A metal is a chemical element that is a good conductor of both electricity and heat and forms cation and ionic bonds with non-metal.
Two properties of metals and non-metals:
Metals - They are malleable
-They are lustrous
Non-metals - they are poor conductor of heat and electricity compared to metals.
- they have high electronegativity
Three physical properties of metals:
1)Metals are solid at normal temperature except mercury
2)Metal transform to liquid from solid and to gas from liquid at definite temperatures which are high for most metals except mercury, sodium and potassium.
3)Metal reflects equally nearly all visible electromagnetic waves.
Tuesday, October 26, 2010
Monday, October 25, 2010
Waves
A wave is a disturbance that travels through time and space usually by the transfer of energy.There are different types of waves.
1)Longitudinal waves
2)Transverse waves
When the particles of the waves are displaced parallel to the direction of the propagation of the wave, it is called the longitudinal wave.
When the particles of the waves are displaced perpendicular to the propagation of the wave, it is called transverse wave.
You can also see the link given here for the progressive waves.
Next time we will learn about the properties of waves.
1)Longitudinal waves
2)Transverse waves
When the particles of the waves are displaced parallel to the direction of the propagation of the wave, it is called the longitudinal wave.
When the particles of the waves are displaced perpendicular to the propagation of the wave, it is called transverse wave.
You can also see the link given here for the progressive waves.
Next time we will learn about the properties of waves.
Sunday, October 24, 2010
Molecular formula of compounds
A compound is a chemical substance formed from two or more elements which can be separated into its constituent elements.
Now let's learn what is molecular formula of compounds.
Molecular formula of compounds shows the constituent elements of the compound with their symbols and number of atoms on each element contained in the compound.
We will learn how to represent some compounds in their molecular formula.
Lead carbonate - its molecular formulae is 2PbCO3.Pb(OH)2
Sodium Chloride - its molecular formula is NaCl
Carbon dioxide - CO2
Molecular formulas go one step beyond the empirical formula in that they express not only the correct ratio but the correct number of atoms in the molecule.
Now let's learn what is molecular formula of compounds.
Molecular formula of compounds shows the constituent elements of the compound with their symbols and number of atoms on each element contained in the compound.
We will learn how to represent some compounds in their molecular formula.
Lead carbonate - its molecular formulae is 2PbCO3.Pb(OH)2
Sodium Chloride - its molecular formula is NaCl
Carbon dioxide - CO2
Molecular formulas go one step beyond the empirical formula in that they express not only the correct ratio but the correct number of atoms in the molecule.
Monosaccharide structures
Carbohydrates are made up of carbon, hydrogen and oxygen.They are the most abundant source of energy for all living organism.Some of the other functions of carbohydrates include participation in cell growth, it also acts as chief structural material for cell walls in plants.
In their basic form, carbohydrates are simple sugars.These sugars are classified according to the number of carbons.
No.of carbons Category names Examples.
4 Tetrose erythrose
5 pentose arabinose
6 hexose allose
7 heptose sedoheptulose
The structures of carbohydrates are shown below:
D-erythrose D-rebose D-allose D-sedoheptulose
In their basic form, carbohydrates are simple sugars.These sugars are classified according to the number of carbons.
No.of carbons Category names Examples.
4 Tetrose erythrose
5 pentose arabinose
6 hexose allose
7 heptose sedoheptulose
The structures of carbohydrates are shown below:
D-erythrose D-rebose D-allose D-sedoheptulose
Friday, October 22, 2010
Food chain
Food chain of animals is defined as the transfer of food energy from one organism to another organism in an ecology.A food chain of animals starts with producers, then herbivores and ends with carnivores.
For example, herbs and plants are producers, grass-shoppers and cow are herbivores and tigers and wolves are carnivores.
A food web is a graphical representation of food chain system.An example of food web diagram is shown below:
You will find food chain for different animals according to their ecosystem.Animals can be terrestrial or aquatic.
For example, herbs and plants are producers, grass-shoppers and cow are herbivores and tigers and wolves are carnivores.
A food web is a graphical representation of food chain system.An example of food web diagram is shown below:
Pollution
Pollution has become one of the major issues nowadays.Pollution means undesirable state of natural environment being contaminated with harmful substances as a result of human activities.
Polythene pollution is one of the main problem which is created by widespread use of poly-bags and bottles.Polythene is non-bio-degradable.It is one of the causes of floods due to blockage of water.Because of industries and factories, water is being polluted leading to many health hazards.You will find many facts about water pollution in newspapers and magazines.Not only water, air is also polluted with unwanted chemicals in the form of solid particles or air.Carbon monoxide is one of the example of poisonous gas.
Steps have been taken to reduce the use of polythene by replacing it with recyclable paper bags.Limits have been given to different countries by International union in the release of carbon by industries.
Polythene pollution is one of the main problem which is created by widespread use of poly-bags and bottles.Polythene is non-bio-degradable.It is one of the causes of floods due to blockage of water.Because of industries and factories, water is being polluted leading to many health hazards.You will find many facts about water pollution in newspapers and magazines.Not only water, air is also polluted with unwanted chemicals in the form of solid particles or air.Carbon monoxide is one of the example of poisonous gas.
Steps have been taken to reduce the use of polythene by replacing it with recyclable paper bags.Limits have been given to different countries by International union in the release of carbon by industries.
Periodic table
The periodic table of elements is a table that provides information of elements in a systematic manner.It gives the information about the names and properties of elements.
The periodic table is divided into groups and periods.A group is a vertical column in a periodic table.There are 18 groups.The elements in a group have similar electronic configuration of the outermost shell.Electronic configuration of elements is the arrangement of electrons in the shells of an atom.A period is the horizontal row in the periodic table.Elements in a period have the same number of electron shells.
Elements of the Halogen family which are in group 17 in the periodic table is the most reactive elements whereas group 8A consists of elements which are considered as the least reactive elements.
The periodic table is divided into groups and periods.A group is a vertical column in a periodic table.There are 18 groups.The elements in a group have similar electronic configuration of the outermost shell.Electronic configuration of elements is the arrangement of electrons in the shells of an atom.A period is the horizontal row in the periodic table.Elements in a period have the same number of electron shells.
Elements of the Halogen family which are in group 17 in the periodic table is the most reactive elements whereas group 8A consists of elements which are considered as the least reactive elements.
Wednesday, October 20, 2010
Types of motion
What do you mean by Motion?
In physics, motion is the change in position of an object with respect to time.Motion is described in terms of velocity, acceleration, displacement, and time.
There are three types of motion:
1.Translatory motion
2.Rotational motion
3.Vibratory motion.
Translatory motion results in the change in location along some path such as moving of car down the highway.Rotational motion is the motion around an axis such as the rotation of the Earth.Vibratory motion is moving of an object back and forth such as moving of a pendulum.
In physics, motion is the change in position of an object with respect to time.Motion is described in terms of velocity, acceleration, displacement, and time.
There are three types of motion:
1.Translatory motion
2.Rotational motion
3.Vibratory motion.
Translatory motion results in the change in location along some path such as moving of car down the highway.Rotational motion is the motion around an axis such as the rotation of the Earth.Vibratory motion is moving of an object back and forth such as moving of a pendulum.
Chemical reaction
A chemical reaction is a process that results in the transformation of one set of chemical substance to another.Chemical reactions may be reversible or irreversible.
In a reversible reaction,the products of the reactions can be converted back to the reactants.Whereas in an irreversible reaction, the products of the reactions cannot be converted back to the reactants.
For example, Ammonium chloride which has been converted to ammonia and hydrogen chloride by heating can be reversed back to ammonium chloride when cold.
Example of irreversible reaction is given below:
NaOH + HCl –> NaCl + H2O + 13.7 kcal
In a reversible reaction,the products of the reactions can be converted back to the reactants.Whereas in an irreversible reaction, the products of the reactions cannot be converted back to the reactants.
For example, Ammonium chloride which has been converted to ammonia and hydrogen chloride by heating can be reversed back to ammonium chloride when cold.
Example of irreversible reaction is given below:
NaOH + HCl –> NaCl + H2O + 13.7 kcal
Properties of Hydrochloric acid
Historically, Hydrochloric acid is also called Muriatic acid.It is a solution of HCl in water.It is a highly corrosive, strong mineral acid with many industrial uses and is found naturally in gastric acid.
Some of the properties of Hydrochloric acid are:
a)It turns litmus paper from blue to red.
b) It turns methyl orange from yellow to pink.
c) It turns phenolpthalein (alkaline) from deep pink to colorless.
d)It reacts with metals to form their respective chlorides and liberates hydrogen.Example is given below;
There are many more properties of Hydrogenchloric acid.
Some of the properties of Hydrochloric acid are:
a)It turns litmus paper from blue to red.
b) It turns methyl orange from yellow to pink.
c) It turns phenolpthalein (alkaline) from deep pink to colorless.
d)It reacts with metals to form their respective chlorides and liberates hydrogen.Example is given below;
There are many more properties of Hydrogenchloric acid.
Dipole moment
Molecules are formed by sharing electrons. In a molecule, if there is a pair of electrons, one with negative charge and the other one with positive charge and if the center of the negative charge do not coincide with the center of the positive, then the extent of polarity in this covalent molecule is known as the dipole moment.
Dipole moment = magnitude of the charge x distance of separation
Dipole moment is a vector quantity and is represented by a small arrow with tail at the positive center and head pointing towards a negative center.
For example, the dipole moment of HCl molecule is 1.03 D and that of H2O is 1.84 D. The dipole of HCl may be represented as follows:
Dipole moment = magnitude of the charge x distance of separation
Dipole moment is a vector quantity and is represented by a small arrow with tail at the positive center and head pointing towards a negative center.
For example, the dipole moment of HCl molecule is 1.03 D and that of H2O is 1.84 D. The dipole of HCl may be represented as follows:
Tuesday, October 19, 2010
Ocean decomposers
Decomposers are living organisms that act as cleaner as they decompose the remains of plants and animals.They are mainly bacteria and fungi.
Since ocean occupies 70% of the Earth's surface, it has numerous number of ocean decomposers. According to depth and availability of sunlight and temperature, the ocean is divided into different zones and therefore, different types of decomposers are found in the ocean.
Some of the names of ocean decomposers are brittle stars, seagulls, sea slugs, sea worms and hagfish.
Since ocean occupies 70% of the Earth's surface, it has numerous number of ocean decomposers. According to depth and availability of sunlight and temperature, the ocean is divided into different zones and therefore, different types of decomposers are found in the ocean.
Some of the names of ocean decomposers are brittle stars, seagulls, sea slugs, sea worms and hagfish.
Reactivity series of metals
Reactivity series is an empirical series of metals in order of their reactivity from highest to lowest.
In the reactivity series of metals, going from bottom to top,1. the metals increase in reactivity 2.lose electrons more readily to form positive ions 3.corrode or tarnish more readily 4.require more energy (and different methods) to be separated from their ores 5.become stronger reducing agents.
The most active metal, potassium, is at the top of the list and the least reactive metal, gold, is at the bottom of the list.
The greater the ease with which an element loses its electrons and acquires a positive charge, the greater is its reactivity. Further, the greater the number of shells and lesser the number of valence electrons, the greater is the reactivity of the metal.
In the reactivity series of metals, going from bottom to top,1. the metals increase in reactivity 2.lose electrons more readily to form positive ions 3.corrode or tarnish more readily 4.require more energy (and different methods) to be separated from their ores 5.become stronger reducing agents.
The most active metal, potassium, is at the top of the list and the least reactive metal, gold, is at the bottom of the list.
The greater the ease with which an element loses its electrons and acquires a positive charge, the greater is its reactivity. Further, the greater the number of shells and lesser the number of valence electrons, the greater is the reactivity of the metal.
Natural resources
As the name suggests natural resources are resources that occurs naturally in our environments.Some of the examples of natural resources are coal, trees, natural gas, limestone, etc.
There are two types of natural resources:
1.Renewable resources:They can be reproduced easily. Sunlight, air, wind, etc., are continuously available and their quantity is not affected by human consumption.
2.Non-renewable resources:Minerals and fossil fuels take a long time to formed, so once exhausted by human consumption, its difficult to replenish.They are known as non-renewable resources.
On the basis of availability, natural resources can be categorized as exhaustible and non-exhaustible resources.Air and water are categorized as non-exhaustible since they are abundantly available.Coal and petroleum are examples of exhaustible natural resources.
There are two types of natural resources:
1.Renewable resources:They can be reproduced easily. Sunlight, air, wind, etc., are continuously available and their quantity is not affected by human consumption.
2.Non-renewable resources:Minerals and fossil fuels take a long time to formed, so once exhausted by human consumption, its difficult to replenish.They are known as non-renewable resources.
On the basis of availability, natural resources can be categorized as exhaustible and non-exhaustible resources.Air and water are categorized as non-exhaustible since they are abundantly available.Coal and petroleum are examples of exhaustible natural resources.
Corrosion of iron
What do you understand by corrosion of iron?
Corrosion of iron is also called rusted iron.Rusted iron is formed when iron is converted to iron oxide.It is formed when iron is in contact with water and oxygen.Rusted iron can also be formed because of the reaction of iron and chlorine in an environment deprived of oxygen.
Examples of rusted iron which are also called iron oxides are given as follows:
Hydrated iron(iii) oxide Fe2O3·nH2O and iron (iii) oxide-hydroxide Fe(OH)3).
In order to prevent corrosion of iron, galvanization method is used, i.e, layering the surface of iron with zinc.
Several other methods are also available for prevention of corrosion.
Corrosion of iron is also called rusted iron.Rusted iron is formed when iron is converted to iron oxide.It is formed when iron is in contact with water and oxygen.Rusted iron can also be formed because of the reaction of iron and chlorine in an environment deprived of oxygen.
Examples of rusted iron which are also called iron oxides are given as follows:
Hydrated iron(iii) oxide Fe2O3·nH2O and iron (iii) oxide-hydroxide Fe(OH)3).
In order to prevent corrosion of iron, galvanization method is used, i.e, layering the surface of iron with zinc.
Several other methods are also available for prevention of corrosion.
Momentum
What is momentum?
Object in motion is said to have momentum.Momentum has a size and direction and is a conserved quantity in physics.
The momentum formula is given as ;
P = mv, where p is the momentum of the moving object, m is the mass and v is the velocity.
From the formula we can say that momentum of a moving object is directly proportional to its mass and velocity.Momentum is classified as linear and angular momentum.
There are laws of conservation of momentum.We will learn about them with examples next time.
I hope you will find this article on momentum helpful.Please do post comments.
Object in motion is said to have momentum.Momentum has a size and direction and is a conserved quantity in physics.
The momentum formula is given as ;
P = mv, where p is the momentum of the moving object, m is the mass and v is the velocity.
From the formula we can say that momentum of a moving object is directly proportional to its mass and velocity.Momentum is classified as linear and angular momentum.
There are laws of conservation of momentum.We will learn about them with examples next time.
I hope you will find this article on momentum helpful.Please do post comments.
Properties of compounds
Let us first try to understand what are compounds before we discuss the properties of compounds.
A compound is a substance formed when two or more elements are chemically joined.
Some of the examples of compounds are sodium chloride, ferrous-oxide, etc.
Properties of compounds:
1.Compounds cannot be separated into its constituent elements by physical or mechanical means.
2.Properties of a compound and its constituents are very different.For example, carbon monoxide is compound of carbon and oxygen.Its is highly toxic to human beings and animals in high quantity whereas carbon and oxygen are not toxic.
2.A compound is a homogenous substance.
All compounds can exist as solid at low enough temperature.
A compound is a substance formed when two or more elements are chemically joined.
Some of the examples of compounds are sodium chloride, ferrous-oxide, etc.
Properties of compounds:
1.Compounds cannot be separated into its constituent elements by physical or mechanical means.
2.Properties of a compound and its constituents are very different.For example, carbon monoxide is compound of carbon and oxygen.Its is highly toxic to human beings and animals in high quantity whereas carbon and oxygen are not toxic.
2.A compound is a homogenous substance.
All compounds can exist as solid at low enough temperature.
Branches of chemistry
Chemistry is the science of matter and the changes it undergoes.It is concerned with the composition, behavior, structure, and properties of matter as well as the changes it undergoes during chemical reactions.
There are six branches of chemistry.
1.Organic chemistry
2.Inorganic chemistry
3.Physical chemistry
4.Analytical chemistry
5.Bio-chemistry
6.Nuclear chemistry.
Organic chemistry deals with organic compounds where as inorganic chemistry deals with inorganic compounds.Physical chemistry deals with atoms and sub-atomic particles.Analytical chemistry deals with analysis of the materials, be it natural or man-made.Bio-chemistry deals with the cells, their structures and composition.Nuclear chemistry deals with nuclear material and their radioactivity.
There are six branches of chemistry.
1.Organic chemistry
2.Inorganic chemistry
3.Physical chemistry
4.Analytical chemistry
5.Bio-chemistry
6.Nuclear chemistry.
Organic chemistry deals with organic compounds where as inorganic chemistry deals with inorganic compounds.Physical chemistry deals with atoms and sub-atomic particles.Analytical chemistry deals with analysis of the materials, be it natural or man-made.Bio-chemistry deals with the cells, their structures and composition.Nuclear chemistry deals with nuclear material and their radioactivity.
Monday, October 18, 2010
Properties of oxygen
Oxygen is indispensable for human beings and all living things both plants and animals.We use oxgygen for respiration.It has the chemical symbol as O2.
Properties of oxygen:
Physical properties:Oxygen is colorless, odorless and a tasteless diatomic gas under normal conditions.It is slightly heavier than air.Oxygen is sparingly soluble in water.
Chemical properties:Oxygen is combustible.All metals and non- metals react with oxygen to form their respective oxides.Oxygen oxidizes many compounds under suitable condition.
For example, hydrogen chloride gets oxidized to chlorine.
Because of its varied properties, oxygen is used for many purposes such as in steel making, for preparing oxygen containing organic compounds, such as ethylene oxide, phenol, etc. For medical purposes where O2 is required for emergency operations and respiratory.Oxygen is also used as an oxidizer in rocket propellants and in fuel cells.
Properties of oxygen:
Physical properties:Oxygen is colorless, odorless and a tasteless diatomic gas under normal conditions.It is slightly heavier than air.Oxygen is sparingly soluble in water.
Chemical properties:Oxygen is combustible.All metals and non- metals react with oxygen to form their respective oxides.Oxygen oxidizes many compounds under suitable condition.
For example, hydrogen chloride gets oxidized to chlorine.
Because of its varied properties, oxygen is used for many purposes such as in steel making, for preparing oxygen containing organic compounds, such as ethylene oxide, phenol, etc. For medical purposes where O2 is required for emergency operations and respiratory.Oxygen is also used as an oxidizer in rocket propellants and in fuel cells.
Propanone
Acetone is another name of propanone which is a highly inflammable liquid widely used as an organic solvent and as material for making plastics.
There are different ways of preparing acetone:
1.By dehydrogenation of propane-2-ol using heated copper.
2.By dry distillation of calcium acetate.
3.By Wacker Process.
Acetone is used as solvent in paints, varnishes and lacquers.It can remove the lustre from a textile for cellulose acetate fibres. It is used in the preparation of smokeless gun powder and unbreakable glass and for specification testing of vulcanised rubber products, as nail polish remover and to clean and dry parts of precision equipment.
There are different ways of preparing acetone:
1.By dehydrogenation of propane-2-ol using heated copper.
2.By dry distillation of calcium acetate.
3.By Wacker Process.
Acetone is used as solvent in paints, varnishes and lacquers.It can remove the lustre from a textile for cellulose acetate fibres. It is used in the preparation of smokeless gun powder and unbreakable glass and for specification testing of vulcanised rubber products, as nail polish remover and to clean and dry parts of precision equipment.
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