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TOPIC 5 : ATOMIC STRUCTURE QUESTIONS WITH ANSWERS ~ CHEMISTRY FORM TWO 2

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TOPIC 5 : ATOMIC STRUCTURE QUESTIONS WITH ANSWERS ~ CHEMISTRY FORM TWO 2

QUESTIONS AND ANSWERS

    QUESTIONS:

  1. choose the most correct answer from thealternatives given.

  (i) It is a part of an atom that provides its  mass

      A: shell   B: nucleus    C: neutron

      D: electron

  (ii) Electrons that found closer to the nucleus are  ________ than found far from the nucleus.

       A: heavier   B: lighter   C: stronger

       D: weaker

  (iii) If an atom has 14 electrons and 14 protons it is said to be

        A: neutral atom  B: charged atom  C: di atom  D: isotope

 (iv) Which of the following is NOT apart of Dalton’s atomic theory?

A: All elements are composed of atom

B: Atoms are always in motion.

C: Atoms of the same element are identical.

D: Atoms of different elements may combine to form compounds.

(v) All atoms are neutral because

A: They are contained with nucleus and shells.

B: They have both electrons and protons.

C: Electrons and protons contained equally in them.

D: They have equal number of protons and neutrons.

TOPIC 5 : ATOMIC STRUCTURE QUESTIONS WITH ANSWERS ~ CHEMISTRY FORM TWO 2

(vi) According to Rutherford, which statement is true about the model of an atom?

A: The nucleus is made up of electrons and protons

B: Electrons are distributed around the nucleus.

C: Sub-atomic particles are distributed throughout the atom.

D: Neutrons found in shells of an atom.

(vii) If an atom is neutral and it has 24 electrons. What is its atomic number?

 A: 48    B: 12     C: 24     D: 6

(viii) Which particle of an atom represent the atomic number of an atom?

A: The total number of electrons.

B: The total number of neutrons

C: The total number of protons.

D: Mass number

(ix) One of the following is a characteristic of nucleus of an atom.

A: It is central part with low density.

B: It is neutral(not charged).

C: it contains only protons

D: it is central part with relative high density

(x) Subtracting number of neutrons from the mass number we get_____

A: Atomic weight  B: number of electrons   C: number of protons  D: Density

TOPIC 5 : ATOMIC STRUCTURE QUESTIONS WITH ANSWERS ~ CHEMISTRY FORM TWO 2

  1. Match items in list A

  with responses in list  B

  List  A

(i) A negatively charged particle of an atom.

(ii) Protons and neutrons

(iii) Shell K

(iv)Electronic configulation of carbon atom.

(v) The part in atom where there is great probability of finding electrons.

(vi) Nuclide notation

(vii) Isotopes

(viii) Relative atomic number

(ix) Neutrons

  List  B.

A: Have equal atomic number but different number of neutrons.

B: Shows sub atomic particles which present in an atom.

C: Nucleons

D: Isotopy

E: Forms mass number with protons

F: Found in both shells and nucleus.

G: Have equal number of neutrons but different mass number.

H: Average mass of isotopes.

I: Carries maximum of 8 electrons

J: Carries maximum of 2 electrons

K: Electron

L: Shell

M: 2:4

N: 2:8:2

  1. Write T for the correct statement and F for incorrect statement.

(i) The mass of an atom is equal to the mass of its nucleus.

(ii) Isotopy are atoms of the same element having the same atomic number but different mass number.

(iii) If an atom has 3 shell, it has ability of carrying maximum of 24 electrons.

(iv) If an atom has 3 shell, it has ability of carrying minimum of  11 electrons.

(v) Sub atomic particles that found in the nucleus of an atom are not negatively charged.

  1. State Dalton’s atomic theory and its modification.
  2. It is said that, the mass of an atom is contributed only by nucleons and not electrons. Explain why?
  1. Explain(define) the following.

   (a) Atom

   (b) Electron

   (c) neutron

   (d) proton

   (e) atomic number

   (f) mass number

   (g) nucleon

   (h) isotopes

   (i) isotopy

   (j) nuclide notation

TOPIC 5 : ATOMIC STRUCTURE QUESTIONS WITH ANSWERS ~ CHEMISTRY FORM TWO 2

  1. State three characteristics of each sub atomic particle.
  1. (a) Differentiate

    (i)electron from nucleons.

    (ii) electron from proton

    (iii) proton from neutron.

 (b) Show the similarities between proton and neutron.

  1. Write the electronic configuration for the elements with the following electrons.

 (a) 6   (b) 1   (c) 13   (d) 20

  1. P, M, N and G are isotopes if element Q, their abundances are 2%(204 mass number) 24%(206 mass number), 22%(207 mass number) and G%(A mass number) respectively. The relative atomic mass of element Q is 207.

Calculate (i) abundance G and

                 (ii) mass A

  1. Atom J has mass number 49 and atomic number 24 calculate its neutron number.
  1. Neon has three isotopes. Neon with mass 20(90.5%), 21(0.3%) and 22(9.2%)

 Calculate its R.A.M

TOPIC 4 : ATOMIC STRUCTURE QUESTIONS WITH ANSWERS ~ CHEMISTRY FORM TWO 2

     ANSWERS:

  1. (i) B(ii) B    (iii)  A   (iv) B    (v) C   (vi) B   (vii) C     (viii) C    (ix) D     (x) C
  1. (i) K(ii) C    (iii) J  (iv) M   (v) L.  (vi) B     (vii) A    (viii) H    (ix) E
  1. (i) T(ii) F    (iii) F    (iv) T     (T)
  1. Dalton’s Atomic theory

John Dalton developed his theory about the

atom with five main points as follows

  1. Matter is made up of tiny particles called

atom

  1. Atoms cannot be created or destroyed

iii. Atom of any one element are identical

and have the same chemical properties

and the same mass

iv.Atom of a given element are different

from those of any other element

  1. Atoms of one element can combine in

simple ratio with the atom of another

element to form a compound atoms or

molecules

Modification from Dalton’s Atomic theory

  1. Atom is made by sub atomic particle such

as electrons, protons and neutrons

  1. Atoms can be created or destroyed

iii. Atom of any one element can differ

example isotopes

iv.Atoms of one element can combine in

any ratio with the atom of another

element

  1. The mass of an atom is said to be contributed by neutrons and protons because the mass of electrons is very small such that it is neglected.

TOPIC 5 : ATOMIC STRUCTURE QUESTIONS WITH ANSWERS ~ CHEMISTRY FORM TWO 2

  1. (a) Atom:- is a smallest particle of an element which has all chemical properties of that element

    (b) Electron:- is a negatively charged particle of an atom.

    (c) Neutron :- is a sub-atomic particle of an atom which has no charge.

   (d) Proton :- is a positively charged particle particle of an atom.

   (e) Atomic number:-refers to the number of protons of an atom.

   (f) Mass number:- refers to the total number of protons and neutrons.

   (g) Nucleons:- Are sub-atomic particles which found in the nucleus of an atom.

   (h) Isotopes:- Are atoms of the same element which have the same atomic number but different mass number.

  (i) Isotopy:- Refers to existence of atoms of the same element having the same atomic number but different mass number.

  (j) Nuclide notation:- is the way of representing sub-atomic particles of an atom.

  1. Sub-atomic particles:- are substances which form structure of an atom.

 They include

     -electrons

     -protons

     -neutrons

Characteristics of electrons.

   -Are negatively charged

   -They found outside the nucleus

   -The relative mass of an electron is 1/1840

Characteristics of protons.

  -They are positively charged

  -They found in the nucleus of an atom.

  -The relative atomic mass of atom is 1

Characteristics of neutrons.

  -They are not charged

  -They found in the nucleus of an atom

  -The relative atomic mass of neutron is 1.

TOPIC 5 : ATOMIC STRUCTURE QUESTIONS WITH ANSWERS ~ CHEMISTRY FORM TWO 2

  1. (a) (i) Difference between electron and nucleons.

    -Electron found outside the nucleus of an atom While nucleons found in the nucleus of an atom.

   -Electron does not contribute the mass of an atom While nucleons form form the mass of an atom

  (ii) Difference between electron and proton.

     -Electron is positively charged While proton is positively charged.

     -Electron found outside the nucleus While proton found in the nucleus of an atom.

     -Electron has mass 1/1840 While proton has mass 1.

 (iii) Difference between proton and neutron.

       -Protons is positively charged While neutron has no charge.

       -Protons affect atom to be either charged or neutral While neutron does not affect the charge of an atom.

 (b) Similarities between proton and neutron.

    -both proton and neutron found in the nucleus.

    -both proton and neutron contribute the mass of an atom.

  1. When writing electronic configulation of an atom, electrons should first filled in first shell from the nucleus before the next shell and each shell must filled with correct number of electrons before the next shell.

  (a) 2:1

  (b) 1

  (c) 2:8:3

  (d) 2:8:8:2

  1. Solution.

      Given data:

   Atomic masses

            P=204

           M=206

           N =207

           G = A

  Abundances:

     P=2%

     M=24%

     N=22%

     G=A

R.A.M = 207

Abundance G=needed

Atomic mass A= needed

  (i) Abundance G

      Abundance G=100 – total abundance P, M and N

  =100 – 2 + 24 +22

  = 52

Abundance G = 52%

 (ii) mass A.

  From

     R.A.M=(mass x abundance) + (mass x abundance)/100

        207=(204 x 2) + (206 x 22) + (A x 52)/100

       207=(9906 + 52A)/100

     52A = 20700-9906

    52A = 17904

       A= 17904/52

 Mass A = 308

  1. Solution.

     Given data.

         Mass number(A) = 49

         Atomic number(Z)=24

        Number of neutron= needed

 From

     A=Z + n

   n= A – Z

 Where by A=mass number

                   Z=atomic number

                   n=neutron number

    n=49 – 24

      = 25

Neutron number of atom J is 25

12: Solution.

    Given data:

     Atomic masses= 20, 21 and 22

     Abundances= 90.5%, 0.3% and 9.2% respectively.

    R.A.M =Needed

    R.A.M =(mass x abundance) +(mass x abundance)/100

      =((20 x 90.5) + (21 x 0.3) + (22 x 9.2))

                                 100

      R.A.M =20.2

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