Atomic Theory and Structure

Question 1

Smallest Unit of Ordinary matter
which dictates the properties of element

Answer 1

Atoms

Question 2

greek work atoms

Answer 2

“atomos” - Indivisible

Question 3

expressed the belief that all matter consists of very small, indivisible particles.

Answer 3

Democritus

Question 4

Three fundamental particles of an atom

Answer 4

Electron
Proton
Neutron

Question 5

stream of negatively charged particles

Answer 5

Electrons

Question 6

positively charged particles

defines the element

Answer 6

Protons

Question 7

Uncharged dense particle

Answer 7

Neutrons

Question 8

contains protons and neutrons. Mass of the atom

Answer 8

Nucleus

Question 9

correspond to the number of protons in the nucleus of an element

Answer 9

Atomic Number

Question 10

Formulated a precise definition of the indivisible building blocks of matter that we call atoms.

atom as the basic unit of an element that can enter into chemical combination.

Answer 10

John Dalton

Question 11

Postulates of Daltons Atomic Theory

Answer 11

All matter consists of atoms.

Atoms of one element cannot be converted into atoms of another element.

Atoms of an element are identical in mass and other properties and are different from atoms of any other element.

Compounds result from the chemical combination of a specific ratio of atoms of different elements.

Question 12

What was J.J. Thomson’s most significant discovery?

Answer 12

Electrons (1886)

Question 13

Oil-drop experiment

These experiments allowed him to determine the magnitude of the electron charge.

Answer 13

Robert Milikan

Question 14

How did Thomson discover the electron?

Answer 14

Through experiments with a cathode ray tube, observing that the beam of particles was deflected by electric and magnetic fields.

Question 15

A model where the atom is a sphere of positive charge with negatively charged electrons embedded within it.

Answer 15

Plum pudding model

Question 16

How did Thomson’s work contribute to the understanding of atomic structure?

Answer 16

It showed that atoms are divisible and contain smaller subatomic particles, leading to the development of more accurate atomic models

Question 17

What experiment did Rutherford use to discover the nucleu

Answer 17

Rutherford directed alpha particles at a thin sheet of metal foil, observing deflections to discover the nucleus.

Question 18

What did Rutherford conclude from the large deflections of alpha particles?

Answer 18

The large deflections indicated a concentrated positive charge in the atom’s center, which he identified as the nucleus.

Question 19

What did Rutherford expect to happen with the alpha particles in his experiment?

Answer 19

He expected them to pass through the foil with minimal deflections.

Question 20

atoms of an element with the same number of protons, but a different number of neutrons

Answer 20

Isotope

Question 21

contains charge. Either positive or negative charge.

Answer 21

Ion

Question 22

a type of ion that contains positive charge. It tends to lose electron. The magnitude of the charge is the number of electron that can be lost by an ion.

polyatomic

Answer 22

Cation

Question 23

a type of ion that contains negative charge. It tends to gain electron. The magnitude of the negative charge is the number of electron that can be gained by an ion

monoatomic

Answer 23

Anion

Question 24

Strictly defined as a combination of two or more atoms

Answer 24

Molecules

Question 25

Compound vs Molecule

Answer 25

All compound are molecule but not all molecule are compounds