2a the structure of the atom-answer

8/8/2019 2A the Structure of the Atom-Answer

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WAJA F4 Chemistry Chapter 2 : The Structure of Atom

CHAPTER 2 : THE STRUCTURE OF ATOM (ANSWER)

Activity 1(refer text book pg 11, 12,)

1. tiny, discrete2. molecules, ions3. smallest, take part4. atoms, chemically5. positively-charged6. in7. gas, liquid, solid, movement, different arrangement8. absorbed, released

Activity 2(refer text book pg 13,14,15)1.

State of matter Solid Liquid Gas

Draw the particles

arrangement

Particlesarrangement

The particles arepacked closelytogether in an orderlymanner

The particles are lessclosely packed but notin orderlyarrangement

The particles are furtherapart from each other.

Particles movementParticles can onlyvibrate and rotateabout their fixpositions.

Particles are attractedby very strong forces.

Particles are attracted bymoderately strongforces.

Attractive forces

between theparticles

Particles are

attracted by a verystrong forcesbetween the partcles

Particles are held

together by strongforces but weakerthan the forces insolid /(moderately)

The attraction forces

between particles areweak forces

Energy content ofparticles

Very low energy Moderately highenergy.

Very high energy

2. When heat energy is supplied to particles in matter, its kinetic energy (increase/decrease) andthe particles in matter vibrate ( faster/ slower) When matter loses heat energy, the kineticenergy of the particles (increase/decrease) and they vibrate ( faster/ slower).

3. A : Melting B : Boiling/ Evaporating C : Freezing

D : Condensation E : Sublimation F : Sublimation

4. (a) solid, melting point, liquid, gas, absorbed, overcome, intermolecular

5.Point States of matter Explanation

A to B Solid Heating causes the particles to absorb more energyand vibrate faster. The temperature of the substance

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and the kinetic energy increases.

B to C Solid and liquid Continuous heating does not cause the temperatureof the substance to increase. The energy absorbed isused to overcome the forces of attraction betweenthe particles. The constant temperature is called the

melting point.

C to D Liquid Continuous heating causes the temperature of theliquid to increase. The particles move faster becausetheir kinetic energy increase.

6. (a)Point State of matter Explanation

P to Q Liquid As cooling continues, particles lose more kineticenergy, move slower and the temperaturedecreases.

Q to R Liquid and solid The stronger bonds formed during freezingrelease energy. This energy released is the sameas the energy lost to the surroundings duringcooling. Thus the temperature remainsunchanged. This constant temperature is calledfreezing point

R to S Solid The solid is cooled. The particles vibrate slower asthe temperature decreases

(b) liquid, solid, exactly balanced,

Activity 3(refer text book pg 16, 17,)

Model Structure(Refer text book pg 16,17)

Characteristic

Daltons atomic model(proposed by JohnDalton in 1805 )

The atom was imagined as a smallindivisible ball similar to a very tiny ball.

Thomsons atomicmodel(proposed by J.JThomson in 1897 )

J.J Thomson discovered the electrons, anegatively-charged particle.The atom was describe as a sphere ofpositive charge embedded with electrons.

Rutherfords atomicmodel(proposed by Ernest

Ernest Rutherford discovered proton, apositively-charged particle in an atom.The central region of atom has a very smallpositively-charged particles, which contains

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Rutherford in 1911 ) almost all the mass of the atom.

Bohrs atomic model(proposed by NeilsBohr in 1913 )

The electrons in an atom move in shellsaround the nucleus which contains protons.

Chadwicks atomicmodel (proposed byJames Chadwickin 1932 .)

Chadwick proved the existence of neutrons,the neutral particle in the nucleus.The nucleus of the atom contains protons &neutrons, and the nucleus is surrounded byelectrons.

Activity 4

1. neutrons, electrons

2. protons, neutrons, electrons

Subatomic particle Symbol Relative mass Relative electriccharge

Proton p 1 +1

Neutron n 1 0

Electron e 1/1840 -1

3. protons

4. protons, neutrons

5. The nucleon number is also known as the mass number.

NUMBER OF NEUTRON = NUCLEON NUMBER -- PROTON NUMBER

= A - Z

Symbols Of Elements

The standard representation for an atom of any element shows the proton number and thenucleon number of the element. It can be written as follows:

A XZ# A Nucleon number

Z proton numberX symbol of element

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1H1

21Sc45

Proton numberNucleon number

2He4

3Li

7

4Be

9

5B

11

6C

12

7N

14

8O

16

9F

19

10Ne

20

11Na23

12Mg24

13Al27

14Si28

15P31

16S32

17Cl35

18Ar40

19K39

20Ca40

21Sc45

6. Consider part of the periodic table of the element above and complete the table below.

Element Symbol Protonnumber

No. ofelectron

Nucleonnumber

No. ofneutron

Standardrepresentation

Scandium Sc 21 21 45 24

Aluminium Al 13 13 27 14

Argon Ar 18 18 40 22

Beryllium Be 4 4 9 5

Boron B 5 5 11 6

Calcium Ca 20 20 40 20

Carbon C 6 6 12 6

Chlorine Cl 17 17 35 18 Cl3517

Fluorine F 9 9 19 10

Helium He 2 2 4 2

Hydrogen H 1 1 1 0

Lithium Li 3 3 7 4

Magnesium Mg 12 12 24 12

Neon Ne 10 10 20 10

Nitrogen N 7 7 14 7

Oxygen O 6 6 16 10 O168

Phosphorus P 15 15 31 16

Potassium K 19 19 39 20

Activity 5( refer text book pg 20)

1. same number, different number

2.

Element Number of isotopes

Symbol ofisotopes

Number ofprotons

Number ofelectrons

Number ofneutrons

Name ofisotopes

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3. the outermost occupied

4.

Atom of Elements Electron Arrangement Number of valance electron

Oxygen 2.6 6

Aluminium 2.8.3 3

Chlorine 2.8.7 7

Neon 2.8 8Potassium 2.8.8.1 1

Magnesium 2.8.2 2carbon 2.4 4

phosphorus 2.8.5 5helium 2 2

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2a the structure of the atom-answer

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