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When we rub two objects together they become electrically charged. Where did this electric charge come from?
How cathode rays are different from anode rays?
Name the discoveror of electrons, protons and neutrons.
What conclusion would be drawn by Rutherford when he observed that most of the fast moving α-particles passed straight through the gold foil?
Nucleus of an atom is positively charged and electrons around it are negatively charged. Then why do electrons not just fall to the nucleus out of attraction?
What do you understand by the term ‘discrete orbit’?
Draw a sketch of Bohr’s model of an atom with four shells.
What can be the maximum number of electrons in the outermost orbit?
Find out the number of electrons present in the last shell of an atom having atomic number 15.
In an atom first four shells (K, L, M, and N) are completely filled. Then what is the total number of electrons in that atom?
Why helium and neon do not take part in chemical reactions?
A non-metal has 6 electrons in its outermost shell. Predict its valency.
What are the number of protons, neutrons, and electrons in What are their atomic number and mass number?
The atomic number of Al and Cl are 13 and 17 respectively. What will be the number of electrons in Al3 + and Cl–?
Lithium atom has an atomic mass of 6u and three protons in its nucleus. How many neutrons does it have?
An atom has an atomic mass of 7u. It has 2 electrons in K-shell and one electron in L-shell. How many neutrons does it have?
Why are atomic masses of most of the elements are fractional and not whole numbers?
Identify the isotopic pair(s) out of the following species?
8C16, 6C14, 7N14, 8O18, 7N16
(i) Name the isotope used as a fuel in nuclear reactors.
(ii) What is the number of sub-atomic particles in this isotope?
Why are anode rays called so?
Mention the charge present on the nucleus of an atom.
How can an α-particle be represented?
Does the nucleus contain neutrons also?
An element X has 5 electrons in its M-shell. What is its atomic number?
give the number of neutrons in an atom of element .
An element has mass number = 35 and atomic number = 17 find
(i) The number of neutrons in the element,
(ii) The number of electrons in the outermost shell.
If an atom of an element has atomic number = 15 and, mass number = 31, find the number of protons, electrons, neutrons in its atoms.
Why do isotopes of an element have different physical properties?
How are the following pairs of atoms related?
8X16, 8X17, 18Y40, 20Z40,
Why is electron known as a universal particle?
How an element is represented using its mass number and atomic number. Give some examples.
List two difference between electron, proton, and neutron.
Express the combining capacity (valency) of .
Which of the two elements would be more reactive, element A of atomic number = 36 or element B of atomic number = 19?
An element has Z = 11, what is the valency of the element? Also, name the element.
In , determine the number of
(i) neutrons
(ii) number of protons
An ion M2– contains 10 electrons and 10 neutrons. What are the atomic number and mass number of the element M? Name the element.
A naturally occurring sample of lithium contains 7.42% of 6Li and 92.58% of 7Li. The relative atomic mass of 6Li is 6.015 and that of 7Li is 7.016. Calculate the atomic mass of a naturally occurring sample of lithium.
Describe the essential properties of the atomic nucleus. Compare these with the properties of the electron.
The electronic configurations of some elements are given below. Name the elements.
(i) 2, 8, 5
(ii) 2, 8, 8, 2
(iii) 2, 8, 1
An atom X has 4 protons and 5 neutrons with electronic configuration 2, 2.
Give information about its
(i) atomic number
(ii) mass number
(iii) valency
The number of neutrons and protons present in the nuclei of two atomic species A and B are given below.
(i) Write the mass numbers of A and B.
(ii) What is the relation between two species?
(iii) Write the electronic configuration of atoms A and B.
What information do you get from the figure given below about the atomic number, mass number and valency of atom X?
A certain species X has 17 protons, 18 electrons and 20 neutrons.
(i) What is such a particle called?
(ii) What is the mass number of X?
(iii) What is the atomic number of X?
If K and L-shells of an atom are full and in M-shell, there is only one electron, then what would be the total number of electrons in the atom? Name the element. Write the symbol and draw the Bohr model.
An atom of an element has 17 proton, 17 electrons, and 18 neutrons.
(i) Calculate the mass number of the element.
(ii) Write its electronic configuration.
(iii) Find the valency and an atomic number of the element.
An element X has a mass number = 37 and it contains 17 protons.
(i) Write the symbolic representation of the element.
(ii) Find the number of neutrons and electrons in the element.
(iii) Write the electronic configuration of the element.
The atomic number and the mass number of certain elements are given below in the table.
(i) Select a pair of isobar and isotope from the above table.
(ii) What would be the valency of elements B and E?
What are the features and drawbacks of Rutherford’s nuclear model of an atom?
How did the discovery of protons take place?
Why do helium, neon, and argon have zero valencies?
(i) What are inert elements? Why are they called so?
(ii) What is the valency of these elements and why?
(iii) How many electrons can be accommodated in a M and N-shell?
(i) Draw the atomic structures of the following elements: Magnesium, silicon, sulphur.
(ii) What is the atomic number and mass number of the element whose atomic structure is shown in below?
Areeba’s younger brother is suffering from dehydration. To combat dehydration she suggested him to take non-alcoholic drink like coconut water, barley water, sugarcane juice, glucose water etc., in plenty. Every cell in out body needs water in order to function properly as out body contains about 70% of water.
Read the above passage and answer the questions that follows:
(i) Name the elements present in water.
(ii) Write electronic configuration of both the elements.
(iii) How will you make children aware of taking sufficient amount to liquids and water to prevent dehydration?
A picnic was planned for Class IX students to an amusement park. A chemistry teacher who accompanied the students instructed them to go for a ride as follows: Only two students could go for a first ride. Second ride could accommodate eight students. Third ride could accommodate remaining seven students.
(i) The above situation can be compared with the structure of an element. name that element.
(ii) Is this element metal or non-metal? What is its valency?
(iii) What are the values associated with the students?
In the Thomson’s model of the atom, which of the following statements are correct?
(i) The mass of the atom is assumed to be uniformly distributed over the atom.
(ii) The positive charge is assumed to be uniformly distributed over the atom.
(iii) The electrons are uniformly distributed in the positively charged sphere.
(iv) The electrons attract each other to stabilize the atom.
Options || A. (i), (ii) and (iii)
B. (i) and (iii)
C. (i) and (iv)
D. (i), (iii) and (iv)
Which of the following statements about Rutherford’s model of an atom are correct?
(i) Considered the nucleus are positively charged.
(ii) Established that the α-particles are four times as heavy as a hydrogen atom.
(iii) Can be compared to solar system.
(iv) Was in agreement with Thomson’s model.
Options || A. (i) and (iii)
B. (ii) and (iii)
D. Only (i)
The following diagram depicts Rutherford’s experiment.
Why was zinc sulphide screen in used in the experiment?
Options || A. To block α-particles from going straight.
B. To detect deflection of α-particles.
C. To further deflect α-particles as the gold foil did.
D. To absorb α-particles and utilise it again.
Atomic models have been improved over the years. Arrange the following atomic models in the order of their chronological order.
(i) Rutherford’s atomic model
(ii) Thomson’s atomic model
(iii) Bohr’s atomic model
Which of the following are true for an element?
(i) Atomic number = Number of protons + number of electrons
(ii) Mass number = Number of protons + number of neutrons
(iii) Atomic mass = Number of protons = Number of neutrons
(iv) Atomic number = Number of protons = Number of electrons
Options || A. (i) and (ii)
C. (ii) and (iii)
D. (ii) and (iv)
The number of electrons in an element X is 15 and the number of neutrons is 16. Which of the following is the correct representation of the element?
Options || A.
B.
C.
D.
Different isotopes are matched with their uses as
I. Co-60-To treat cancer
II. U-238-To produce electricity
III. I-131-To treat goitre
IV. Na-24-In agricultural research
C. (iii) and (iv)
D. (i) and (iii)
In a sample of ethyl ethanoate (CH3COOC2H5) the two oxygen atoms have the same number of electrons but different number of neutrons. Which of the following is the correct reason for it?
What are their atomic number and mass number?
.
.
, determine the number of
