Page 97 - ICSE Chemistry 8

Review Your Learning

A. Answer in one word/a few words.
1. The scien st who proposed the plum pudding model ______________________
2. The scien st who conducted the famous gold foil experiment ______________________
3. Posi vely charged central part of the atom ______________________
4. The number of protons present inside the nucleus of an atom ______________________
5. Atoms of the same element having same atomic number but
diff erent mass number ______________________
6. The arrangement of electrons in diff erent shells around the nucleus ______________________

B. State whether the given statements are true (T) or false (F).
1. Atoms can neither be created nor destroyed.
2. John Dalton proposed that an atom is solid, indestruc ble and indivisible sphere.
3. The cathode rays consist of the posi vely charged par cles called protons.
4. Neutron was discovered in 1932 by James Chadwick.
5. Pro um, deuterium and tri um are isotopes of nitrogen.
6. When an atom donates electrons to acquire a stable electronic confi gura on, it becomes a posi vely
charged ion.

C. Explain the following models of an atom.
1. Thomson’s model of an atom 2. Rutherford’s model of an atom

D. Write the characteris cs of the following.
1. Cathode rays 2. Electrons 3. Anode rays
4. Protons 5. Neutrons 6. Isotopes
E. Answer the following ques ons.
1. Write a note on discovery of electron and proton.
2. How was the nucleus discovered?
3. Discuss the modern concept of an atom.
4. How is atomic number diff erent from mass number? Write the atomic numbers and mass numbers
of helium, boron, nitrogen, neon, silicon, chlorine and argon.
5. What is rela ve atomic mass?
6. Write the electronic confi gura on of beryllium, oxygen, neon, magnesium, silicon, sulphur, chlorine,
potassium and calcium.
7. What is valency? Diff eren ate between monovalent, divalent and trivalent elements.
8. How are electroposi ve and electronega ve ions formed?
9. Discuss how is a chemical bond formed. Diff eren ate between electrovalent bond and covalent
bond. Also state why an electrovalent bond also called ionic bond.

PROJECT
Create a PowerPoint presenta on on the topic ‘Atomic Structure’. Find the related informa on and images
using the Internet. Add audio and visual eff ects to your presenta on. Format it as per your choice.

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