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FORMATIVE ASSESSMENT IN CHEMSTRY FOR CLASS IXTopic: Structure of atomContent Analysis:

- Charged particles in matter- Structure of an atom:

o Thomsons Modelo Rutherfords Modelo Bohrs Modelo Neutrons

- Distribution of electrons in different orbits.- Valency- Atomic number and mass number- Isotopes and isobars

Learning OutcomesAfter this chapter, learners will be able to

- describeo Thomsons Modelo Ruther fords Modelo Bohrs Model

- Describe how electrons are filled in different orbits.- Define valency and assign valency to different elements.- Differentiate and define isotopes and isobars.- List the drawbacks of Rutherfords or Thomsons model.

FORMATIVE ASSESSMENT IN CHEMSTRY FOR CLASS IXFor designing and developing tools for formative assessment in

chemistry, we take, as an example, unit 4 (Structure of Atoms) of class IX.

I) For assessing knowledge: This question has been framed using the conceptof atomic numbers.

a) An element has atomic number 27. The number of protons present inan atom of this element is:

i. 27ii. 30

iii. 32iv. 25


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Ans : (i)

Assessment method: This is a one mark question. There is only one correct

answer and the child will get one mark for ticking the correct answer.

b) The atom of an element has 3 electrons in the M-Shell. What is its atomic

number?

a) 13 b) 3 c) 5 d) 20

Ans:- (a)

Assessment: This is one mark question. There is only one correct answer and the child

will get one mark for ticking the correct answer.

II) For assessing knowledge and understanding.a) An element X, having atomic number 16, gains two electrons to form

and anion X. What will be the atomic number of X in the anion?

i. 14ii. 16

iii. 18iv. None of the above

Ans:- (ii)

Assessment method: This is a one mark question. There is only one correctanswer and the child will get one mark for ticking the correct answer. If he

ticks the wrong answer, he can be explained the source of the mistake. The

child has to be given the concept that atomic number is the number of protons

present in atom and protons are not involved in the formation of ions.

b). Fill Ups using these clues:

Electrons, Protons, Neutrons, Octet, Mass Number, Atomic Number

a)________are present in nucleus of all atoms ,except Hydrogen.( 1H1).

b)The Mass of an _________is considered to be negligible and its charge is

minus one.


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c)If there are 11 electrons and 12 protons ,then the ____________of a

particular neutral atom is 23.

d)In a neutral atom, no. of protons ,no. of electrons and __________are equal.

e)In charged particles ,atomic number is equal to 15 then its number

of_________are

also 15.

f)An outermost shell which had eight electrons was said to possess an

_________.

Ans: - a) Neutrons b) Electrons c) Mass Number d)Atomic No.

e)Protons f) Octet

Assessment: This is three mark questions. There is only one correct answer and the

child will get half mark for filling in the correct answer in the fill up.

III) For assessing applicationa) An element is represented as X. The number of neutrons in an

atom of X is equal to__________.

Assessment method: This question has been framed using the concept of

atomic number and mass number. This is a one word answer question. If

the child writes the correct answer in the blank, he will get one mark.

Ans: - 143

IV) For assessing interpretation of dataa) Given below are Bohrs models for elements whose atomic numbers are

given.

X (At. No. = 17) Y (At. No. = 18) Z (At. No. = 19)


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Which of these models represent a neutral atom, which one represents a

Cation and which one is an anion?

Ans:- Y-Neutral Atom Z-Cation X-Anion

Assessment method: This question is a three mark question, but no

explanation is required to be given one mark will be given answering each

part.

b) Activity: Draw atomic structures based on the information provided for

some species, mentioned below:

a) Z=9

b) A=20, n=10 (when e=p)c) P=13 (no. of electrons are 3 less than number of protons)

d) Z=16 and number of electrons are 2 more than number of protons.

Ans) a

Ans) b

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Ans) c

Ans) d

Assessment: Children will be able to correlate between atomic number, Mass Number

Electrons and Protons. They will be able to draw atomic structures for cations, anions

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and neutral atoms. 1 Mark each will be given for calculating the right number of

electrons and 1 mark for drawing atomic structure correctly.

V) For assessing understanding and application

Atomic numbers of some elements are given below. Assign valency to each of

these elements.

A. (At no. =16), B. (At no. = 12)

C. (At no. = 5), D. (At no. = 10)

Ans) A=2 B=2 C-3 D=0Assessment method: This is 4 marks question one mark for each part. No

explanation is required.

Drawing Skill

Write the distribution of electrons in phosphorous and aluminium atom.

Draw the Bohrs model of the above two.

Ans) Phosphorus = K L M2 8 5

Aluminium 2 8 3

Phosphorous Aluminium

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Assessment: This is three marks question. There is half mark for writing the

electronic distribution of both elements and one mark each for drawing the correct

model for both atoms.

Remedial Measures

1. Recapitulation of placement of Electrons, Protons, Neutrons in Structure ofAtom.

2. Concept of Atomic Number and Atomic Mass to be emphasized.3. Relation in between Atomic Number of Atom and Anion.

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