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Element and its Characteristics
ELEMENTS: Substances which cannot be broken further into any other substances by any physical or chemical means are called Elements.
Examples:Hydrogen,Oxygen,Nitrogen...etc...CHARACTERISTICS OF AN ELEMENT:
1.An element is pure and homogenous in nature.
2.An element is made up of same kind of atoms. Different elements have different kind of atoms.
3.Element may react with other elements to form compounds. -
Element and its Characteristics
ELEMENTS: Substances which cannot be broken further into any other substances by any physical or chemical means are called Elements.
Examples:Hydrogen,Oxygen,Nitrogen...etc...CHARACTERISTICS OF AN ELEMENT:
1.An element is pure and homogenous in nature.
2.An element is made up of same kind of atoms. Different elements have different kind of atoms.
3.Element may react with other elements to form compounds. -
Element and its Characteristics
ELEMENTS: Substances which cannot be broken further into any other substances by any physical or chemical means are called Elements.
Examples:Hydrogen,Oxygen,Nitrogen...etc...CHARACTERISTICS OF AN ELEMENT:
1.An element is pure and homogenous in nature.
2.An element is made up of same kind of atoms. Different elements have different kind of atoms.
3.Element may react with other elements to form compounds.
CLASSIFICATION OF ELEMENTS:
Elements are classified into 4 types. They are
i) Metals ii) Non metals iii) Metalloids iv) Noble gases. -
Metals-Physical Properties
METALS:
Luster:
Explanation: Metals exhibit a characteristic shiny or reflective appearance when polished. This property, known as luster, is a result of the ability of metals to reflect light.Conductivity:
Explanation: Metals are excellent conductors of both heat and electricity. This property arises from the presence of a "sea of electrons" in the metallic structure. These delocalized electrons can move freely, facilitating the transfer of heat and electrical energy.Malleability:
Explanation: Metals can be easily hammered or rolled into thin sheets without breaking. This property is attributed to the metallic bonding, where layers of atoms can slide past each other without disrupting the overall structure.Ductility:
Explanation: Metals can be drawn into thin wires without losing their strength. This property is also a consequence of the metallic bonding, allowing atoms to be rearranged into a stretched form without breaking the overall structure.Density:
Explanation: Metals generally have high densities. This is because metals typically have a large number of atoms packed closely together in a crystalline structure. The arrangement of atoms in metals contributes to their relatively high mass per unit volume.
Melting and Boiling Points:
Explanation: Metals generally have high melting and boiling points compared to non-metals. The metallic bond, which involves strong forces of attraction between positively charged metal ions and delocalized electrons, contributes to the stability of the metal structure at high temperatures.Hardness:
Explanation: Metals vary in hardness, with some being relatively soft (e.g., sodium) and others being extremely hard (e.g., tungsten). The hardness of metals is influenced by factors such as crystal structure, impurities, and alloying elements.Opacity:
Explanation: Metals are typically opaque, meaning they do not allow light to pass through. This property contrasts with some non-metals, which may be transparent or translucent.Sonorus:
Explanation: Most of the metals are sonorus in nature, the property by which they produce sounds when beaten.NOTE: *Zinc is neither malleable nor ductile.
*Mercury and Gallium are liquid metals.
* Sodium and Potassium are soft metals. Sodium, Potassium and Mercury have low melting and boiling points. Whereas Gallium has low melting point but high boiling point.
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Metals-Chemical Properties
Chemical Properties:
Reactivity: Metals vary in their reactivity. Some metals, like gold and platinum, are relatively unreactive, while others, like sodium and potassium, are highly reactive.
Corrosion: Many metals can corrode or oxidize when exposed to moisture and oxygen, forming metal oxides. However, some metals, like aluminum and stainless steel, form a protective oxide layer that prevents further corrosion.
Formation of Positive Ions: Metals tend to lose electrons easily, forming positively charged ions (cations).
Alloys:
Definition: Alloys are mixtures of two or more elements, with at least one being a metal.
Purpose: Alloys are often created to enhance the properties of metals, such as improving strength, corrosion resistance, or reducing cost.
Examples: Steel (iron and carbon), bronze (copper and tin), and brass (copper and zinc) are common alloys.Uses of Metals:
Construction: Metals like steel are widely used in construction due to their strength and durability.
Transportation: Aluminum and steel are commonly used in the automotive and aerospace industries for their lightweight and strong properties.
Electronics: Metals like copper and gold are essential components in electrical and electronic devices.
Jewellery: Precious metals like gold and silver are frequently used in jewelry making. -
Non Metals-Physical Properties
NON-METALS:
Non-metals are a class of elements on the periodic table that exhibit distinct physical and chemical properties from metals. Here's an explanation of some key characteristics and properties of non-metals:Physical Properties:
Luster: Non-metals generally lack the characteristic metallic luster. They often appear dull or have a more varied range of appearances.
Conductivity: Non-metals are generally poor conductors of heat and electricity. Unlike metals, they lack the delocalized electrons that can move freely, hindering the flow of electrical current and thermal energy.
Malleability and Ductility: Non-metals are typically brittle and cannot be easily hammered or drawn into thin wires without breaking. They lack the malleability and ductility characteristic of metals.
Density: Non-metals generally have lower densities compared to metals. They often have lighter atomic masses and exist in various states of matter at room temperature, such as gases (like oxygen and nitrogen), liquids (like bromine), or solids (like sulfur and phosphorus).
State of Matter:
Explanation: Non-metals can exist in various states of matter at room temperature. For example, hydrogen and oxygen are gases, bromine is a liquid, and elements like carbon and sulfur can be solids.Melting and Boiling Points:
Explanation: Non-metals typically have lower melting and boiling points compared to metals. Their molecular structures and intermolecular forces are different, resulting in a wide range of melting and boiling points.Opacity:
Explanation: Non-metals can be transparent, translucent, or opaque. While some non-metals like oxygen and nitrogen are colorless and transparent gases, others like sulfur and iodine may exhibit various colors and opacities in different physical states.NOTE: * Graphite(carbon) is good conductor of heat and electricity.
* Iodine and Graphite are lustrous in nature.
* Carbon,Silicon and Boron have high melting and boiling points.
* Bromine is liquid non-metal.
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Non Metals-Chemical Properties
Chemical Properties:
Reactivity: Non-metals vary in their reactivity. Some non-metals, like fluorine and chlorine, are highly reactive and readily form compounds with metals. Others, like noble gases (helium, neon, argon, etc.), are relatively inert and less reactive.
Acidic Nature: Non-metals often exhibit acidic properties when they react with metals. For example, hydrogen, a non-metal, can react with metals to form acidic compounds like hydrogen chloride.
Uses:
Explanation: Non-metals find applications in various industries. For instance, gases like nitrogen are used in food packaging, carbon is crucial in organic chemistry, and non-metallic elements like fluorine and iodine have applications in pharmaceuticals and medical treatments. -
Metalloids
METALLOIDS:
Metalloids, also known as semimetals, are elements that exhibit properties of both metals and non-metals. They are found along the staircase-shaped boundary on the periodic table between metals and non-metals. There are 7 metalloids in nature. The main metalloids include boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), and polonium (Po). Here's an explanation of the key characteristics of metalloids:Intermediate Properties:
Explanation: Metalloids display a combination of properties that are characteristic of both metals and non-metals. These properties can include electrical conductivity, which is intermediate between that of metals and non-metals, as well as varying degrees of luster, malleability, and ductility.Semi-Conductivity:
Explanation: One of the defining features of metalloids is their semi-conductive behavior. They can conduct electricity better than non-metals but not as efficiently as metals. This property makes them important in the field of electronics.Metallic and Non-metallic Oxides:
Explanation: Metalloids can form both metallic and non-metallic oxides. For example, silicon dioxide (SiO2) is a covalent, non-metallic oxide, while germanium dioxide (GeO2) has a more ionic character and exhibits some metallic characteristics.Varied Physical States:
Explanation: Metalloids can exist in various physical states at room temperature. For instance, boron is a solid, silicon is a crystalline solid, arsenic is a brittle solid, and tellurium is a semi-metal with both metal-like and non-metal-like properties.
Chemical Behavior:
Explanation: Metalloids can exhibit varying degrees of chemical reactivity. For example, boron is relatively unreactive, while arsenic can form compounds with both metallic and non-metallic characteristics.
Applications:
Explanation: Metalloids have several practical applications. Silicon, for instance, is a key component in semiconductors used in electronics. Boron is used in the manufacturing of certain glasses and ceramics, and tellurium is used in solar panels. -
Noble Gases and Atomicity
NOBLE GASES:
These elements are found in air in the form of gas in very small amounts.Hence they are called as Rare gases. They are monoatomic in nature.These elements do not react chemically with other elements, so these are also called as Noble gases.
Ex: Helium,Neon,Argon ,Krypton, Xenon and Radon.
NOTE:
* Helium is second lightest element after hydrogen.
* Radon is radioactive element
ATOMICITY:
The number of atoms that constitute a moleculeof an element is called Atomicity.
i) Monoatomic elements:The elements in which each molecule contains only one atom.
Ex:Copper(Cu), Silver (Ag)....
ii)Diatomic elements:The elements in which each molecule contains two atoms.
Ex: Hydrogen (H2),Oxygen (O2).....
iii)Polyatomic elements:The elements in which each molecule contains more than two atoms.
Ex: Ozone(O3), Phosphorus(P4),Sulphur (S8), Boron (B12).
