But before that, let us discuss what is a reactivity in metals? The highly reactive metals are located on the left bottom corner of the Periodic table. They are the Alkali metals of group 1. Thus the bottom most element of group 1 i. Note: Francium is a laboratory made element. It is available in a very less quantity. And hence for any practical purposes, caesium is considered as the most reactive metal in Periodic table.
Caesium has high reactivity, but it is predicted that Francium would have even higher reactivity than that of caesium. Also see: Reactivity of alkali metals with water Explained with animation. Now just think, what should be the conditions or properties that an element should possess to make the electron lost easily.
Now, you know that the elements on the left side of Periodic table have less valence electrons in their outermost orbit. As they possess bigger atomic size, it is easy to remove the valence electrons from the outermost orbit. So they have low ionization energy. I have discussed this in detailed article of Periodic table that electronegativity depends upon the size of an atom. If atomic size is less, then it has more tendency to attract the electron pair means smaller the size, more is the electronegativity.
And if the atomic size is more, then it has less tendency to attract the electron pair means bigger the size, lesser is the electronegativity. Now the elements on the left side of Periodic table have more atomic size.
So they will have less electronegativity. Metals produce ringing sound when they are stuck hard. This indicates that metals are sonorous in nature. All the metals are solids at room temperature except mercury. Metals can be reshaped into thin sheets on applying sufficient pressure on it. This property of metals is known as malleability. The elements are stacked in such a way that elements with similar chemical properties form vertical columns, called groups, numbered from 1 to 18 older periodic tables use a system based on roman numerals.
Groups 1, 2, and 13—18 are the main group elements, listed as A in older tables. Groups 3—12 are in the middle of the periodic table and are the transition elements, listed as B in older tables. The two rows of 14 elements at the bottom of the periodic table are the lanthanides and the actinides, whose positions in the periodic table are indicated in group 3.
Gold-colored lements that lie along the diagonal line exhibit properties intermediate between metals and nonmetals; they are called semimetals. The distinction between metals and nonmetals is one of the most fundamental in chemistry. Metals—such as copper or gold—are good conductors of electricity and heat; they can be pulled into wires because they are ductile; they can be hammered or pressed into thin sheets or foils because they are malleable; and most have a shiny appearance, so they are lustrous.
The vast majority of the known elements are metals. Of the metals, only mercury is a liquid at room temperature and pressure; all the rest are solids. Nonmetals, in contrast, are generally poor conductors of heat and electricity and are not lustrous. Nonmetals can be gases such as chlorine , liquids such as bromine , or solids such as iodine at room temperature and pressure. Most solid nonmetals are brittle, so they break into small pieces when hit with a hammer or pulled into a wire.
As expected, semimetals exhibit properties intermediate between metals and nonmetals. Based on its position in the periodic table, do you expect selenium to be a metal, a nonmetal, or a semimetal?
The atomic number of selenium is 34, which places it in period 4 and group Note, however, that because selenium is close to the metal-nonmetal dividing line, it would not be surprising if selenium were similar to a semimetal in some of its properties. Based on its location in the periodic table, do you expect indium to be a nonmetal, a metal, or a semimetal?
As previously noted, the periodic table is arranged so that elements with similar chemical behaviors are in the same group. Chemists often make general statements about the properties of the elements in a group using descriptive names with historical origins. For example, the elements of Group 1 are known as the alkali metals, Group 2 are the alkaline earth metals, Group 17 are the halogens, and Group 18 are the noble gases.
The alkali metals are lithium, sodium, potassium, rubidium, cesium, and francium. Hydrogen is unique in that it is generally placed in Group 1, but it is not a metal. The compounds of the alkali metals are common in nature and daily life.
Nonmetals are further to the right on the periodic table, and have high ionization energies and high electron affinities , so they gain electrons relatively easily, and lose them with difficulty. They also have a larger number of valence electrons, and are already close to having a complete octet of eight electrons. The nonmetals gain electrons until they have the same number of electrons as the nearest noble gas Group 8A , forming negatively charged anions which have charges that are the group number minus eight.
That is, the Group 7A nonmetals form 1- charges, the Group 6A nonmetals form 2- charges, and the Group 5A metals form 3- charges. The Group 8A elements already have eight electrons in their valence shells, and have little tendency to either gain or lose electrons, and do not readily form ionic or molecular compounds. Ionic compounds are held together in a regular array called a crystal lattice by the attractive forces between the oppositely charged cations and anions.
These attractive forces are very strong, and most ionic compounds therefore have very high melting points. Ionic compounds are typically hard, rigid, and brittle. Ionic compounds do not conduct electricity, because the ions are not free to move in the solid phase, but ionic compounds can conduct electricity when they are dissolved in water.
When nonmetals combine with other nonmetals, they tend to share electrons in covalent bonds instead of forming ions, resulting in the formation of neutral molecules. Keep in mind that since hydrogen is also a nonmetal, the combination of hydrogen with another nonmetal will also produce a covalent bond. Molecular compounds can be gases, liquids, or low melting point solids, and comprise a wide variety of substances.
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