1:- What is material?
Ans:- A substance or a group of substances that constitute an object is called material
Ex:-iron rod is made up of single substance called iron.
utensils are made up of stainless steel that is made up of group of substancesthat is iron,
nickel, chromium and manganese.
2:- What is matter?
Ans:- Any thing that has mass and occupies space is called matter.
Matter has both mass and volume.
Ex:- air, food, stone, cloud, stars, animals, plants, water, sand etc.
3:- What is mass?
Ans:- Mass is the matter contained in a body.
The SI. unit of mass is Kilogram (kg).
4:- What is volume?
Ans:- The amount of space that a substance occupies is called its volume.
The SI. unit of volume is cubic meter (m3).
The common unit of measuring volume is litre (L).
9:-Write some important points about element.
Elements that have names ending with -ine belong to a group of elements called halogens. Halogens are extremely reactive and readily form compounds.
Element names ending with -on are noble gases, which are inert or nonreactive gases at room temperature.
Most element names end with -ium sometimes -um. These elements are metals, which are usually hard, shiny, and conductive.
10:- What is a molecule?
11:- How many types of molecule? Name them.
12:- What are molecules of an element?
13:-What are molecules of compound?
Ans:- Molecules that are made up of dissimilar atoms are called molecules of a compound
Ex:-
Molecule of water – H2O ( It is made up of two atoms of Hydrogen and one atom of Oxygen )
Molecule of Carbon dioxide – CO2 ( It is made up of one atom of Carbon and two atoms of Oxygen )
14:-What is Compound? Give some example.
Ans:- Compound is a pure substance made up of two or more elements combined in a fixed ratio.
15:- What is mixture? Give some example
Ans:-Mixture is made up of two or more than two substances put together in a random ratio. each substance remaining seperate without combining chemically.
Ex:- mixture of sand and salt , mixture of grains and pebbles , mixture of salt and water
16:- In how many groups elements are divided?
Ex:-
1- Metals are malleable:- All the metals can be hammered and beaten into thin sheets.
Mallebility helps the metals to change their shape and helps in making
different tools.
2- Metals are ductile:- Metals can be stretched into thin wires by the help of a characteristic
called ductillity.
3- Metals are good conductors of heat and electricity:-
All the metals are good conductors of heat.
Silver metal is best conductor of heat but lead is the poorest conductor of heat.
Silver is also good conductor of electricity. The second good conductor is copper.
Bismuth and tungsten are bad conductor of electricity.
4- Metals are Luster:- Metals have unique shine called metallic luster.
Gold and silver are highly lustrous and are used in making jewellery.
5- Metals are solid at room temperature. Only mercury is a metal that is in the form of
liquid at room temperature
6- The melting and boiling points of metals are generally high.
Sodium , potassium , mercury and gallium have low melting and boiling point
7- Metals are sonorous :- metals produce metallic sound when they are hitted with an object.
8:- Metals are generally hard and strong.
Iron is too hard
Aluminium and magnesium are a little soft.
lead is softer
Sodium and Potassium are too soft metals and can be cut with a knife.
9:- Most metals are heavier and have higher density than water. they sink in water.
Sodium and potassium are lighter than water and they may float on water
10:- Metals have high tensile strength. They do not snap under stress.
3- When metals react with dilute acid they form salt and release hydrogen gas .
Metal + Dilute Acids → Salt + Hydrogen gas
3(A):- When Zinc react with Dilute hydrochloric Acid than they form Zinc chloride which is a salt
and release Hydrogen gas
Zinc + Dilute hydrochloric acid → Zinc chloride (salt) + hydrogen gas
Zn + 2HCl → ZnCl2 + H2
3(B):- When Aluminum react with nitric acid then they produce Aluminum nitrate, Nitrogen oxide
and water.
Aluminum + Nitric acid → Aluminum nitrate + Nitrogen oxide + water
4:- When Metal Oxide react with water then they formed Metal Hydroxide that is a base.
Metal Oxide + Water → Metal Hydroxide (Base)
4(A):- When sodium oxide reacts with water then they formed Sodium hydroxide
Sodium oxide + Water →Sodium Hydroxide
4(B):- When Magnesium oxide reacts with water then they formed Magnesium hydroxide
Magnesium oxide + Water →Magnesium Hydroxide
4(C):- When Potassium oxide reacts with water then they formed Potassium hydroxide
Potassium oxide + Water →Potassium Hydroxide
5(A):-When Zinc react with Sodium hydroxide then they formed Sodium zincate and release
Hydrogen gas.
Zinc + Sodium hydroxide → Sodium zincate + Hydrogen gas
5(B):-When Aluminium react with Sodium hydroxide then they formed Sodium aluminate
and release Hydrogen gas.
Aluminium + Sodium hydroxide + Water → Sodium aluminate + Hydrogen gas
2Al + 2NaOH + 2 H2O → 2 NaAlO2 + 2 H2
Certain metals have the capacity to displace some metals from the aqueous solutions of their salts.
A metal placed higher in the activity series can displace the metal that occupies a lower position from the aqueous solution of its salt.
The displacement reaction is not limited to metals only. Even non-metals can take part in these reactions.
Example : Reaction of iron nails with copper sulphate solution.
Take Copper sulphate sollution in a test tube.
Copper Sulphate is an aquas salt sollution which is blue in colour.
Now dipped an Iron nail in Copper sulphate sollution.
Iron displaced the copper from Copper sulphate and form iron sulphate because highly reactive metals replace the low reactive metals.
Ans:- A substance or a group of substances that constitute an object is called material
Ex:-iron rod is made up of single substance called iron.
utensils are made up of stainless steel that is made up of group of substancesthat is iron,
nickel, chromium and manganese.
2:- What is matter?
Ans:- Any thing that has mass and occupies space is called matter.
Matter has both mass and volume.
Ex:- air, food, stone, cloud, stars, animals, plants, water, sand etc.
3:- What is mass?
Ans:- Mass is the matter contained in a body.
The SI. unit of mass is Kilogram (kg).
4:- What is volume?
Ans:- The amount of space that a substance occupies is called its volume.
The SI. unit of volume is cubic meter (m3).
The common unit of measuring volume is litre (L).
1litre = 1dm3
1litre = 1000 mL
1mL = 1cm3
5:- Is matter continuous or particulate?
Ans:- Matter is particulate. It is made up of particles.
6:- Prove that matter is made up of particles.
Ans:- When we dissolve sugar in water the water level doesnot rise but the sugar completely
dissolve into water because the particles of sugar get into the space between particles
of water, so we can say that matter is made up of particles.
7:- What are atoms?
Ans:-Atoms are the smallest unit of matter that have properties of individual element.
He also said that an atom has three fundamental particles as follows-
Electrons
Protons
Neutrons
8:- What is an element? give examples.
Ans:- A substance that is made up of only one kind of atoms is called an element.
An element can not be broken down into simpler substances by any physical or chemical
means.
Helium He 2 2
Dalton’s theory
John Dalton gave Dalton’s theory in which he clearly stated that matter is made of small particles called atoms.7:- What are atoms?
Ans:-Atoms are the smallest unit of matter that have properties of individual element.
Neil Bohr Theory
Neil Bohr stated that An atom is spherical in nature and has a nucleus placed at the center of the atom. Atoms are electrically neutral.He also said that an atom has three fundamental particles as follows-
Electrons
Protons
Neutrons
Electrons
1:- An electron is a stable subatomic particle with a negative electrical charge.
2:- Each electron carries one unit of negative charge that is equal to 1.602 x 10-19 coulomb
3:- It has a very small mass as compared with that of a neutron or proton. The mass of an electron is 9.11 x 10-31 kg. This is about 1/1836 the mass of a proton.
4:- A common symbol for an electron is e–.
5:- electrons orbit around the positively-charged atomic nucleus.
6:- In solids, electrons are responsible for conducting current. This
is because protons are bound within the nucleus, so they are not as
mobile as electrons.
7:- electron was discovered by British physicist J.J.Thomson in 1897.
Protons
1:- A proton is a stable subatomic particle with a positive electrical charge.
2:- Each proton carries one unit of positive charge that is +1e
3:- It has mas that is slightly less than Neutron.
4:- A common symbol for a proton is p or p+
Protons
1:- A proton is a stable subatomic particle with a positive electrical charge.
2:- Each proton carries one unit of positive charge that is +1e
3:- It has mas that is slightly less than Neutron.
4:- A common symbol for a proton is p or p+
5:- Proton is present in the nucleus of an atom.
6:- Number of protons of an element is always equal to the atomic number
7:- both protons and neutrons are found in the atomic nucleus, they are collectively known as nucleons.
8:- The proton was discovered by Ernest Rutherford in the early 1900's .
9:- A proton has a mass of 1.67 x 10-27 kg.
Neutrons
1:- The neutron is a subatomic particle with a mass of 1 and charge of 0.
2:- Neutrons are found with protons in the atomic nucleus.
3:- the number of protons in a atom determines its element, the number of neutrons determines its isotope.
4:- It was discovered by James Chadwick in 1932, earning him the Nobel Prize in Physics in 1935.
5:- A neutron has a mass of 1.67 x 10-27 kg.
9:- A proton has a mass of 1.67 x 10-27 kg.
Neutrons
1:- The neutron is a subatomic particle with a mass of 1 and charge of 0.
2:- Neutrons are found with protons in the atomic nucleus.
3:- the number of protons in a atom determines its element, the number of neutrons determines its isotope.
4:- It was discovered by James Chadwick in 1932, earning him the Nobel Prize in Physics in 1935.
5:- A neutron has a mass of 1.67 x 10-27 kg.
8:- What are orbits of an atom?
Ans:- The electrons of an atom revolves around the nucleus on fixed paths in a fixed pattern
are called orbits of an atom.
9:- What is electronic Configuration?
Ans:- The electron configuration of an atom is the representation of the
arrangement of electrons distributed among the orbital shells.
The maximum number of electrons that can be accommodated in a shell is
based on the principal quantum number (n). It is represented by the
formula 2n2, where ‘n’ is the shell number.
10:- What is valency?
Ans:- Valency refers to the number of electrons in the outermost orbit of an atom.
What is valence shell?
Ans:- The outermost shell of an atom is called the valence shell of the atom.
Ans:- A substance that is made up of only one kind of atoms is called an element.
An element can not be broken down into simpler substances by any physical or chemical
means.
Ex:- Name of the element Symbol of the element atomic number no of protons
Hydrogen H 1 1Helium He 2 2
Lithium Li 3 3
Beryllium Be 4 4
Boron B 5 5
Carbon C 6 6
Nitrogen N 7 7
Oxygen O 8 8
Fluorine F 9 9
Neon Ne 10 10
Sodium Na 11 11
Magnesium Mg 12 12
Aluminum Al 13 13
Silicon Si 14 14
Phosphorus P 15 15
Sulfur S 16 16
Chlorine Cl 17 17
Chlorine Cl 17 17
Argon Ar 18 18
Potassium K 19 19
Calcium Ca 20 20
9:-Write some important points about element.
Ans:- Element remains unaffected by the physical change
There are 118 known in which 92 are natural elements.
Every element has a unique number called atomic number
Atomic number represents number of protons present in particular element.
Protons are present in nucleus of atom of an element.
Elements with names ending with -gen are nonmetals that are gases in pure form at room temperature.
Ex:- Hydrogen , Oxygen , Nytrogen
Elements that have names ending with -ine belong to a group of elements called halogens. Halogens are extremely reactive and readily form compounds.
Ex:- Fluorine , Chlorine , Bromine , Iodine
Element names ending with -on are noble gases, which are inert or nonreactive gases at room temperature.
Ex:- Neon , Argon , Krypton , Xenon , Radon
Most element names end with -ium sometimes -um. These elements are metals, which are usually hard, shiny, and conductive.
Ex:- Sodium (natrium) , potassium ( Kalium ) , Cadmium , Lithium , Radium
All metallic elements discovered 1811 have been given names ending in -ium (occasionally -um)
10:- What is a molecule?
Ans:-Molecule is a group of atoms bonded together, representing the
smallest fundamental unit of a chemical compound that can take part in a
chemical reaction
Ex:-
Molecule of Hydrogen – H2 (It is made up of two
atoms of Hydrogen )
Molecule of oxygen – O2 (It is made up of two atoms
of Oxygen )
Molecule of water – H2O ( It is made up of two
atoms of Hydrogen and one atom of Oxygen )
11:- How many types of molecule? Name them.
Ans:- There are two types of molecule.
1- Molecule of an element
2 - Molecule of a compound
12:- What are molecules of an element?
Ans:- Molecules that are made up of similar atoms are called molecules of element.
Ex:-
Molecule of Hydrogen – H2 (It is made up of two
atoms of Hydrogen )
Molecule of oxygen – O2 (It is made up of two atoms
of Oxygen )
Molecule of Phosphorus – P5 (It is made up of five
atoms of Phosphorus )
13:-What are molecules of compound?
Ans:- Molecules that are made up of dissimilar atoms are called molecules of a compound
Ex:-
Molecule of water – H2O ( It is made up of two atoms of Hydrogen and one atom of Oxygen )
Molecule of Carbon dioxide – CO2 ( It is made up of one atom of Carbon and two atoms of Oxygen )
14:-What is Compound? Give some example.
Ans:- Compound is a pure substance made up of two or more elements combined in a fixed ratio.
Ex:- water – H2O , Carbon dioxide – CO2 , Sodium oxide – Na2O
15:- What is mixture? Give some example
Ans:-Mixture is made up of two or more than two substances put together in a random ratio. each substance remaining seperate without combining chemically.
Ex:- mixture of sand and salt , mixture of grains and pebbles , mixture of salt and water
16:- In how many groups elements are divided?
Ans:- Elements are divided into three groups
1- Metals
2- Non-metals
3-mettaloids
17:- What are metals?
Ans:- Those elements that loose electrons from their outer orbit are called metals .
17:- What are metals?
Ans:- Those elements that loose electrons from their outer orbit are called metals .
Metals are opaque, lustrous elements that are good conductors of heat and electricity. They are minerals that form naturally below the surface of the Earth. They are found either solid or liquid in nature .
Ex:- Physical properties of metal
The physical properties of metals are1- Metals are malleable:- All the metals can be hammered and beaten into thin sheets.
Mallebility helps the metals to change their shape and helps in making
different tools.
2- Metals are ductile:- Metals can be stretched into thin wires by the help of a characteristic
called ductillity.
3- Metals are good conductors of heat and electricity:-
All the metals are good conductors of heat.
Silver metal is best conductor of heat but lead is the poorest conductor of heat.
Silver is also good conductor of electricity. The second good conductor is copper.
Bismuth and tungsten are bad conductor of electricity.
4- Metals are Luster:- Metals have unique shine called metallic luster.
Gold and silver are highly lustrous and are used in making jewellery.
5- Metals are solid at room temperature. Only mercury is a metal that is in the form of
liquid at room temperature
6- The melting and boiling points of metals are generally high.
Sodium , potassium , mercury and gallium have low melting and boiling point
7- Metals are sonorous :- metals produce metallic sound when they are hitted with an object.
8:- Metals are generally hard and strong.
Iron is too hard
Aluminium and magnesium are a little soft.
lead is softer
Sodium and Potassium are too soft metals and can be cut with a knife.
9:- Most metals are heavier and have higher density than water. they sink in water.
Sodium and potassium are lighter than water and they may float on water
10:- Metals have high tensile strength. They do not snap under stress.
Chemical properties of metals
1- Most metals react with oxygen at high temperature to form metal oxide. All metal oxides are
basic in nature.
Metal + Oxygen → Metal oxide (basic oxide)
Ex:- Iron + oxygen → Iron oxide
4Fe + 3O2 → 2Fe2O3
1 (A) :- When sodium is placed in air, it catches fire soon. sodium combined with oxygen to form
sodium oxide.
Sodium + Oxygen → sodium oxide
4Na + O2 → 2 Na2O
1 (B) :- When Potassium is placed in air, it catches fire soon. Potassium combined with oxygen to
Potassium oxide
Potassium + Oxygen → Potassium oxide
4K + O2 → 2K2O
1 (C) :- When Magnesium ribbon exposed to flame, it gets heated and start burning vigorously in air
and giving out a dazzling white flame and forming white ash.
When Magnesium burns in air form Magnesium oxide.
Magnesium + Oxygen → Magnesium oxide
2Mg + O2 → 2MgO
1 (D):- When Copper reacts with moist air , They form greenish coating called copper hydroxide
and copper carbonate
Moist air = oxygen + Carbon dioxide + water
and copper carbonate
Moist air = oxygen + Carbon dioxide + water
Copper + Oxygen + Carbon dioxide + Water → Copper hydroxide + copper carbonate
2Cu + O2 + CO2 + H2O → Cu(OH)2 + CuCO3
2Cu + O2 + CO2 + H2O → Cu(OH)2 + CuCO3
2- When metals react with water they form metal hydroxide and release hydrogen gas .
Metal + Water → Metal hydroxide + Hydrogen gas
Ex:- Zinc + water → Zinc hydroxide + Hydrogen gas
Metal + Water → Metal hydroxide + Hydrogen gas
Ex:- Zinc + water → Zinc hydroxide + Hydrogen gas
Zn + 2H2O → Zn(OH)2 + H2
2(A):- When Sodium reacts vigorously with cold water at room temperature, than they form
Sodium hydroxide and release Hydrogen gas.
Sodium + Water → Sodium hydroxide + Hydrogen gas
2Na + 2H2O → 2NaOH + H2
2(B):- When Calcium reacts vigorously with cold water at room temperature, than they form
Calcium hydroxide and release Hydrogen gas.
2(A):- When Sodium reacts vigorously with cold water at room temperature, than they form
Sodium hydroxide and release Hydrogen gas.
Sodium + Water → Sodium hydroxide + Hydrogen gas
2Na + 2H2O → 2NaOH + H2
2(B):- When Calcium reacts vigorously with cold water at room temperature, than they form
Calcium hydroxide and release Hydrogen gas.
Calcium + Water → Calcium hydroxide + Hydrogen gas
Ca + 2H2O ➞ Ca(OH)2 + H2
3- When metals react with dilute acid they form salt and release hydrogen gas .
Metal + Dilute Acids → Salt + Hydrogen gas
3(A):- When Zinc react with Dilute hydrochloric Acid than they form Zinc chloride which is a salt
and release Hydrogen gas
Zinc + Dilute hydrochloric acid → Zinc chloride (salt) + hydrogen gas
Zn + 2HCl → ZnCl2 + H2
3(B):- When Aluminum react with nitric acid then they produce Aluminum nitrate, Nitrogen oxide
and water.
Aluminum + Nitric acid → Aluminum nitrate + Nitrogen oxide + water
Al + HNO3 → Al(NO3)3 + NO2 + H2O
Aluminum react with nitric acid to produce aluminum nitrate, nitrogen dioxide and water.
Aluminum react with nitric acid to produce aluminum nitrate, nitrogen dioxide and water.
Aluminum react with nitric acid to produce aluminum nitrate, nitrogen dioxide and water.
Al + 6HNO3 → Al(NO3)3 + 3NO2 + 3H2O
Source
Source
Metal Oxide + Water → Metal Hydroxide (Base)
4(A):- When sodium oxide reacts with water then they formed Sodium hydroxide
Sodium oxide + Water →Sodium Hydroxide
Na2O + H2O → 2NaOH
4(B):- When Magnesium oxide reacts with water then they formed Magnesium hydroxide
Magnesium oxide + Water →Magnesium Hydroxide
MgO + H2O → Mg(OH)2
4(C):- When Potassium oxide reacts with water then they formed Potassium hydroxide
Potassium oxide + Water →Potassium Hydroxide
K2O + H2O → 2KOH
Hydrogen gas.
Zinc + Sodium hydroxide → Sodium zincate + Hydrogen gas
Zn + 2NaOH → Na2ZnO2 + H2
5(B):-When Aluminium react with Sodium hydroxide then they formed Sodium aluminate
and release Hydrogen gas.
Aluminium + Sodium hydroxide + Water → Sodium aluminate + Hydrogen gas
2Al + 2NaOH + 2 H2O → 2 NaAlO2 + 2 H2
What is a displacement reaction?
Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound. Both metals and non-metals take part in displacement reactions.Certain metals have the capacity to displace some metals from the aqueous solutions of their salts.
A metal placed higher in the activity series can displace the metal that occupies a lower position from the aqueous solution of its salt.
The displacement reaction is not limited to metals only. Even non-metals can take part in these reactions.
Example : Reaction of iron nails with copper sulphate solution.
Take Copper sulphate sollution in a test tube.
Copper Sulphate is an aquas salt sollution which is blue in colour.
Now dipped an Iron nail in Copper sulphate sollution.
Iron displaced the copper from Copper sulphate and form iron sulphate because highly reactive metals replace the low reactive metals.
Ans:- Those elements that have properties of both metals and non-metals are called metalloids.
Ex:-
| ATOMIC NUMBER | SYMBOL | ELEMENT |
| 5 | B | Boron |
| 14 | Si | Silicon |
| 32 | Ge | Germanium |
| 33 | As | Arsenic |
| 51 | Sb | Antimony |
| 52 | Te | Tellurium |
| 84 | Po | Polonium |
What are minerals?
Ans:- Those naturally occurring homogeneous solid which have a definite chemical composition and a highly ordere atomic arrangement. those are found mostly in combined state with many impurities are called minerals.
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