Matter

Question 1

atom

Answer 1

an atom is the smallest particle of an element which can take part in a chemical reaction

Question 2

molecule

Answer 2

the smallest particle of an element or a compound which can exist freely in nature is called a molecule.

Question 3

structure of an atom

Answer 3

an atom is made up of three fundamnetal particles or sub- atomic particles. they are proton, neutron and electron.

Question 4

define proton, neutron and electron

Answer 4

protons are positively charged sub-atomic particles located in the nucleus of an atom.
neutrons are chargeless sub-atomic particles lcated in the nucleus of an atom.
electrons are the negatively charged sub-atomic particles that revolve around the nucleus in elliptical orbits or shell.

Question 5

why is atom electrically neutral?

Answer 5

an atom is eletrically neutral due to the presence of equal nubember is protons and electrons having opposite charges also due to this the overall charge of an atom is zero.

Question 6

atomic number

Answer 6

an atomic number of an atom is the total numbers of protons present in the nucleus of an atom.

Question 7

atomic mass

Answer 7

the sum of an atom is the total number of protons and neutrons present in the nucleus of an atom is called atomic mass or atomic weight.

Question 8

electronic configuration

Answer 8

electronic configuration is the systematic distribution of electrons in various orbits or energy levels around the nucleus of an atom.

Question 9

names of first 20 elements with atomic mass, valency, symbol and atomic number

Answer 9

hydrogen(H): atomic number 1, atomic mass 1, valency 1
helium (He): atomic number 2, atomic mass 4, valency 0
lethium (Li): atomic number 3, atomic mass 7, valency 1
beryllium (Be): atomic number4,atomic mass 9,valency 2
boron (B): atomic number 5,atomic mass 11, valency 3
carbon (C): atomic number 6,atomic mass 12, valency 4
nitrogen (N): atomic number7, atomic mass 14, valency 3
oxygen (O): atomic number 8, atomic mass 16, valency 2
fluorine F): atomic number 9, atomic mass 19, valency 1
neon (Ne): atomic number 10, atomic mass 20,valency 0
sodium (Na): atomic number 11,atomic mass23,valency 1
magnesium (Mg): atomic number 12, atomic mass 24, valency 2
aluminium (Al): atomic number 13, atomic mass 27, valency 3
silicon (Si): atomic number 14, atomic mass 28,valency 4
prosphorus (P): atomic number 15, atomic mass 31, valency 3
sulphur (S): atomic number 16,atomic mass 35,valency 2
cholrine (Cl): atomic number 17, atomic mass35,valency 1
argon (Ar): atomic number 18, atomic mass 40,valency 0
potassium (K): atomic number 19, atomic mass 39, valency 1
calcium (Ca):atomic number 20, atomic mass 40, valency 2

Question 10

symbol

Answer 10

the abbreviation of the full name of an element is called symbol.

Question 11

valency

Answer 11

valency is the comining capacity of an atom or a radical with another atom or radical to form a a molecule.

Question 12

radicles

Answer 12

radicals are charged atoms or group of atoms having a common charge which acts as a single unit during a chemical reaction.

Question 13

exceptions while writing valency and amu

Answer 13

elements which have odd atomic no. have n= p+1
elements which have odd atoic no. have n= p
exception: 1,4,7&18
2×atomic number= atomic weight(even numbers)
2× atomic nuber +1= atomic weight (odd nubembers)
exception= 1,4,7,&18

Question 14

molecular formula

Answer 14

a molecular formula is defined as the symbolic representation of the molecule of an element or a compind in a molecular form.

Question 15

molecular weight

Answer 15

the molecuale weight of a molecule is defined as sum of atomic weights of the atoms preent in the molecule.

Question 16

periodic table

Answer 16

the table in which these elements are arranged inro periods and groups on the basis of their properties is called a periodic table.

Question 17

mandeleev’s periodic table

Answer 17

mandeleev’s periodic law states that, “ the physical and chemical properties of elements are a periodic function of their atomic weight.”

Question 18

mordern periodic table

Answer 18

the mordern periodic law states that, “the physical and chemical properties of elements are a periodic function of their atomic numbers.”

Question 19

chemical reaction

Answer 19

the combination , decomposition or displacement that occurs in molecules of matter during a chemical chanfe is called a chemical reaction.

Question 20

word equation

Answer 20

a word equation is the chemical reacion expressed by writing the full names of reactants and products.

Question 21

balanced chemical equation

Answer 21

the chemical equation written by balancing the total number od atoms of each element in reactanta and products is caled a balanced chemical equation.

Question 22

unbalanced chemical equation

Answer 22

the chemical equation in which the total number od atoms of each element in reactants and products are not equal is called unbalanced chemical equation.