Form 4

Question 1

Who proposed that matter is composed of particles called atoms?

Answer 1

John Dalton

Dalton’s atomic theory laid the foundation for modern chemistry.

Question 2

What is the definition of an atom according to Dalton?

Answer 2

A spherical body that is small, indivisible, and cannot be created or destroyed

Atoms of the same element are identical in mass and properties.

Question 3

What model did John Dalton propose?

Answer 3

Dalton’s Atomic Model

This model describes atoms as indivisible spheres.

Question 4

Who discovered the negatively charged particle called the electron?

Answer 4

J.J. Thomson

Thomson’s work led to the discovery of the electron in 1897.

Question 5

What was Thomson’s model of the atom?

Answer 5

A sphere with positive charge containing electrons

This model is often referred to as the ‘plum pudding model’.

Question 6

What did Ernest Rutherford discover about the atom?

Answer 6

The nucleus as the center of the atom

Rutherford’s gold foil experiment led to the discovery of the atomic nucleus.

Question 7

What are protons and where are they located?

Answer 7

Positively charged particles located in the nucleus

Protons contribute significantly to the mass of the atom.

Question 8

What is the significance of the nucleus in Rutherford’s model?

Answer 8

Almost all the mass of the atom is concentrated in the nucleus

The nucleus contains protons and neutrons.

Question 9

According to Rutherford, where do electrons move in the atom?

Answer 9

Outside the nucleus

This model led to the understanding of electron orbits.

Question 10

Fill in the blank: In Dalton’s theory, atoms of the same element have _______.

Answer 10

the same type of atom

This means that the properties of elements are consistent.

Question 11

True or False: Dalton’s model of the atom included the concept of a nucleus.

Answer 11

False

The concept of the nucleus was introduced later by Rutherford.

Question 12

Who proposed the model of the atom where electrons move in shells around the nucleus?

Answer 12

Niels Bohr

Niels Bohr’s model highlights the arrangement of electrons in defined orbits or shells.

Question 13

What are the components of the nucleus in Bohr’s model?

Answer 13

Protons

The nucleus is the central part of the atom, containing protons and neutrons.

Question 14

In Bohr’s atomic model, what surrounds the nucleus?

Answer 14

Electrons

Electrons orbit the nucleus in specific energy levels or shells.

Question 15

Who discovered the neutron?

Answer 15

James Chadwick

James Chadwick’s discovery of the neutron contributed significantly to atomic theory.

Question 16

What is the charge of a neutron?

Answer 16

Neutral

Neutrons have no electric charge, differentiating them from protons and electrons.

Question 17

What fraction of an atom’s mass is contributed by neutrons?

Answer 17

Almost half

Neutrons, along with protons, account for the majority of an atom’s mass.

Question 18

Fill in the blank: The nucleus contains protons and _______.

Answer 18

neutrons

Neutrons are essential for the stability of the nucleus.

Question 19

True or False: According to Bohr’s model, electrons are found in random orbits around the nucleus.

Answer 19

False

Bohr’s model specifies that electrons occupy fixed shells or energy levels.

Question 20

What does the term ‘petala’ refer to in the context of Bohr’s model?

Answer 20

Shells

‘Petala’ is the term used to denote the orbits or energy levels where electrons reside.