception of carbon) Non-metals have high electro negativity.
The Halogens
The halogens or halogen elements are a series of nonmetal elements from Group 17 IUPAC Style (formerly: VII, VIIA) of the periodic table, comprising fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The artificially created element 117, provisionally referred to by the systematic name ununseptium, may also be a halogen.The group of halogens is the only periodic table group which contains elements in all three familiar states of matter at standard temperature and pressure.
Transition metals The transition elements are also known as the transition metals. These elements are very hard, with high melting points and boiling points. Moving from left to right across the periodic table, the five d orbitals become more filled. The d electrons are loosely bound, which contributes to the high electrical conductivity and malleability of the transition elements. The transition elements have low ionization energies. They exhibit a wide range of oxidation states or positively charged forms. The positive oxidation states allow transition elements to form many different ionic and partially ionic compounds.
Element Name The purpose of the element name is obvious. However, many Periodic Tables do not include element names. For those situations you must memorize the symbols that accord to each element name. Element Symbol Each element has a specific one or two letter symbol that is used interchangeably with its name. These should be memorized. Most of the time, symbols quite clearly accord to the name of the element they represent, as C accords to carbon. Occasional, however, an element's name and symbol have little relation. For example, the symbol for mercury is Hg. As you move across a period the atomic number increases. Similarly, as you move down a group the atomic number increases. In this way, the atomic number represents exactly where in the periodic table an element stands. More importantly, and the reason why the ordering of the elements according to atomic number yields elements in groups with similar chemical and physical properties, the atomic number is the same as the number of protons in the nucleus of an atom of an element, and also the same as the number of electrons surrounding the nucleus in a neutral state. Carbon, for example, has six protons and six electrons.
Atomic Mass Along with protons, an atom also contains neutrons in its nucleus. The atomic mass (also called atomic weight) of an element is the combined number of protons and neutrons in the nucleus. Atoms of particular elements generally have different "versions," meaning that elements have atoms with different numbers of neutrons in their nucleus. These different versions are called isotopes. The atomic weight displayed is actually the weighted average of the mass numbers of the various isotopes. The atomic weight for Carbon is 12.01 because around 99% of all carbon is the carbon-12 isotope. Simple Periodic Trends Atomic Number The Atomic number increases from the top left to the bottom right. It ascends sequentially across each period. Atomic Weight Weight The atomic weight of the elements generally increases as you move down a group and across a period. Hydrogen, at the top left of the table, is the lightest element. The unnamed element 112 is the heaviest. There are some instances when this rule does not hold true, however. For instance, because it has a high percentage of isotopes with many neutrons, the atomic weight of tellurium (Te) is higher than that for iodine (I), even though iodine has a higher atomic number.